Professor Satheesh Krishnamurthy FRSC, FIMMM

A study of ${B}_c^{+}\to J/\psi {D}_s^{+}$ and ${B}_c^{+}\to J/\psi {D}_s^{\ast +}$ decays using 139 fb–1 of integrated luminosity collected with the ATLAS detector from $\sqrt{s}$ = 13 TeV pp collisions at the LHC is presented. The ratios of the branching fractions of the two decays to the branching fraction of the ${B}_c^{+}$ → J/ψπ+ decay are measured: $\mathcal{B}\left({B}_c^{+}\to J/\psi {D}_s^{+}\right)/\mathcal{B}\left({B}_c^{+}\to J/{\psi \pi}^{+}\right)$ = 2.76 ± 0.47 and $\mathcal{B}\left({B}_c^{+}\to J/\psi {D}_s^{\ast +}\right)/\mathcal{B}\left({B}_c^{+}\to J/{\psi \pi}^{+}\right)$ = 5.33 ± 0.96. The ratio of the branching fractions of the two decays is found to be $\mathcal{B}\left({B}_c^{+}\to J/\psi {D}_s^{\ast +}\right)/\mathcal{B}\left({B}_c^{+}\to J/\psi {D}_s^{\ast +}\right)$ = 1.93 ± 0.26. For the ${B}_c^{+}\to J/\psi {D}_s^{\ast +}$ decay, the transverse polarization fraction, Γ±±/Γ, is measured to be 0.70 ± 0.11. The reported uncertainties include both the statistical and systematic components added in quadrature. The precision of the measurements exceeds that in all previous studies of these decays. These results supersede those obtained in the earlier ATLAS study of the same decays with $\sqrt{s}$ = 7 and 8 TeV pp collision data. A comparison with available theoretical predictions for the measured quantities is presented.

The advent of lithium-ion battery technology in portable electronic devices and electric vehicle applications results in the generation of millions of hazardous e-wastes that are detrimental to the ecosystem. A proper closed-loop recycling protocol reduces the environmental burden and strengthens a country with resource sustainability, circular economy, and the provision of raw materials. However, to date, only 3% of spent LIBs have been recycled. The recycling efficiency can be further increased upon strong policy incentives by the government and legislative pressure on the collection rate. This review sheds light on the pretreatment process of end-of-life batteries that includes storage, diagnosis, sorting, various cell discharge methods ( e.g. , liquid medium, cryogenic and thermal conditioning, and inert atmosphere processing), mechanical dismantling (crushing, sieving, sequential, and automated segregation), and black mass recovery (thermally and solvent leaching). The advantage of the stagewise physical separation and practical challenges are analyzed in detail. Disassembling the battery module pack at the cell level with the improved technology of processing spent batteries and implementing artificial intelligence-based automated segregation is worth it for high-grade material recovery for battery applications. Herein, we outline an industry-viable mechanochemical separation process of electrode materials in a profitable and ecofriendly way to mitigate the energy demand in the near future.

Since 2011, 2D transition metal carbides, carbonitrides and nitrides known as MXenes have gained huge attention due to their attractive chemical and electronic properties. The diverse functionalities of MXenes make them a promising candidate for multitude of applications. Recently, doping MXene with metallic and non-metallic elements has emerged as an exciting new approach to endow new properties to this 2D systems, opening a new paradigm of theoretical and experimental studies. In this review, we present a comprehensive overview on the recent progress in this emerging field of doped MXenes. We compare the different doping strategies; techniques used for their characterization and discuss the enhanced properties. The distinct advantages of doping in applications such as electrocatalysis, energy storage, photovoltaics, electronics, photonics, environmental remediation, sensors, and biomedical applications is elaborated. Additionally, theoretical developments in the field of electrocatalysis, energy storage, photovoltaics, and electronics are explored to provide key specific advantages of doping along with the underlying mechanisms. Lastly, we present the advantages and challenges of doped MXenes to take this thriving field forward.

Centrifugal spinning was utilized in producing polyacrylonitrile (PAN) nanofibers loaded with extractant di-(2-ethylhexyl) phosphoric acid (D2EHPA) for efficient adsorption recovery of gallium from aqueous solutions. The adsorption experimental data were best fitted by a pseudo-second-order kinetic model and the BET equilibrium isotherm model. Optimal adsorption performance by the PAN/D2EHPA nanofibers exhibited an adsorption capacity of 33.13 mg g−1 for the recovery of gallium at pH 2.5 and 55 °C. The thermodynamic parameters demonstrated that adsorption was endothermic, spontaneous, and favorable. The stability and reusability of the nanofibers was assessed, demonstrating retention of structural and functional integrity for the nanofibers over five cycles of an adsorption/desorption process, whilst retaining adsorption efficiency. The results demonstrate that PAN/D2EHPA nanofibers have excellent potential for utilization in an efficient adsorption process for gallium recovery, offering significant positive environmental impact over conventional liquid–liquid extraction methods.

This work demonstrates a two-step gram-scale synthesis of presynthesized silver (Ag) nanoparticles impregnated with mesoporous TiO2 and evaluates their feasibility for wastewater treatment and hydrogen gas generation under natural sunlight. Paracetamol was chosen as the model pharmaceutical pollutant for evaluating photocatalytic performance. A systematic material analysis (morphology, chemical environment, optical bandgap energy) of the Ag/TiO2 photocatalyst powder was carried out, and the influence of material properties on the performance is discussed in detail. The experimental results showed that the decoration of anatase TiO2 nanoparticles (size between 80 and 100 nm) with 5 nm Ag nanoparticles (1 wt %) induced visible-light absorption and enhanced charge carrier separation. As a result, 0.01 g/L Ag/TiO2 effectively removed 99% of 0.01 g/L paracetamol in 120 min and exhibited 60% higher photocatalytic removal than pristine TiO2. Alongside paracetamol degradation, Ag/TiO2 led to the generation of 1729 smol H2 g-1 h-1. This proof-of-concept approach for tandem pollutant degradation and hydrogen generation was further evaluated with rare earth metal (lanthanum)-and nonmetal (nitrogen)-doped TiO2, which also showed a positive response. Using a combination of ab initio calculations and our new theory model, we revealed that the enhanced photocatalytic performance of Ag/TiO2 was due to the surface Fermi-level change of TiO2 and lowered surface reaction energy barrier for water pollutant oxidation. This work opens new opportunities for exploiting tandem photocatalytic routes beyond water splitting and understanding the simultaneous reactions in metal-doped metal oxide photocatalyst systems under natural sunlight.

Inorganic–organic hybrid perovskite solar cells, a low-cost viable substitute to conventional silicon technology, have seen an unparalleled efficiency improvement within a span of few years due to their unique tunable properties and ease of fabrication methodology. These hybrid structures are greatly influenced by nanomaterials/nanostructures in enhancing their properties. Nanostructures implemented into sensitizing, hole transporting and electron selective layers in these devices, aid to increasing surface area-to-volume ratio, facilitate charge accumulation, and transport through interfaces. Nanocarbons are seen as potential alternatives to organic hole conductors, boasting inexpensive earth-abundant components, and good stability. Perovskite photovoltaic devices have prospects of becoming an important source of clean energy devices, or even powering portable devices.

With growing environmental consciousness, biomaterials (BMs) have garnered attention as sustainable materials for the adsorption of hazardous water contaminants. These BMs are engineered using surface treatments or physical alterations to enhance their adsorptive properties. The lab-scale methods generally employ a One Variable at a Time (OVAT) approach to analyze the impact of biomaterial modifications, their characteristics and other process variables such as pH, temperature, dosage, etc. , on the removal of metals via adsorption. Although implementing the adsorption procedure using BMs seems simple, the conjugate effects of adsorbent properties and process attributes implicate complex nonlinear interactions. As a result, artificial neural networks (ANN) have gained traction in the quest to understand the complex metal adsorption processes on biomaterials, with applications in environmental remediation and water reuse. This review discusses recent progress using ANN frameworks for metal adsorption using modified biomaterials. Subsequently, the paper comprehensively evaluates the development of a hybrid-ANN system to estimate isothermal, kinetic and thermodynamic parameters in multicomponent adsorption systems.

Hybrid power infrastructure is often viewed as an alternative system configuration for off-grid telecom base stations. These systems are used to reduce the fuel consumption of diesel generator sites and often rely on wind or solar to supplement some of the power to the load. The ability of a site to use the renewable energy efficiently becomes more critical on sites where the quality of the wind or solar resource is poor or highly variable. The long term and short term effects of wind and solar power contributions to the system are demonstrated using historical wind speed/solar irradiation data over a 3 year period. A feasible approach is proposed to improve the efficiency of the system by analysing the rate of change of the renewable energy source(s). Using several successive measurements, the battery charging system can be restrained temporarily to allow for the initial stages of diurnal weather patterns. These patterns may later negate the need for the charging cycle which can result in wasted power should a renewable power source increase its power output during a generator charging cycle.

BiVO 4 is a well-known n-type semiconductor with great potential for photoelectrochemical (PEC) conversion of solar energy into chemical fuels. Nevertheless, photocurrent densities achieved for bare BiVO 4 photoanodes are still far from their theoretical maximum due to the sluggish water oxidation kinetics and limitation in electron-hole recombination. In this work, magnetron sputtering deposition was used for depositing FeMO x (M = Ni, Mn) as cocatalyst layers to induce p–n heterojunctions and suppress charge recombination on BiVO 4 photoanodes. The all-sputtered p–n heterojunction BiVO 4 /FeMnO x exhibited the highest photocurrent density (1.25 mA cm −2 at 1.23 V vs. RHE) and excellent chemical stability, indicating that the combination of Mn sites on Fe-based oxides provides promising cocatalytic materials for PEC applications. Experimental and theoretical techniques were used to investigate the interfacial band alignment and charge transport properties of BiVO 4 /FeMO x (M = Ni, Mn) heterojunctions. Our results show that type II heterojunctions arise in the BiVO 4 /FeMO x (M = Ni, Mn) interface after equilibrium, thereby providing potential barriers to inhibit electron flow from the BiVO 4 to the FeMO x layers. Furthermore, the BiVO 4 /FeMnO x film showed a larger space charge region (SCR) characterized by a more intense built-in electric field than BiVO 4 /FeNiO x , explaining its higher PEC performance. In summary, this work provides a viable technique for producing photocatalytic heterojunction systems based on metal oxide semiconductors and introduces simple tools for investigating interface effects on photoinduced charge carrier pathways for PEC applications.

Selection and utilization of multifaceted coating materials for progressing aerospace and defence technologies that operate in stringent service environments are always challenging. Nevertheless, conventional coatings exhibit limited strength, flexibility, durability, and poor substrate-coating adhesion when exposed to extreme adverse temperatures, formidable fatigue and creep, huge vacuum, and swift velocity. Currently, researchers are increasingly attracted towards the newly emerging single-layered (2D) materials for their structure-property relationship to utilize them as a protective coating that renders prospective outcomes for these concerns. Therefore, this review focuses on various attributes of the atomically thin-Angstrom scale 2D materials such as MXene, hexagonal-BN, graphene, transition metal dichalcogenides (TMD) including WS2, MoS2, TiN, and WSe2, black phosphorous, and borophenes. A thorough investigation of their lower thermal conductivity (0.16 to 1.752W/m/K) when operated between -10°C and an elevated temperature of 1100°C offering exceptional thermal barrier effects, the ultra-low coefficient of friction (0.06 to 0.6) under different sliding conditions inducing excellent anti-wear/anti-friction behaviour, and the minimum corrosion rate (2.24 × 10-3 to 0.086mm per year) in varying atmospheric conditions instigating corrosion passivation of the 2D nanomaterials deposited over metallic substrate have been elucidated. These exceptional properties of atomically thin nanomaterials can be potentially utilized in engine components, piston-cylinder linings, and landing gears of aerospace systems, heat exchangers, flanges, and impellers in the marine sector and potentially utilised in muzzle, recoil springs, and barrels of armament technologies. [Display omitted]

Alkyl-modified silicon nanocrystallites are efficient fluorophores which are of interest for fundamental spectroscopic studies and as luminescent probes in biology because of their stability in aqueous media. In this work we have investigated these particles using scanning tunneling microscopy, synchrotron-radiation excited photoemission, and x-ray excited optical luminescence (XEOL). During the course of illumination with 145 - eV photons we have monitored the evolution of the Si 2 p core level and, in samples which have suffered prolonged atmospheric exposure, observed in real time the growth of an extra Si 2 p component attributed to in situ photoinduced oxidation of the Si nanocrystallites. XEOL reveals that two emission bands are active upon soft-x-ray photon excitation and that photoluminescence intensity decreases with photon exposure, which is attributed to charge trapping within the film.

Printing of nanostructured films with tailored oxidation state and electronic structure can have far reaching applications in several areas including printable electronics, optoelectronics, solar cells, catalytic conversion, and others. Widely used inkjet/aerosol/screen printing techniques require pre- and postprocessing for enhanced adhesion and tailoring of the chemical state of the thin film. Herein, we demonstrate atmospheric pressure plasma jet printing with unique capability to print and tune in situ the electronic properties and surface morphology of nanomaterials. Plasma printing of copper thin films with tailored oxidation state from an inexpensive copper oxide precursor is demonstrated and characterized using x-ray absorption spectroscopy, Raman spectroscopy, and electrical measurements. Published by the AVS.

The release of crude oil and water-soluble dyes into our marine environment is a major global problem. An efficient semiconductor Ag-Ag3PO4 photocatalyst was synthesized using formaldehyde as a reducing agent to form surface active Ag on Ag3PO4 under microwave radiation for heating, and its potential in destroying environmental pollutants has been examined. The diffuse reflectance spectroscopy of Ag-Ag3PO4 revealed an enhanced absorption in the visible light region. The rate of photocatalytic degradation of rhodamine B by Ag-Ag3PO4 was over 4-fold compared to Ag3PO4 . The potential application of Ag-Ag3PO4 in oil spill remediation was also examined through photocatalytic degradation of benzene, n-hexane, and 1:1 v/v benzene/methanol crude oil-soluble fractions. UV-vis and gas chromatography-mass spectrometry analysis of the crude oil components after visible light irradiation showed excellent degradation. The photocatalytic efficiency enhancement of Ag-Ag3PO4 is attributed to the excellent electron trapping of silver nanoparticles deposited on the surface of Ag3PO4 . This work will motivate future studies to develop recyclable visible light photocatalysts for many applications.

The electronic properties of cobalt-doped ZnO were investigated through site-selective and element-sensitive x-ray-absorption spectroscopy in the vicinity of the Co L2,3 edge, the oxygen K edge, and at the Zn L3 edge. The spectroscopic measurements of the ferromagnetic cobalt-doped ZnO films appear to have additional components in the O K edge x-ray-absorption spectrum not observed in the undoped films. The observed features may derive from both hybridization with unoccupied Co 3d states and also from lattice defects such as oxygen vacancies. Only minor changes in the Zn L3 edge spectra were observed. These observations are consistent with a polaron percolation model in which the ferromagnetic coupling is mediated by shallow donor electrons trapped in oxygen vacancies and couples the Co atoms substituted on Zn sites in the hexagonal wurtzite ZnO structure.

Atmospheric pressure plasma functionalisation of CuO thin films transforms surfaces to superhydrophillic, lowers surface potential, boosts electro and photo catalytic activities. [Display omitted] •Fast and environment friendly route to engineer CuO thin film surfaces.•Low power atmospheric pressure plasma jet transforms CuO surface superhydrophilic.•Plasma functionalisation boosts electro and photocatalytic activities.•Presence of oxygen radicals critical for the enhanced activities.•Energetic species in plasma perturbs the local electronic and lattice structure. Cupric oxide (CuO) thin film has found widespread application as a low-cost, earth-abundant material for electro and photo catalytic applications. High surface wettability is a key factor to achieve enhanced efficiency in these catalytic applications. Here, we report a fast and environment friendly route to fabricate super hydrophilic CuO thin films using a low power (5–10 W) atmospheric pressure plasma jet (APPJ). With APPJ treatment for 5 min, the CuO surface transforms from hydrophobic to super-hydrophilic with threefold increase in catalytic activity. The electrodes were extensively characterized using various bulk and surface-sensitive techniques. APPJ introduces anisotropy in the crystal structure and creates unique three-dimensional surface morphology with distinct surface chemical and electronic features. Interestingly, presence of oxygen in the plasma was found to be critical for the enhanced activities and the activity decreased when the functionalised with nitrogen plasma. Oxygen plasma functionalisation of CuO electrodes resulted in a 130 mV reduction in the onset potential for oxygen evolution reaction along with enhanced current density, 10 mA cm−2 against 3 mA cm−2 at 1 V vs Saturated Calomel Electrode in 0.1 M KOH without iR compensation. Importantly, without introducing any external dopants the work function could be decreased by 80 mV. Moreover, the treated films exhibited a higher rate of photo degradation (0.0283 min−1 compared to 0.0139 min−1) of Methylene Blue and phenol indicating efficient charge separation. This work presents the potential of APPJ functionalisation of CuO surface to boost the activity of other thin film catalyst materials and solutions processed systems.

Gold films containing gold nitride have been produced by nitrogen reactive ion sputtering and characterized by X-ray photoemission spectroscopy. N1s core-level spectra from the films show a peak at 397.0 +/- 0.2 eV attributed to gold nitride species. The intensity of the nitride peak decays with measurement time, demonstrating that this material decomposes under X-ray irradiation. Atomic force microscopy shows that the nitride containing films are also sensitive to electron beam irradiation, indicating that X-ray or electron beam lithography may be used to directly write patterns on a gold nitride surface. (c) 2006 Published by Elsevier B.V.

Zinc oxide (ZnO) nanostructures of various morphologies were produced in an aqueous system, with pyridine as a shape-directing agent. X-ray diffraction (XRD) and selected-area electron diffraction (SAED) revealed hexagonal wurtzite crystal structure. Variation in surface morphology was analyzed using transmission electron microscopy (TEM). Changes in surface morphology were attributed to the absence of steric stabilization in pyridine during synthesis process. Pyridine concentration affected morphology and optical properties. Fourier transform infrared spectroscopy (FTIR) confirmed the presence/absence of pyridine on the surface of ZnO nanostructures (ZnO-NSs). Optical measurements carried out using UV-visible spectrophotometer (UV-vis) and photoluminescence (PL) indicated the presence of defects. All the samples exhibited two PL peaks, at 350-370 nm and 560-624 nm. Variation in the intensities of PL peaks corresponded to the changes in the surface morphology from nanoparticles to rods and origin of deep-level defect luminescence is attributed to surface recombination. The toxicity of the nanostructures was tested on model Gram-negative and Gram-positive pathogens. Smaller nanorods were most toxic among the nanostructures tested. (C) 2013 Elsevier B.V. All rights reserved.

Nanosized metal germanates (M2GeO4; M=Co, Mn, Zn) are synthesized using a continuous hydrothermal flow synthesis process for the first time. The electrochemical properties of all samples as active materials for negative electrodes in Li-ion half cells are explored. The galvanostatic and potentiodynamic testing is conducted in the potential range of 3.00-0.05V versus Li/Li+. The results suggest that both alloying and conversion reactions associated with Ge contribute to the stored charge capacity; Zn2GeO4 shows a high specific capacity of 600mAhg(-1) (ten cycles at 0.1Ag(-1)) due to alloying and conversion reactions for both Ge and Zn. Mn2GeO4 is studied for the first time as a potential negative electrode material in a Li-ion half cell; an excellent specific charge capacity of 510mAhg(-1) (10 cycles per 0.1Ag(-1)) is obtained with a significant contribution to charge arising from the conversion reaction of Mn to MnO upon delithiation. In contrast, Co2GeO4 only shows a specific capacity of 240mAhg(-1), after ten cycles at the same current rate, which suggests that cobalt has little or no benefit for enhancing stored charge in germanate.

Pesticides are unavoidable in agriculture to protect crops from pests and insects. Organophosphates (OPs) are a class of pesticides that are more harmful because of the irreversible inhibition reaction with acetylcholinesterase enzyme, thereby posing serious health hazards in human beings. In the present work, a sensitive and selective immuno-sensing platform is developed using gold inter-digitized electrodes (Au-IDEs) as substrates, integrated with a microfluidic platform having the microfluidic well capacity of 10 mu L. Au-IDE having digit width of 10 mu m and gap length of 5 mu m was used in this study. The surface morphological analysis by field-effect scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM) revealed the direct information regarding the modification of Au-IDEs with anti-parathion (Anti-PT) antibodies. In SEM analysis, it was seen that the Au-IDE surface was smooth in contrast to the Anti-PT modified surface, which is supported by the AFM studies showing the surface roughness of similar to 2.02 nm for Au-IDE surface and similar to 15.86 nm for Anti-PT modified surface. Further, Fourier transform infra-red (FTIR) spectroscopic analysis confirms the immobilization of Anti-PT by the bond vibrations upon the successive modification of Au-IDE with -OH groups, amine groups after modifying with APTES, and the amide bond formation after incubation in Anti-PT antibody. Electrochemical impedance spectroscopy (EIS) was carried out for the electrochemical characterization and for testing the sensing performances of the fabricated electrode. The developed immuno-sensor provided a linear range of detection from 0.5 pg/L-1 mu g/L, with a limit of detection (LoD) of 0.66 ng/L and sensitivity of 4.1 M omega/ngL(-1)/cm(2). The sensor response was also examined with real samples (pomegranate juice) with good accuracy, exhibiting a shelf life of 25 days. The miniaturized sensing platform, along with its better sensing performance, has huge potential to be integrated into portable electronics, leading to suitable field applications of pesticide screening devices.

The production of hydrogen (H-2) through photoelectrochemical water splitting (PEC-WS) using renewable energy sources, particularly solar light, has been considered a promising solution for global energy and environmental challenges. In the field of hydrogen-scarce regions, metal oxide semiconductors have been extensively researched as photocathodes. For UV-visible light-driven PEC-WS, cupric oxide (CuO) has emerged as a suitable photocathode. However, the stability of the photocathode (CuO) against photo-corrosion is crucial in developing CuO-based PEC cells. This study reports a stable and effective CuO and graphene-incorporated (Gra-COOH) CuO nanocomposite photocathode through a sol-gel solution-based technique via spin coating. Incorporating graphene into the CuO nanocomposite photocathode resulted in higher stability and an increase in photocurrent compared to bare CuO photocathode electrodes. Compared to cuprous oxide (Cu2O), the CuO photocathode was more identical and thermally stable during PEC-WS due to its high oxidation number. Additionally, the CuO:Gra-COOH nanocomposite photocathode exhibited a H-2 evolution of approximately 9.3 mu mol, indicating its potential as a stable and effective photocathode for PEC-WS. The enhanced electrical properties of the CuO:Gra-COOH nanocomposite exemplify its potential for use as a charge-transport layer.

ZnO thin films deposited on various substrates were characterized by slow positron implantation spectroscopy (SPIS) combined with X-ray diffraction (XRD). All films studied exhibit wurtzite structure and crystallite size 20-100 nm. The mosaic spread of crystallites is relatively small for the films grown on single crystalline substrates while it is substantial for the film grown on amorphous substrate. SPIS investigations revealed that ZnO films deposited on single crystalline substrates exhibit significantly higher density of defects than the film deposited on amorphous substrate. This is most probably due to a higher density of misfit dislocations, which compensate for the lattice mismatch between the film and the substrate.

Unique porous carbon monoliths containing thermally annealed carbon onions, were prepared from a resorcinol formaldehyde precursor rod, containing silica gel acting as a hard template, detonation nanodiamond, and Fe3+ as a graphitisation catalyst. Detonation nanodiamond was converted to carbon onions during controlled pyrolysis under N-2, where the temperature cycle reached a maximum of 1250 degrees C. Thermal characterisation and high resolution electron microscopy have confirmed the graphitisation of nanodiamond, and revealed the resulting quasi-spherical carbon onions with an average particle size of 5.24 nm. The bimodal porous composite contains both macropores (5 mu m) and mesopores (10 nm), with a BET surface area of 214 m(2) g(-1) for a nanodiamond prepared monolith (0.012 wt% nanodiamond in the precursor mixture), approximately twice that of blank monoliths, formed without the addition of nanodiamond, thus providing a new approach to increase surface area of such porous carbon rods. Raman spectroscopy and X-ray photoelectron spectroscopy also confirmed an enhanced graphitisation of the monolithic carbon skeleton resulting from the elevated thermal conductivity of the added nanodiamond. TEM imaging has confirmed the nanodiamond remains intact following pyrolysis at temperatures up to 900 degrees C.

We report systematic investigations on structural and magnetic properties of nanosized NiO powders prepared by the ball milling process followed by systematic annealing at different temperatures. Both as milled and annealed NiO powders exhibit face centered cubic structure, but average crystallite size decreases (increases) with increasing milling time (annealing temperature). Pure NiO exhibits anti ferromagnetic nature, which transforms into ferromagnetic one with moderate moment at room temperature with decreasing crystallite size. The on set of ferromagnetic behavior in the as milled powders was observed at higher temperatures > 750 K) as compared to bulk Ni ( 630 K). On the other hand, annealing of as milled powders showed a large reduction in magnetic moment and the rate of decrease of moment strongly depends on the milling conditions. The observed properties are discussed on the basis of crystallite size variation, defect density, oxidation/reduction of Ni and interaction between uncompensated surfaces and particle core with lattice expansion. (C) 2015 Elsevier B.V. All rights reserved

Resonant inelastic x-ray scattering (RIXS), x-ray absorption spectroscopy and x-ray excited optical luminescence (XEOL) have been used to measure element specific filled and empty electronic states over the Si L-2,L-3 edge of passivated Si nanocrystals of narrow size distribution ( diameter 2.2 +/- 0.4 nm). These techniques have been employed to directly measure absorption and luminescence specific to the local Si nanocrystal core. Profound changes occur in the absorption spectrum of the nanocrystals compared with bulk Si, and new features are observed in the nanocrystal RIXS. Clear signatures of core and valence band exciton formation, promoted by the spatial confinement of electrons and holes within the nanocrystals, are observed, together with band narrowing due to quantum confinement. XEOL at 12 K shows an extremely sharp feature at the threshold of orange luminescence (i.e., at similar to 1.56 eV ( 792 nm)) which we attribute to recombination of valence excitons, providing a lower limit to the nanocrystal band gap.

Thin films of AlN, CrN and Al1-xCrxN were grown epitaxially on c-cut sapphire by radio frequency (RF) plasma assisted pulsed laser deposition (PLD). The PLD growth mode employed for these Al1-xCrxN films was by delta doping layers of CrN 0.05-0.10 nm thick between layers of AlN of approximately 3.6 nm thick giving an estimated 1.3% and 2.5% Cr doping. The substrate temperature, nitrogen pressure and power parameters of the RF plasma were varied to optimize crystalline growth. X-ray diffraction (XRD) confirmed hexagonal wurtzite thin film growth of highly crystalline AlN and highly crystalline cubic CrN. The electronic structure of these thin films was examined by x-ray absorption (XAS) and soft x-ray emission spectroscopy (XES) at the N K edge. These measurements are compared with the results of density functional calculations for wurtzite-AlN, cubic-CrN and wurtzite-Al1-xCrxN.

•Liquid Phase – Pulsed Laser Ablation (LP-PLA) was applied for carbon nanostructures fabrication.•LP-PLA was applied at a higher frequency than previously presented for CNP fabrication.•Higher energy densities resulted in nanoparticles with smaller sizes (42 to 75nm).•Onion like carbon was produced for specific laser processing settings.•CNPs below 200nm and MWCNT above 200nm were produced. Carbon nanostructures in various forms and sizes, and with different speciation properties have been prepared from graphite by Liquid Phase – Pulsed Laser Ablation (LP-PLA) using a high frequency Nd:YAG laser. High energy densities and pulse repetition frequencies of up to 10kHz were used in this ablation process to produce carbon nanomaterials with unique chemical structures. Dynamic Light Scattering (DLS), micro-Raman and High-Resolution Transmission Electron Microscopy (HRTEM) were used to confirm the size distribution, morphology, chemical bonding, and crystallinity of these nanostructures. This article demonstrates how the fabrication process affects measured characteristics of the produced carbon nanomaterials. The obtained particle properties have potential use for various applications including biochemical speciation applications.

The thermally driven reaction of carbon nanotubes with a silicon substrate is studied by photoemission spectroscopy and atomic force microscopy. Carbon nanotubes with a relatively high defect density are observed to decompose under reaction with silicon to form silicon carbide at temperatures (650±10 °C) substantially lower than the analogous reaction for adsorbed C60. The morphology of the resultant silicon carbide islands appears to reflect the morphology of the original nanotubes, suggesting a means by which SiC nanostrutures may be produced.

Over 80% of wastewater worldwide is released into the environment without proper treatment. Whilst environmental pollution continues to intensify due to the increase in the number of polluting industries, conventional techniques employed to clean the environment are poorly effective and are expensive. MXenes are a new class of 2D materials that have received a lot of attention for an extensive range of applications due to their tuneable interlayer spacing and tailorable surface chemistry. Several MXene‐based nanomaterials with remarkable properties have been proposed, synthesized, and used in environmental remediation applications. In this work, a comprehensive review of the state‐of‐the‐art research progress on the promising potential of surface functionalized MXenes as photocatalysts, adsorbents, and membranes for wastewater treatment is presented. The sources, composition, and effects of wastewater on human health and the environment are displayed. Furthermore, the synthesis, surface functionalization, and characterization techniques of merit used in the study of MXenes are discussed, detailing the effects of a range of factors (e.g., PH, temperature, precursor, etc.) on the synthesis, surface functionalization, and performance of the resulting MXenes. Finally, the limits of MXenes and MXene‐based materials as well as their potential future research directions, especially for wastewater treatment applications are highlighted. 2D nanomaterials, especially MXenes have recently seen exciting developments in research and development, and their application in wastewater treatment has drawn wider attention. This review examines state‐of‐the‐art strategies employed in synthesis, functionalization, and characterization of surface functionalized MXenes. Furthermore, engineering strategies like composition design, and how surface protection influence their properties as adsorbents, photocatalysts, and membranes in wastewater treatment are discussed.

Herein, it is demonstrated that incorporating ultrathin p-type cupric oxide (CuO) enhances the performance and stability of solution-processed Cu-2(Zn0.6Cd0.4)SnS4 (CZCTS)/CdS thin film solar cells. In sol-gel CZCTS/CdS thin film solar cells, nanoscale CuO films (4-32 nm) are deposited on top of molybdenum (Mo) by magnetron sputtering and this is used as an intermediate layer (IL). The CuO IL thickness has a significant effect on the short-circuit current density (J(sc)) in CZCTS/CdS solar cell devices. As a result, a maximum power conversion efficiency (PCE) of 10.77% is measured for the optimized device with 4 nm CuO compared with 10.03% for the reference device without a CuO layer. Furthermore, the stability of the devices is enhanced significantly by incorporating the CuO IL. This work demonstrates that through proper design of the CuO IL thickness, both the back interface quality and optical property of the CZCTS absorber can be tuned to enhance the device performance.

The nitration of gold surfaces is a nonpolluting method, which can lead to large scale production of substrates with remarkable properties and applications. We present a topographical study of the nanoscale structure of the gold nitride surfaces produced by radio frequency (rf) nitrogen plasma etching of thin gold films. Atomic force microscopy images taken after rf etching reveal the striking appearance of the cluster assembly with large clusters surrounded by small clusters (7.9 +/- 1.4 and 2.3 +/- 0.9 nm, respectively) appearing to exhibit an attractive interaction. We discuss the possible mechanism for this attraction based on a colloid model by Messina [Phys. Rev. Lett. 85, 872 (2000)]. This surface exhibits a notable surface enhanced Raman scattering effect demonstrated with L-alanine and rhodamine-6G. The significance of this work is that we found that this SERS active gold nitride surface can be prepared in just one step: by nitrogen plasma etching a thin gold film. Until now most SERS active gold cluster covered surfaces have been prepared in several steps very often requiring complex lithography.

Electroactive biofilms are capable of extracellular electron transfer to insoluble metal oxides and electrodes; such biofilms are relevant to biogeochemistry, bioremediation, and bioelectricity production. We investigated the extracellular electron transfer mechanisms in Shewanella loihica PV-4 viable biofilms grown at indium tin oxide (ITO) and graphite electrodes in potentiostat-controlled electrochemical cells poised at 0.2 V vs. Ag/AgCl. Chronoamperometry and confocal microscopy showed higher biofilm growth at graphite compared to the ITO electrode. Cyclic voltammetry, differential pulse voltammetry, along with fluorescence spectroscopy showed that direct electron transfer through outer membrane c type cytochromes (Omcs) prevailed at the biofilm/ITO interface, while biofilms formed at graphite electrode reduced the electrode also via secreted redox mediators, such as flavins and quinones. The biofilm age does not affect the prevalent transfer mechanism at ITO electrodes. On the other hand, secreted redox mediators accumulated at biofilm/graphite interface, thus increasing mediated electron transfer as the biofilm grows over five days. Our results showed that the electrode material determined the prevalent electron transfer mechanism and the dynamic of secreted redox mediators in S. loihica PV-4 biofilms. These observations have implications for the optimization of biofilm-based electrochemical systems, such as biosensors and microbial fuel cells.

Here, we report the successful coupling of La doped MnO2 nanorods (30 nm mean diameter and 1 mu m mean length) with multiwalled carbon nanotubes (CNTs) via a simple in situ hydrothermal method to form a La3+:MnO2-CNT nanohybrid as well as a systematic investigation of the influence of the dopant concentration on its performance as an electrode for supercapacitors. X-ray diffraction, electron microscopy and energy dispersive X-ray analysis revealed the formation of MnO2 nanorods uniformly distributed within the CNT network. The electrochemical measurements revealed a strong positive influence of the La dopants on the performance of the MnO2-CNT nanohybrid for up to 2 mol% La, above which the performance degraded. Thus, the 2 mol% La3+:MnO2-CNT nanohybrid sample was identified as the best electrode material in this study which exhibited a specific capacitance of similar to 1530 F g(-1) at a current density of 1 A g(-1) along with a charge retention of 92% after 5000 cycles which are both much higher than those reported previously for MnO2 based supercapacitor electrodes and thus, is a leap towards using MnO2 as a low-cost electrode for supercapacitors. The enhanced performance of the optimised 2 mol% La3+:MnO2-CNT nanohybrid originated from the combinatorial influence of the material selection, the optimised concentration of La dopants and the synergistic influence of CNTs that resulted in its lowest charge transfer resistance and highest diffusion coefficient.

In the present study, pristine BiVO4, TiO2 and BiVO4/TiO2 core-shell heterostructured nanoparticles are prepared by hydrothermal methods and studied for structural, morphological, optical, photoelectrochemical water splitting and photocatalytic degradation of methylene blue as an organic pollutant. Both pristine BiVO4 and TiO2 exhibit poor PEC and PC performance under visible light illumination. However, an enhanced PEC and PC activity in BiVO4/TiO2 core-shell heterostructure is observed due to high solar energy absorption and superior charge separation properties in core-shell nanoparticles. The photoelectrode prepared using BiVO4/TiO2 core-shell nanoparticles exhibit a photocathode behavior and produced cathodic photocurrent, however, the pristine BiVO4 and TiO2 photoelectrodes act as photoanode and produced anodic photocurrent. This behavior of change in current direction is also observe in the Mott-Schottky analysis where the BiVO4/TiO2 core-shell nanoparticles photoelectrode exhibits the positive slow showing p-type semiconducting behavior. The change in cathodic photoresponse in core-shell nanoparticles in comparison to anodic photoresponse of BiVO4 and TiO2 nanoparticles is explained in terms of the variations in the work function values. These results highlight the advantages of core-shell nanoparticle of suitable materials for photocatalytic and photo-electrochemical applications. (C) 2020 Elsevier Ltd. All rights reserved.

Tin dioxide (SnO 2 ), the most stable oxide of tin, is a metal oxide semiconductor that finds its use in a number of applications due to its interesting energy band gap that is easily tunable by doping with foreign elements or by nanostructured design such as thin film, nanowire or nanoparticle formation, etc. , and its excellent thermal, mechanical and chemical stability. In particular, its earth abundance and non-toxicity make it very attractive for use in a number of technologies for sustainable development such as energy harvesting and storage. This article attempts to review the state of the art of synthesis and properties of SnO 2 , focusing primarily on its application as a transparent conductive oxide (TCO) in various optoelectronic devices and second in energy harvesting and energy storage devices where it finds its use as an electron transport layer (ETL) and an electrode material, respectively. In doing so, we discuss how tin oxide meets the requirements for the above applications, the challenges associated with these applications, and how its performance can be further improved by adopting various strategies such as doping with foreign metals, functionalization with plasma, etc. The article begins with a review on the various experimental approaches to doping of SnO 2 with foreign elements for its enhanced performance as a TCO as well as related computational studies. Herein, we also compare the TCO performance of doped tin oxide as a function of dopants such as fluorine (F), antimony (Sb), tantalum (Ta), tungsten (W), molybdenum (Mo), phosphorus (P), and gallium (Ga). We also discuss the properties of multilayer SnO 2 /metal/SnO 2 structures with respect to TCO performance. Next, we review the status of tin oxide as a TCO and an ETL in devices such as organic light emitting diodes (OLEDs), organic photovoltaics (OPV), and perovskite solar cells (including plasma treatment approaches) followed by its use in building integrated photovoltaic (BIPV) applications. Next, we review the impact of SnO 2 , mainly as an electrode material on energy storage devices starting from the most popular lithium (Li)-ion batteries to Li–sulfur batteries and finally to the rapidly emerging technology of supercapacitors. Finally, we also compare the performance of doped SnO 2 with gallium (Ga) doped zinc oxide (ZnO), the main sustainable alternative to SnO 2 as a TCO and summarize the impact of SnO 2 on circular economies and discuss the main conclusions and future perspectives. It is expected that the review will serve as an authoritative reference for researchers and policy makers interested in finding out how SnO 2 can contribute to the circular economy of some of the most desired sustainable and clean energy technologies including the detailed experimental methods of synthesis and strategies for performance enhancement.

We report on a systematic investigation of the electronic properties of UV-light emitting Zn doped CuCl thin films implemented using near edge x-ray absorption fine structures (NEXAFS) and high-resolution x-ray photoemission spectroscopy. A clear shift of the valence band maximum towards higher binding energy by 0.2 +/- 0.1 eV was observed in Zn doped CuCl as compared to undoped CuCl. This shift is in correlation with the increase in conductivity measured by the Hall effect measurements. A decrease in the optical band gap of CuCl film is also observed as a function of Zn doping. The profound changes in the full width at half maximum and the gradual disappearance of satellite features of Cu 2p core level photoemission as a function of Zn dopant are attributed to the reduced presence of the surface layer of Cu2+ species with d(9) configuration in the doped films. These investigations help us to understand the doping mechanisms and underlying physics. The reduced presence of the Cu2+ related surface layer as a function of Zn doping is also verified using NEXAFS.

In this study thin film samples of Ga1-xMnxN were grown by pulsed laser deposition on Al2O3 (0001) substrates. Xray diffraction measurements have confirmed these thin films exhibit hexagonal wurtzite structure. SQUID measurements show room temperature ferromagnetism of these dilute magnetic semiconductors (DMS). The techniques of X-ray absorption and soft X-ray emission spectroscopy at the N K-edge were used to study the changes in the unoccupied and occupied N 2p partial density of states respectively as a function of dopant concentration. These element and site specific spectroscopies allow us to characterise the electronic structure of these doped materials and reveal the influence of the Mn doping on the valence band as measured through the N 2p partial density of states. X-ray absorption measurements at the Mn L-edge confirm significant substitutional doping of Mn into Ga-sites. Finally, measurements of heavily Mn-doped films using both soft X-ray absorption and resonant soft X-ray emission at the N K edge reveal the presence of trapped molecular nitrogen. The trapped molecular nitrogen may be due to the high instantaneous deposition rate in the PLD process for these samples. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

10.5 lakh tonnes of caustic soda is produced in India based on the membrane cell technology. Though membrane cells require 700 KWh lesser electrical energy per tonne of caustic, they produce caustic of concentration 32-33 wt%, which has to be concentrated to 45-46 wt% to meet the needs of the consumers. Concentration is now being done by thermal evaporators. Every tonne of 32-33 wt% caustic requires 0.75 tonne of steam for concentration. 8 lakh tonnes of steam is being consumed per annum for this purpose. In the present paper an electrochemical concentrator is proposed to replace the thermal evaporators.

In the present study structural, optical and electronic properties of bismuth vanadate (BiVO4) thin films prepared by rf-sputtering technique were modified by post-hydrogen treatment to improve the photoelectrochemical (PEC) performance for water oxidation. X-ray diffraction and Raman analysis do not reveal any major structural changes but show increase in crystallite size and creation of defect states, however, optical absorption studies shows changes in band gap energy values due to the creation of inter-band states on hydrogen treatment. X-ray photoelectron spectroscopy studies show that the hydrogen treatment reduces surface Bi4+ considerably and increases the density of hydroxyl groups on the BiVO4 surface. The combined effect of these changes manifests in terms of enhanced photocurrent density of 3.31 mA/cm(2) (at applied potential 1.0 V versus Ag/AgCl), which is about nine time higher than the pristine BiVO4 and reduced photocurrent onset potential. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

ABSTR A C T The present review article will outline alternative uses of sugar beet pulp residue produced during the prepa-ration of sugar from sugar beet. Traditionally, sugar beet pulp has been used as cattle fodder and was not considered to have much potential to be utilised in other competitive industries such as bio-energy, polymer composites, water purification industries, etc. However, with technological advancement, sugar beet pulps have been successfully employed to reinforce polymer composites, extract nano elements, and bio-adsorb contami-nants from wastewater or as precursor molecules to create various bio-chemicals. As per the data from the Food and Agriculture Association of United States (FAAU, 2019), the e sugar beet production is very much lower (85.71% approx.) compared to sugar cane. However, in near future, because of increasing demands of sugar from the growing world population and also due to shortage of freshwater re-sources, we may anticipate bulk production of sugar beet (which requires less freshwater resources than cane sugar and whose production as per FAAU data has increased inconsistently about 1.74% approx. in last five years, in tropical regions more specifically in European countries (currently share about 69.6% of total world sugar beet production) or in other parts of the world and thus it may lead to overproduction of sugar beet pulp. Therefore, it is the need for time and efforts made by different scientists to develop new chemical technologies t can consume waste sugar beet pulps residue for the generation of different beneficial products. The promising strategies for producing multifunctional materials from sugar beet pulp include pyrolysis, enzymatic/acid hy-drolysis, surface functionalization, nanofibres extraction, stacking them as reinforcing agents in polymer com-posites and carbonization. The technologies evaluated in the present article will be of great interest to both scientists and industrialists.

Atmospheric pressure plasmas have gained attention in recent years for several environmental applications. This technology could potentially be used to deactivate airborne microorganisms, surface-bound microorganisms, and biofilms. In this work, the authors explore the efficacy of the atmospheric pressure dielectric barrier discharge (DBD) to inactivate airborne Staphylococcus epidermidis and Aspergillus niger that are opportunistic pathogens associated with nosocomial infections. This technology uses air as the source of gas and does not require any process gas such as helium, argon, nitrogen, or hydrogen. The effect of DBD was studied on aerosolized S. epidermidis and aerosolized A. niger spores via scanning electron microscopy (SEM). The morphology observed on the SEM micrographs showed deformations in the cellular structure of both microorganisms. Cell structure damage upon interaction with the DBD suggests leakage of vital cellular materials, which is a key mechanism for microbial inactivation. The chemical structure of the cell surface of S. epidermidis was also analyzed by near edge x-ray absorption fine structure spectroscopy before and after DBD exposure. Results from surface analysis revealed that reactive oxygen species from the DBD discharge contributed to alterations on the chemistry of the cell membrane/ cell wall of S. epidermidis. (C) 2017 American Vacuum Society.

•Electrochemical interaction of ZnO and AZO thin films with the enzyme glucose oxidase was studied.•Nature of interaction of GOx with AZO was explored using XPS.•Mechanism of the electron transfer between GOx and AZO/ZnO was studied using EIS.•The results show that AZO is preferable to ZnO for GOx immobilization and glucose sensor development. Al doped and undoped ZnO thin films were deposited by pulsed-laser deposition on polycarbonate sheets. The films were characterized by optical transmission, Hall effect measurement, XRD and SEM. Optical transmission and surface reflectometry studies showed good transparency with thicknesses ∼100nm and surface roughness of 10nm. Hall effect measurements showed that the sheet carrier concentration was −1.44×1015cm−2 for AZO and −6×1014cm−2 for ZnO. The films were then modified by drop-casting glucose oxidase (GOx) without the use of any mediators. Higher protein concentration was observed on ZnO as compared to AZO with higher specific activity for ZnO (0.042Umg−1) compared to AZO (0.032Umg−1), and was in agreement with cyclic voltemmetry (CV). X-ray photoelectron spectroscopy (XPS) suggested that the protein was bound by dipole interactions between AZO lattice oxygen and the amino group of the enzyme. Chronoamperometry showed sensitivity of 5.5μAmM−1cm−2 towards glucose for GOx/AZO and 2.2μAmM−1cm−2 for GOx/ZnO. The limit of detection (LoD) was 167μM of glucose for GOx/AZO, as compared to 360μM for GOx/ZnO. The linearity was 0.28–28mM for GOx/AZO whereas it was 0.6–28mM for GOx/ZnO with a response time of 10s. Possibly due to higher enzyme loading, the decrease of impedance in presence of glucose was larger for GOx/ZnO as compared to GOx/AZO in electrochemical impedance spectroscopy (EIS). Analyses with clinical blood serum samples showed that the systems had good reproducibility and accuracy. The characteristics of novel ZnO and AZO thin films with GOx as a model enzyme, should prove useful for the future fabrication of inexpensive, highly sensitive, disposable electrochemical biosensors for high throughput diagnostics.

In a study to link the optical and structural properties of solid films of magnesium Phthalocyanine, (MgPc), a range of synchrotron based spectroscopic methods have been used. These include X-ray excited optical luminescence (XEOL) together with X-ray absorption spectroscopy (XAS) measured both by total electron yield methods (TEY) and by using the optically detected photoluminescence yield method (PLY). XEOL spectra below K shell threshold show a broad emission peak at similar to 860 nm which can be attributed to the optical Q-band of these organic systems, which is then suppressed above the threshold. The shift to higher wavelength compared to optical emission spectra from MgPc in solution is consistent with intermolecular coupling of the excited states in the loosely intermolecular bonded phthalocyanine crystal structure. Zero order total PLY spectra at both C and N K edges are compared to TEY spectra where at the C K edge an inversion of intensity ratios between features is observed. Wavelength-specific PLY absorption spectra taken at 860 nm at the N K edge show a role for sigma* states participating in the luminescence process possibly through the sigma-like lone pair of bridging nitrogen atom, denoted the n -> pi* transition.

•Polyaniline/multi walled carbon nanotubes based hybrid webbed structures were electrodeposited on ITO substrates.•Tess on Enzyme based electrochemical detection of organophosphate pesticides in real samples.•Linear response with low detection limits in the concentration range of 10 ng/L to 120 ng/L was achieved. We report the development of an ultrasensitive electrochemical sensor using polyaniline (PANi) and carboxyl functionalized multi-walled carbon nanotubes (fMWCNT) for the detection of organophosphates (OPs) in real samples. The sensor was tested in the linear concentration range of 10 ng/L to 120 ng/L. The limit of detection (LoD) was found to be 8.8 ng/L with sensitivity 0.41 mA/ng/L/cm2 for chlorpyrifos (CPF); and 10.2 ng/L with sensitivity 0.58 mA/ng/L/cm2 for methyl parathion (MP). The vegetable samples (cucumber) were also tested. The average % recovery for CPF and MP were found to be 98.05% and 96.63% respectively. The developed sensor showed stability for a period of 30 days. The interference of the sensor was studied with heavy metals (cadmium (Cd), chromium (Cr), lead (Pb), arsenic (As)) which was found to be 

SFX-MeOTAD [2,2′,7,7′-tetrakis( N , N -di(4-methoxyphenyl)amino)-spiro-(fluorene-9,9′-xanthene)] (also known as X60) has emerged as a cost-effective alternative to the ubiquitous, but excessively-expensive, spiro-MeOTAD hole transport material (HTM) in perovskite solar cells. Using its pre-oxidised dicationic salt, SFX-(TFSI) 2 , a controlled concentration dependent conductivity tuning of this HTM without the requirement of air (oxygen) exposure has been carried out. This study details the modifications in the optical and electrical properties of this low cost HTM as a function of the concentration of the dicationic salt (0–100 mol%) using UV-vis absorption and electrical conductivity measurements. X-ray absorption and photoelectron spectroscopy investigations have been carried out to elucidate the role of the dicationic salt in the enhanced electronic properties of SFX-MeOTAD. By incorporating the dicationic SFX-(TFSI) 2 it has been shown that the conductivity of SFX-MeOTAD increased by 4 orders of magnitude from 2.55 × 10 −8 S cm −1 to 9.4 × 10 −4 S cm −1 when using an optimal dopant concentration of 20.5 mol%. The degree of oxidation of SFX-MeOTAD was determined through UV-vis absorption and consolidated using the computational calculations. The XPS study reveals that doping SFX-MeOTAD with SFX(TFSI) 2 not only results in the oxidation of the HTM but also leads to a variation in the local chemistry around carbon and nitrogen which directly influences the conductivity of the doped films. NEXAFS studies indicate that doping enhances the aromatic nature of the molecule initially but increasing the dopant concentration further affects the aromaticity and possibly the π stacking, similar to the trend seen in dopant concentration dependent conductivity of the SFX-MeOTAD films. These findings have implications on the choice of dopant concentration and counterions more generally for triarylamine based HTMs.

[Display omitted] •Outlines the most tunable and scalable fabrication techniques deciphering the characteristic properties affiliated with efficient light harvesting materials (LHM).•The incorporation of sequential harvesting complexes, or quantum dots with surficial absorption and excitation properties improve the future of LHM.•Fusing accelerometer technology and light harnessing, we might be able to feed the accelerated electrons to an energy harvesting system or the accelerated electrons.•Accelerated electrons can be used to irradiate DNA which has applications in ingestible batteries, as drug delivery vehicles and stimulants. In light of the ever growing enthusiasm and enormous curiosity towards bioinspired strategy of material fabrication, this review compiles the milestone in the world of bio-hybrid nanomaterials featured in light harvesting systems. The change in global climate emphasizes the need for alternative energy sources, so, comprehending the characteristic properties affiliated with nature sensitive light harvesting materials (LHM) along with their scalable fabrication techniques is a major research avenue. The last few decades have seen elevated efforts in understanding photosynthetic mechanisms, energy transfer, charge storage and principles of quantum coherence. These are further applied to devise synthetic alternatives for photo-electrochemical systems. The intriguing optoelectronic abilities of narrow bandgap semiconductors and self-assembly in bio-hybrid structures have been invasively studied to yield multifarious applications in, photocatalysis, as photoelectrodes, for hydrogen generation or water desalination. Translating the principles of evolution in natural photoactive complexes, material scientists have investigated new elements resulting in synergistic - biohybrid systems. The paper facilitates the reader with state-of-the-art examples offering a solid background to fuel innovations that can be shaped into real-world applications. From photosynthetic antennas, marine sea shells to tea leaf stains and DNA assembly, the platform has housed diverse sources converging on designing efficient and stable architectures. The article advances to modules classifying the origin of artificial optoelectronic alternatives and provides a garnered account of all addressed photo physical theories. The overview proposes the design of futuristic systems that utilize artificially intelligent energy harvesting schemes to build smart devices for biomedical and environmental remediation purposes. Hereby, we aim to provoke a cross-disciplinary discussion about the challenges and scope at the leading edge of this field and pitch to develop a different world through renewable energy push.

Recently, there have been enormous efforts to tailor the properties of graphene. These improved properties extend the prospect of graphene for a broad range of applications. Plasmas find applications in various fields including materials science and have been emerging in the field of nanotechnology. This review focuses on different plasma functionalization processes of graphene and its oxide counterpart. The review aims at the advantages of plasma functionalization over the conventional doping techniques. Selectivity and controllability of the plasma techniques opens up future pathways for large scale, rapid functionalization of graphene for advanced applications. We also emphasize on atmospheric pressure plasma jet as the future prospect of plasma based functionalization processes. Published by AIP Publishing.

Tailoring the surface properties by varying the chemistry and roughness could be of interest for self-cleaning applications. We demonstrate the transformation of hydrophobic ZnO Nano rod (NR) array into superhydrophobic nature by changing the local chemical state and without altering the surface roughness by swift heavy ion (SHI) irradiation. The aligned ZnO NR arrays were irradiated using 150 MeV Ag ions with different fluences from 5E10 to 3E12 ions/cm(2). The observed static water contact angles of ZnO NRs samples were 103 degrees +/- 3 degrees, 152 degrees +/- 4 degrees, 161 degrees +/- 3 degrees, 164 degrees +/- 2 degrees, 167 degrees +/- 2 degrees, 154 +/- 3 degrees and 151 degrees +/- 2 degrees for the pristine, ion fluencies of 1E11, 3E11, 5E11, 7E11, 1E12 and 3E12 ions cm(-2), respectively. The change in local surface chemistry via formation of surface oxygen related defects due to electronic excitations induced by ion irradiation determine the water dewetting properties. It is found that surface oxygen related defects could be tuned by varying the fluence of the SHIs. Durability tests show that the SHI induced surface oxygen-deficient ZnO NRs have the stable superhydrophobic behavior for more than a year.

Hollow onionlike carbon (OLC), generated by annealing nanodiamond at 2140 K, has been studied by core-level and valence-band photoemission spectroscopy. Upon intercalation with potassium, core and valence states of the OLC show an almost rigid shift to higher binding energies, and the density of states at the Fermi level (E-F) is observed to increase. An asymmetric broadening of the C1s line from the OLC as intercalation proceeds indicates an increase in electron-hole pair excitations. Both core and valence-band spectra are consistent with charge transfer from the intercalated potassium to the OLC, and support the conclusion that the electronic structure of the carbon onions bears strong similarity to that of graphite, although differences do exist. In consequence the conclusion can be drawn that these species behave as graphite "nanocrystals" rather than as large fullerene molecules.

Energy system modeling can be used to develop internally-consistent quantified scenarios. These provide key insights needed to mobilise finance, understand market development, infrastructure deployment and the associated role of institutions, and generally support improved policymaking. However, access to data is often a barrier to starting energy system modeling, especially in developing countries, thereby causing delays to decision making. Therefore, this article provides data that can be used to create a simple zero-order energy system model for a range of developing countries in Africa, East Asia, and South America, which can act as a starting point for further model development and scenario analysis. The data are collected entirely from publicly available and accessible sources, including the websites and databases of international organisations, journal articles, and existing modeling studies. This means that the datasets can be easily updated based on the latest available information or more detailed and accurate local data. As an example, these data were also used to calibrate a simple energy system model for Kenya using the Open Source Energy Modeling System (OSeMOSYS) and three stylized scenarios (Fossil Future, Least Cost and Net Zero by 2050) for 2020–2050. The assumptions used and the results of these scenarios are presented in the appendix as an illustrative example of what can be done with these data. This simple model can be adapted and further developed by in-country analysts and academics, providing a platform for future work.

The optical properties of four different silicon nanowire structures were investigated. Two of the samples consisted of spheres of nanocrystalline silicon en-capsulated by silicon oxide nanowires, with other two consisting of crystalline silicon nanowires coated by silicon oxide shells. The nanostructures produced by oxide assisted growth consisted of spheres of crystalline silicon encapsulated by silicon oxide shells. The absorption and photoluminescence of the different structures of the sample are investigated. The emitting species responsible for photoluminescence across the visible spectrum are discussed.

The persistent use of pesticides in the agriculture field remains a serious issue related to public health. In the present work, molecularly imprinted polymer thin films were developed using electropolymerization of pyrrole (py) onto gold microelectrodes followed by electrodeposition for the selective detection of chlorpyrifos (CPF). The molecularly imprinted polymer (MIP) was synthesized by the electrochemical deposition method, which allowed in-line transfer of MIP on gold microelectrodes without using any additional adhering agents. Various parameters such as pH, monomer ratio, scan rate, and deposition cycle were optimized for sensor fabrication. The sensor was characterized at every stage of fabrication using various spectroscopic, microscopic, and electrochemical techniques. The sensor requires only 2 mu L of the analyte and its linear detection range was found to be 1 mu M to 1 fM. The developed sensor's limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.93 and 2.82 fM, respectively, with a sensitivity of 3.98 (mu A/(mu M)/ mm(2). The sensor's shelf life was tested for 70 days. The applicability of the sensor in detecting CPF in fruit and vegetable samples was also assessed out with recovery % between 91 and 97% (RSD < 5%). The developed sensor possesses a huge commercial potential for on-field monitoring of pesticides.

In this work, we have prepared MoS2 nanoflakes modified TiO2 nanoparticles (MoS2-TiO2 nanocomposite) with varying concentration of MoS2 (2.5-10 wt.%) by a two-step hydrothermal synthesis method involving specific preparation conditions for the TiO2 nanoparticles and MoS2 nanoflakes. The prepared samples were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), and X-ray photoelectron spectroscopy (XPS) techniques. The photocatalytic activity of the pristine TiO2 nanoparticles and MoS2-TiO2 nanocomposite samples were evaluated by examining the photocatalytic degradation of Rhodamine B (RhB). The photoelectrochemical activity of these samples were measured by performing solar water splitting experiments under visible light irradiation. It was observed that the MoS2-TiO2 nanocomposite with 7.5 wt.% MoS2 exhibits highest photo catalytic and photoelectrochemical activity as it has the optimum amount of MoS2 nanoflakes which probably minimizes the recombination of photogenerated charge carriers as compared to other concentrations of MoS2 in MoS2-TiO2 nanocomposite and pristine TiO2 nanoparticles. In addition, a rather high photocatalytic reaction rate constant was observed for MoS2-TiO2 nanocomposite with 7.5 wt.% MoS2 nanoflakes.

The ubiquitous manufacturing of lithium-ion batteries(LIBs) dueto high consumer demand produces inevitable e-waste that imposes severeenvironmental and resource sustainability challenges. In this work,the charge storage capability and Li-ion kinetics of the recoveredwater-leached graphite (WG) anode from spent LIBs are enhanced byusing an optimized amount of recycled graphene nanoflakes (GNFs) asan additive. The WG@GNF anode exhibits an initial discharge capacityof 400 mAh g(-1) at 0.5C with 88.5% capacity retentionover 300 cycles. Besides, it delivers an average discharge capacityof 320 mAh g(-1) at 500 mA g(-1) over 1000cycles, which is 1.5-2 times higher than that of WG. The sharpincrease in electrochemical performance is due to the synergisticeffects of Li-ion intercalation into the graphite layers and Li-ionadsorption into the surface functionalities of GNF. Density functionaltheory calculations reveal the role of functionalization behind thesuperior voltage profile of WG@GNF. Besides, the unique morphologyof spherical graphite particles trapping into graphene nanoflakesprovides mechanical stability over long-term cycling. This work explainsan efficient strategy to upgrade the electrochemical compatibilityof recovered graphite anode from spent LIBs toward next-generationhigh-energy-density LIBs.

Integration of nanotechnology and advanced manufacturing processes presents an attractive route to produce devices for adaptive biomedical device technologies. However, tailoring biological, physical, and chemical properties often leads to complex processing steps and therefore to high manufacturing cost impeding further scalability. Herein, a novel laser-based approach is introduced to manufacture low cost biocompatible polymer substrates functionalized with ultrapure nanoparticles. Laser direct writing was performed to create micron-sized patterns on 188 μm-thick cyclic olefin polymer (COP) substrates using a picosecond pulsed 1064 nm Nd:YAG laser. The Pulsed Laser Ablation in Liquids (PLAL) technique was exploited in this work to prepare colloidal solutions of ultrapure nanoparticles to impart bio-functionality onto laser patterned surfaces. Combining the laser patterns and their modification with PLAL-nanoparticles resulted in a functional and biocompatible substrate for biosensing applications. Our in vitro cell viability studies using a model cell line (human skin keratinocyte, HaCaT) suggest that these nanoparticles immobilized on the surfaces function as a biomimetic platform with the ability to interact with different biological entities ( e.g. DNA, antibodies etc. ).

[Display omitted] •Growth of TiO2 thin films with in-situ plasma hydrogenation.•Presence of Ti2+ states in addition to Ti3+ states present in pristine TiO2.•Change in VBM, work function and band gap in iH:TiO2.•Enhanced photocurrent density as compared to pristine TiO2 films. In this paper, we report the effect of in-situ plasma hydrogenation of TiO2 (iH:TiO2) thin films by the incorporation of known amount of hydrogen in the Ar plasma during rf-sputter deposition of TiO2 films. As compared to pristine TiO2 films (∼0.43mA/cm2 at 0.23V vs Ag/AgCl), hydrogenated TiO2 showed enhanced photoelectrochemical activity in terms of improved photocurrent density of ∼1.08mA/cm2 (at 0.23V vs Ag/AgCl). These results are explained in terms of reduction in band gap energy, shift in valence band maximum away from the Fermi level, improved donor density and more negative flat band potential in iH:TiO2 sample. The presence of Ti2+ states in iH:TiO2 films in addition to Ti3+ states in pristine TiO2 act as additional electronic states in the TiO2 band gap and increases the optical absorption in the visible region. This method of in-situ hydrogenation can be used as a general method for improving the properties of metal oxide thin films for photoelectrochemical and photocatalytic applications.

► Thin ZnO films and high quality ZnO crystal were electrochemically doped with hydrogen. ► Hydrogen absorbed in ZnO causes plastic deformation both in ZnO crystal and thin films. ► In ZnO crystal a sub-surface region with very high density of defects was formed. ► Moreover, plastic deformation causes specific surface modification of ZnO crystal. ► In ZnO films hydrogen-induced plastic deformation introduced defects in the whole film. ZnO films with thickness of ∼80nm were grown by pulsed laser deposition (PLD) on MgO (100) single crystal and amorphous fused silica (FS) substrates. Structural studies of ZnO films and a high quality reference ZnO single crystal were performed by slow positron implantation spectroscopy (SPIS). It was found that ZnO films exhibit significantly higher density of defects than the reference ZnO crystal. Moreover, the ZnO film deposited on MgO substrate exhibits higher concentration of defects than the film deposited on amorphous FS substrate most probably due to a dense network of misfit dislocations. The ZnO films and the reference ZnO crystal were subsequently loaded with hydrogen by electrochemical cathodic charging. SPIS characterizations revealed that absorbed hydrogen introduces new defects into ZnO.

Ultrathin conductive carbon layers (UCCLs) were created by spin coating resists and subsequently converting them to conductive films by pyrolysis. Homogeneous layers as thin as 3 nm with nearly atomically smooth surfaces could be obtained. Layer characterization was carried out with the help of atomic force microscopy, profilometry, four-point probe measurements, Raman spectroscopy and ultraviolet–visible spectroscopy. The Raman spectra and high-resolution transmission electron microscopy image indicated that a glassy carbon like material was obtained after pyrolysis. The electrical properties of the UCCL could be controlled over a wide range by varying the pyrolysis temperature. Variation in transmittance with conductivity was investigated for applications as transparent conducting films. It was observed that the layers are continuous down to a thickness below 10 nm, with conductivities of 1.6 × 10 4 S/m, matching the best values observed for pyrolyzed carbon films. Further, the chemical stability of the films and their utilization as transparent electrochemical electrodes has been investigated using cyclic voltammetry and electrochemical impedance spectroscopy.

The toxic nature of inorganic nanostructured materialsas photocatalystsis often not accounted for in traditional wastewater treatment reactions.Particularly, some inorganic nanomaterials employed as photocatalystsmay release secondary pollutants in the form of ionic species thatleach out due to photocorrosion. In this context, this work is a proof-of-conceptstudy for exploring the environmental toxicity effect of extremelysmall-sized nanoparticles (

A technique to increase the conductivity of Spiro-OMeTAD using an easily scalable, non-thermal atmospheric pressure plasma jet (APPJ) is reported. An investigation of plasma functionalization demonstrated an enhancement in hole conductivity by over an order of magnitude from 9.4 × 10−7 S cm−1 for the pristine film to 1.15 × 10−5 S cm−1 for films after 5 minutes of plasma treatment. The conductivity value after plasma functionalization was comparable to that reported for 10–25% Li-TFSI-doped Spiro-OMeTAD. The increase in conductivity was correlated with a reduction in phase value observed using electrostatic force microscopy. Kelvin probe force microscopy showed an increase in work function after plasma exposure corresponding to the p-type nature of the doping. X-ray photoelectron spectroscopy revealed surface oxidation of plasma-functionalized films, as well as variation in nitrogen chemistry, with the formation of a higher binding energy quaternary nitrogen tail. Oxidation of Spiro-OMeTAD was also confirmed by the appearance of the 500 nm absorption peak using UV–vis spectroscopy. The synergistic contribution of increase in charge density in Spiro-OMeTAD due to the energetic species in the plasma jet coupled with improvement in π-π stacking of the molecules is thought to underlie the conductivity enhancement. The enhancement in positive charges can also be attributed to the formation of quinoid structures with quaternary nitrogen +N=C formed due to loss of methyl groups during plasma surface interaction. This work opens up the possibility of using an atmospheric pressure plasma jet as a simple and effective technique for doping and functionalizing Spiro-OMeTAD thin films to circumvent the detrimental issues associated with chemical dopants. [Display omitted] •A non-thermal atmospheric pressure plasma jet was used to functionalize and oxidise Spiro-OMeTAD films.•The hole conductivity is increased by more than one order of magnitude after 5 minutes of plasma treatment, reaching 10−5 S cm−1.•Increase in charge density in Spiro-OMeTAD due to the energetic species in the plasma jet.•Improvement in π-π stacking of the molecules enhances the conductivity.•Work function increases with plasma-functionalized Spiro-OMeTAD justifying p-type dopant.

The morphology and surface characteristics of SCS (Solution Combustion Synthesis)-derived Ni-NiO nanocatalysts were studied. The Tau Epsilon Mu results highlighted that the nanomaterial's microstructure was modified by changing the reactants' concentrations. The dendrites' growth conditions were the main factors responsible for the observed changes in the nanomaterials' crystallite size. Infrared camera measurements demonstrated a new type of combustion through dendrites. The XPS analysis revealed that the NiO structure resulted in the bridging of the oxygen structure that acted as an inhibitor of hydrogen adsorption on the catalytic surface and, consequently, the activity reduction. The RF-IGC indicated three different kinds of active sites with different energies of adsorption on the fresh catalyst and only one type on the aged catalyst. Aging of the nanomaterial was associated with changes in the microstructure of its surface by a gradual change in the chemical composition of the active centers.

In this work, we demonstrate doping graphene oxide (GO) films using a low power atmospheric pressure plasma jet (APPJ) with subsequent tuning of the work function. The surface potential of the plasma functionalized GO films could be tuned by 120 ± 10 mV by varying plasma parameters. X-ray spectroscopy used to probe these changes in electronic structure of systematically functionalized GO films by plasma. Detailed investigation using X-ray photoelectron spectroscopy and near edge X-ray absorption fine structure spectroscopy revealed the reactive nitrogen species in the plasma induce finite changes in the surface chemistry of the GO films, introducing additional density of states near the top of the valence band edge. Nitrogen introduced by the atmospheric pressure plasma is predominantly in a graphitic configuration with a varying concentration of pyridinic nitrogen. Additionally, evidence of gradual de-epoxidation of these GO films with increasing plasma exposure was also observed. We attribute this variation in work function values to the configuration of nitrogen in the graphitic structure as revealed by X-ray spectroscopy. With pyridinic nitrogen the electronic states of GO became electron deficient, inducing a p-type doping whereas an increase in graphitic nitrogen increased the electron density of GO leading to an n-type doping effect. Nitrogen doping was also found to decrease the resistivity from 138 MΩ sq −1 to 4 MΩ sq −1 . These findings are extremely useful in fabricating heterojunction devices like sensors and optoelectronic devices where band structure alignment is key to device performance when GO is used as a charge transport layer. This technique can be extended to other known 2D systems.

Graphite is an integral part of lithium-ion batteries (LIBs). However, due to limited resources and high production cost, producing battery grade graphite to meet the increasing demands for energy storage devices is becoming a challenge. One viable approach is to recycle the spent graphite anodes from end-of-life LIBs. Importantly, recycling of spent lithium-ion batteries (LIBs) is off utmost importance to address the global challenge of electronic waste management. Herein, we present an environmentally friendly technique of graphite recycling from spent LIB by water leaching, followed by atmospheric plasma jet printing. The major advantage of this method is that it does not require any binders or conductive diluents. Plasma-printed recycled graphite showed a significantly enhanced specific capacity of 402 mAh g−1 at 500 mA g−1 at the end of the 1000th charge-discharge cycle, in comparison to water-washed recycled graphite (112 mAh g−1) and a 23.35 times faster diffusivity of Li+. A detailed experimental investigation revealed that the plasma activation of the graphitic structure resulted in the improved reversible Li+ storage. This work provides a new perspective on the recycling strategy of graphite anodes using in situ plasma functionalization, a significant step towards the sustainable future of LIBs. Here, we demonstrate an eco-friendly method to recycle graphite from spent Lithium-ion batteries (LIBs). High-capacity anodes are prepared by plasma jet printing of extracted graphite without the use of conventional additives. This study paves the way towards sustainable recycling of spent LIB anodes to be reused as high-performance anode material for LIBs using plasma printing technology. [Display omitted]

The use of pesticides in agriculture field remains a serious issue related to public health. This necessitates the need to develop a low cost/portable, sensitive and selective bio-sensing platform for detection of pesticides in food chain. In this work a low-cost biosensing platform for ultrasensitive detection of chlorpyrifos (CPF) is developed. Electrochemical micro Paper Analytical Device ( \text{E}\mu PAD) is fabricated by conventional screen-printing technology. Metal Organic Framework (Z1200 MOF) having zinc metal and imidazole ligand is used as a transducing element which facilitates biocompatible matrix for Acetylcholinesterase (AChE) enzyme immobilization. The limit of detection for CPF is found be 3 ng/L with sensitivity 0.521 \text{k}\Omega /ng \text{L}^{-1} /mm ^{2} . The sensor required 100\mu \text{L} of reagent and was tested with a linear concentration range of 10 ng/L to 1000 ng/L with response time of 5s. The sensor is further integrated with portable electronics based on Arduino microcontroller and Artificial Intelligence (AI) which provided economical, portable and user-friendly sensing platform. The stability of the sensor was 30 days. The developed sensor was also tested with real samples and the sensor response is in agreement with conventional technique.

The formation of surface nitrides on gold films is a particularly attractive proposition, addressing the need to produce harder, but still conductive, gold coatings which reduce wear but avoid the pollution associated with conventional additives. Here we report production of large area gold nitride films on silicon substrates, using reactive ion sputtering and plasma etching, without the need for ultrahigh vacuum. Nanoindentation data show that gold nitride films have a hardness ∼ 50 % greater than that of pure gold. These results are important for large-scale applications of gold nitride in coatings and electronics.

Over the last decade the progress in amorphous and nanocrystalline silicon (nc-Si) for photovoltaic applications received significant interest in science and technology.Advances in the understanding of these novel materials and their properties are growing rapidly. In order to realise nc-Si in the solar cell, a thicker intrinsic layer is required. Due to the indirect band gap in the crystallites, the absorption coefficients of nc-Si are much lower. In this work we have used electrochemical etching techniques to produce silicon nanocrystals of the sizes 3–5 nm. Viable drop cast deposition of Si nanocrystals to increase the thickness without compromising the material properties was investigated by atomic force microscopy, optical microscopy, photoemission spectroscopy and optical absorption methods.

[Display omitted] •Correlations of two simultaneous as well as significant observations coming out from a single composite (CNT/ZnO) for the detection of VOCs.•A unique adsorption switching followed by p- to n- transition is observed in VOC detection.•The high reproducible sensors are selective towards methanol (R∼73 ± 3 %) and 8-fold enhancement in response compared to ethanol.•Composite sensor working looks like a full wave rectification process. The present study correlates two simultaneous as well as significant observations coming out from a single sensing prototype concerning the detection of volatile organic compounds (VOCs) by a carbonaceous material based sensor. We have developed a composite based chemiresistive sensor utilizing two different components (carbon nanotube (CNT) and zinc oxide (ZnO)). This is reflected in a unique adsorption switching phenomena followed by a ‘p- to n-’ type transition characteristics above a certain operating temperature (150 °C) in the VOC detection process. Noticeably, by the virtue of adsorption switching, the CNT/ZnO composite is able to operate as a dual mode sensor, in which CNT dominates in low temperature region (≤ 150 °C) and ZnO at high temperature region (>150 °C) with a realistic detection ability. The highly reproducible sensors (29 prototypes) are selective towards methanol (Response, R ∼ 73 ± 3 %) and shows 8-fold enhancement in response value compared to neighbouring VOC i.e., ethanol at an operating temperature of 150 °C with a very low bias voltage of 10 mV. Finally, the adsorption switching phenomena (physisorption to chemisorption) has been explained by Fourier Transform Infrared Spectroscopy (FTIR) study and activation energy values along with ‘p- to n-’ type transition is compared qualitatively with a typical full wave rectification process.

Fully exploiting the properties of graphene will require a method for the mass production of this remarkable material. Two main routes are possible: large-scale growth or large-scale exfoliation. Here, we demonstrate graphene dispersions with concentrations up to similar to 0.01 mg ml(-1), produced by dispersion and exfoliation of graphite in organic solvents such as N-methyl-pyrrolidone. This is possible because the energy required to exfoliate graphene is balanced by the solvent-graphene interaction for solvents whose surface energies match that of graphene. We confirm the presence of individual graphene sheets by Raman spectroscopy, transmission electron microscopy and electron diffraction. Our method results in a monolayer yield of similar to 1 wt%, which could potentially be improved to 7-12 wt% with further processing. The absence of defects or oxides is confirmed by X-ray photoelectron, infrared and Raman spectroscopies. We are able to produce semi-transparent conducting films and conducting composites. Solution processing of graphene opens up a range of potential large-area applications, from device and sensor fabrication to liquid-phase chemistry.

Here we report a novel hydrothermal method to synthesize hybrid nanostructures based on single phase cobalt disulfide (CoS2) nanoparticles decorated on multiwalled carbon nanotubes (MWCNT) for application as supercapacitor electrode. This is also the first report on systematic investigation of the influence of MWCNTs on the electrochemical properties of CoS2 nanoparticle based electrode for supercapacitor. The X-ray diffraction and electron microscopic analyses revealed that incorporation of CNTs promotes the growth of only the CoS2 phase in the form of spherical nanoparticles with an average diameter of similar to 9 nm. CoS2-MWCNT nanohybrid electrode containing 20 wt % MWCNT showed the highest specific capacitance of 1486 F/g at 1 A/g discharge current density along with excellent reversibility. It also showed high cycle stability with similar to 80% retention of specific capacitance even after 10,000 cycles. Thus, we show a low cost and simple method to synthesize a CoS2-MWCNT nanohybrid that has great promise as electrode material for supercapacitor applications. Incorporation of CNT not only provides a conducting network for fast charge diffusion but (due to large surface area) also allows more CoS2 molecules to be readily available for redox reaction resulting in the reduction of the charge transfer resistance consistent with the data obtained from electrochemical impedance spectroscopy.

An Electrochemical micro Analytical Device (EµAD) was fabricated for sensitive detection of organophosphate pesticide chlorpyrifos in the food chain. Gold microelectrode (µE) modified with Zinc based Metal Organic Framework (MOF-Basolite Z1200) and Acetylcholinesterase (AChE) enzyme served as an excellent electro-analytical transducer for the detection of chlorpyrifos. Electrochemical techniques such as Cyclic Voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS) and Differential Pulse Voltammetry (DPV) were performed for electrochemical analysis of the developed EµAD. The sensor needs only 2 µL of the analyte and it was tested within the linear range of 10 to 100 ng/L. The developed EµAD's limit of detection (LoD) and sensitivity is 6 ng/L and 0.598 µ A/ng L /mm respectively. The applicability of the device for the detection of chlorpyrifos from the real vegetable sample was also tested within the range specified. The fabricated sensor showed good stability with a shelf-life of 20 days. The EµAD's response time is of 50 s, including an incubation time of 20 s. The developed EµAD was also integrated with commercially available low-cost, handheld potentiostat (k-Stat) using Bluetooth and the results were comparable with a standard electrochemical workstation.

A process was developed to disperse beta-SiC nancparticies (NPs), with a high propensity to agglomerate, within a matrix of A356 aluminum alloy. A suitable dispersion of 1 wt% SiC NPs in the A356 matrix was obtained through a hybrid process including a solid-state modification on the surface of the NPs, a two-step stirring process in the semi-solid and then the liquid-state, and a final hot-rolling process for fragmentation of the brittle eutectic silicon phase and porosity elimination. Titanium and nickel where used as the nanoparticle SiC surface modifiers. Both modifiers were found to improve the mechanical properties of the resulting material, however, the highest improvement was found from the nickel surface modification. For the nickel modification, compared to the non-reinforced rolled alloy, more than a 77%, 85%, and 70% increase in ultimate tensile strength (UTS), yield strength (YS), and strain % at the break, respectively were found with respect to the unreinforced rolled A356. For the rolled nanocomposite containing 1 wt % SiCnp and nickel modification, an average YS, UTS, and strain % at the break of 277 MPa, 380 MPa, and 16.4% were obtained, respectively, which are unique and considerable property improvements for A356 alloy.

We report systematic investigations on structural, magnetic and optical properties of NiO nanoparticles prepared by mechanical alloying. As-milled powders exhibit face centred cubic structure, but average particle size decreases and effective strain increases for the initial periods of milling. Lattice volume increases monotonically with a reduction in particle size. Antiferromagnetic NiO particles exhibit significant room temperature (RT) ferromagnetism with modest moment and coercivity. A maximum moment of 0.0147 mu(B)/f.u at 12 kOe applied field and a coercivity of 160 Oe were obtained for 30 h milled NiO powder. Exchange bias decreases linearly with a decrease in NiO particle size. Thermo-magnetization data reveal the presence of mixed magnetic phases in milled powders and shifts magnetic phase transition towards high temperature with increasing milling. Annealing of milled NiO powder and photoluminescence studies show a large reduction in RT magnetic moment and blue-shifting of band edge emission peak. The observed properties are discussed on the basis of finite size effect, defect density, oxidation/reduction of Ni, increase in number of sublattices, uncompensated spins from surface to particle core, and interaction between uncompensated surfaces and particle core with lattice expansion.

[Display omitted] •Usage of cellulose biomass-based hydrogel towards water pollutants are discussed.•The present state of preparation of cellulose derived composites is summarized.•Progress and future directions are discussed. Despite several technological improvements and achievements, wastewater treatment remains a serious issue internationally. Toxins in wastewater pose a significant threat to human health if left untreated. Due to macro-porous structure and different surface functionalization, cellulose biomass-based hydrogel is the most traditional adsorbent for removing harmful ions from wastewater. Recently, the introduction of several new cellulose derived materials have demonstrated their competitiveness in the removal of harmful ions. Numerous exceptional qualities better define this promising material, including high mechanical strength, large surface area and chemical inertness. This paper discusses the development status, preparation and modification methods of cellulose composites created by various materials (graphene, fly ash, graphene oxide and bentonite) which evaluates the research development and existing challenges in water treatment.

Two-dimensional (2D) Molybdenum disulfide (MoS2) has become one of the most exciting areas of research for adsorbents due to its high surface area and abundant active sites. Mainly, 2D MoS2 show promising removal of textile dye pollutants by adsorption process, but it show high affinity for anionic type of dyes, that limits its performance in mixed dye pollutants treatment. Herein, we demonstrate an integrated approach to remove mixed dye pollutants (anionic and cationic) concurrently by combining adsorption and photocatalysis process. We synthesize MoS2/TiO2 nanocomposites for different weight percentages 2.5, 5, 10, 20, 30 and 50 wt% of pre-synthesized flower-like MoS2 nanoparticle by a two-step hydrothermal method. We demonstrate a new process of two-stage adsorption/photocatalysis using high wt% of MoS2 (Stage-I) and low wt% of MoS2 (Stage-II) nanocomposites. The proposed two-stage integrated adsorption and photocatalysis process using 50% and 2.5% of MoS2 coated TiO2, respectively showed complete removal of methylene blue dye ∼5 times faster than conventional single-stage (adsorption or photocatalysis) water treatment process. Furthermore, the feasibility of the proposed two-stage method in mixed dye pollutants removal (anionic and cationic) testified, which showed excellent performance even in doubling the dye pollutant concentration. This work brings a deeper insight into understanding the morphology and concentration of 2-D MoS2 in MoS2/TiO2 nanocomposite in tackling mixed dye pollutants and the possibilities of applying in textile dyeing industries wastewater treatment plants. [Display omitted] •2-D MoS2/TiO2 composite synthesized for different weight % of MoS2.•Hybrid adsorption-photocatalysis route showed a high rate of dye pollutants removal.•2-D MoS2 layer lattice widening play a key role in dye pollutants removal.•Anionic and cationic mixed dye pollutants removed simultaneously.•Two-stage process results 5 times faster dye removal rate than conventional route.

The instability in aqueous solutionshas impeded the effectiveemployment of metal-organic frameworks (MOFs) for various photocatalyticapplications. Recent literatures have proven that certain supportslike graphitic carbon nitride (g-C3N4) can improvethe water stability and meet other functionalities responsible forphotocatalytic water splitting. To expound on the mechanistic detailscentral to the photoactivity of g-C3N4/MOF systems,we relate the activity of an amorphous nickel imidazole framework(aNi-MOF) with different vacancy (carbon and nitrogen) defects ofengineered g-C3N4 systems. Vacancy defects significantlyalter the electronic structure and characteristics of photoexcitedcharge carriers and thus the photocatalytic activity of semiconductorphotocatalysts. In this framework, by elucidation of both experimentaland theoretical studies, carbon-defective g-C3N4 with aNi-MOF (CvCN/aNi) proves to be a potential candidateto speed up the photocatalytic hydrogen evolution reaction. The resultsalso potentially accord to the reactive interaction between g-C3N4 and aNi-MOF that a Ni-N bond is vitalin the photoactivity with the carbon-defective CvCN/aNiphotocatalyst producing 3922.01 mu mol g(-1) for3 h, which is 3900 and 1700 times better than those of pristine aNi-MOFand g-C3N4, respectively. Our report providesinsight into correlating the reactive mechanism in a g-C3N4/MOF system and the role of defects in photocatalytichydrogen evolution reactions.

Thin films of Cu2ZnSnS4 (CZTS) were synthesized via a low cost, wet chemical technique of chemical bath deposition (CBD). In the first part of this study, the chemical composition ratio S/(Cu+Zn+Sn) was varied keeping Cu/(Zn + Sn) and Zn/Sn ratios constant to study the effect of sulfur variation. Detailed electrical and optical characterization has been carried out using UV-visible spectroscopy, x-ray diffraction, x-ray photoelectron spectroscopy, Raman spectroscopy and Kelvin probe force microscopy (KPFM) techniques. The results of the present study confirm that near ideal stoichiometry could be achieved in CZTS by adding excess thiourea in a controlled manner which eliminated the need for an additional step of sulfurization. Using the stoichiometric sample as the basis, in the second part of the study Cu/(Zn+Sn) and Zn/Sn was varied and it was found that the electronic properties of CZTS in terms of band gap, work function and valence band edge position could be controlled by precursor variation. KPFM was used to qualitatively evaluate the photoresponse of the films and the Cu-poor, Zn-rich samples showed the best photoresponse out of all the samples which has been attributed to a decrease in the CuZn type defects. The study thus demonstrates a scalable and low-cost technique to grow CZTS absorber layers for solar cells with control over its electronic properties which is important for effective device operation. •Stoichiometric CZTS films have been synthesized by a low cost, wet chemical method.•The films do not require post-synthesis high temperature sulfurization.•Band structure of the material has been controlled by precursor variation.•KPFM has been used to qualitatively evaluate photoresponse of films.•Improved photoresponse attributed to decrease in CuZn type antisite defects.

Photoelectron spectroscopy has been used to study the products resulting from high temperature phase transformation of nanodiamonds (ND). Depending on the temperature of annealing various particles with a diamond core covered by nanometer sized fullerene-like shells, and onionlike carbon (OLC) were formed. Analysis of the C1s photoemission lines of the intermediates of ND transformation, prepared at temperatures of 1420 and 1600 K and then exposed to atmosphere, reveals the presence of oxygen-containing groups and both sp2 and sp3 carbon. The sp2 component for these samples has binding energies of 284.70±0.05 eV (for the sample prepared at 1420 K) and 284.50±0.05 eV (for the sample prepared at 1600 K). A difference of 1.3±0.1 eV in the binding energy of the sp3 and sp2 components was observed. The sp2 component for OLC prepared at 1800, 1900, and 2140 K has a binding energy of 284.45±0.05 eV. The shift towards higher binding energies of the sp2 component of the samples prepared at lower temperatures is explained by significant curvature of graphite layers formed in the initial stages of graphitization. The observed increase in density of states at the Fermi level for the samples prepared at 1600, 1800, and 1900 K is associated with an accumulation of different types of defects in the curved graphite layers during graphitization of diamond. The Lorentzian widths of C1s photoemission lines from OLC are large compared with those of HOPG. The possible reasons for this broadening are discussed.

Herein, we report a simple hydrothermal method to synthesize CeO2/Ce2O3 quantum dots anchored on reduced graphene oxide (RGO) sheets of different weight fractions for application as supercapacitor electrode. Of all the tested samples, the one containing 7 wt% RGO (CRGO3) as measured by thermogravimetry, exhibited the highest specific capacitance of 1027 F/g at 1 A/g along with good cycling stability. At current density of 4 A/g, the CRGO3 sample showed charge retention of 79% after 5000 cycles, whereas at 20 A/g, it showed 85% charge retention after 3000 cycles. The values obtained for CRGO3 electrode are better than all previous ceria and RGO based electrode suggesting its potential use in supercapacitor. High resolution transmission electron microscopy (HRTEM) revealed well crystalline CeO2 nanoparticles (similar to 5 nm) uniformly distributed on the RGO sheets as well as few lattice planes indicative of presence of some Ce2O3 mixed with CeO2. X-ray photoelectron spectroscopy (XPS) revealed presence of a mixed oxides containing mostly CeO2 with some Ce2O3 phase on the surface. The enhanced performance of the CRGO3 electrode was attributed to the optimized weight fraction and large surface area of electrically conducting RGO combined with enhanced electrocatalytic activity of CeO2/Ce2O3 mixed oxides.

Epitaxial growth of CuO nanostructures on Cu2O films using atmospheric pressure plasma jet is demonstrated, that can operate without the need of transparent current collector. [Display omitted] •Fast and environment friendly route for CuO/Cu2O heterojunction synthesis.•Epitaxial growth using atmospheric pressure plasma jet.•The heterojunction electrodes can operate without transparent current collector.•High currents and stability towards electrocatalysis and photocatalysis. A novel route to fabricate Cu2O/CuO heterojunction electrodes using an atmospheric pressure plasma jet (APPJ) is demonstrated. This process promotes favourable band alignment and produces nanoscale CuO surface features from Cu2O with low density of interfacial defects. This electrode can operate without any transparent current collector, showing remarkable currents and stability towards oxygen evolution reaction (OER) (6 mA cm−2 for 2 h at pH14) as well as photocatalytic hydrogen evolution reaction (HER) activity (−1.9 mA cm−2 for 800 s at pH7). When the electrocatalytic oxygen evolution (OER) activity was measured for Cu2O/CuO electrode deposited on FTO substrate the currents increased to ~40 mA cm−2 at 0.8 V vs SCE in 1 M KOH without compensating for the electrode electrolyte surface resistance (iR correction). The composite films also exhibited a high rate towards photo degradation of Methylene Blue (MB) and phenol in the visible spectra, indicating efficient charge separation. We modelled the electronic structure of this epitaxially grown Cu2O/CuO heterojunction using density functional theory. The calculations revealed the distinctive shifts towards Fermi level of the p-band centre of O atom in Cu2O and d-band centre of Cu atom in CuO at the interface contribute towards the increased catalytic activity of the heterostructure. Another factor influencing the activity stems from the high density of excited species in the plasma introducing polar radicals at the electrode surface increasing the electrolyte coverage. This work presents the potential of APPJ functionalization to tune the surface electronic properties of copper oxide based catalysts for enhanced efficiency in OER and HER water splitting.

ZnO thin films were grown by pulsed laser deposition on three different substrates: sapphire (0 0 0 1), MgO (1 0 0) and fused silica (FS). The structure and morphology of the films were characterized by x-ray diffraction and scanning electron microscopy and defect studies were carried out using slow positron implantation spectroscopy (SPIS). Films deposited on all substrates studied in this work exhibit the wurtzite ZnO structure and are characterized by an average crystallite size of 20-100 nm. However, strong differences in the microstructure of films deposited on various substrates were found. The ZnO films deposited on MgO and sapphire single-crystalline substrates exhibit local epitaxy, i.e. a well-defined relation between film crystallites and the substrate. Domains with different orientation relationships with the substrate were found in both films. On the other hand, the film deposited on the FS substrate exhibits fibre texture with random lateral orientation of crystallites. Extremely high compressive in-plane stress of sigma similar to 14 GPa was determined in the film deposited on the MgO substrate, while the film deposited on sapphire is virtually stress-free, and the film deposited on the FS substrate exhibits a tensile in-plane stress of sigma similar to 0.9 GPa. SPIS investigations revealed that the concentration of open-volume defects in the ZnO films is substantially higher than that in a bulk ZnO single crystal. Moreover, the ZnO films deposited on MgO and sapphire single-crystalline substrates exhibit a significantly higher density of defects than the film deposited on the amorphous FS substrate.

Electron transfer mechanisms in Shewanella loihica PV-4 viable biofilms formed at graphite electrodes were investigated in potentiostat-controlled electrochemical cells poised at oxidative potentials (0.2V vs. Ag/AgCl). Chronoamperometry (CA) showed a repeatable biofilm growth of S. loihica PV-4 on graphite electrode. CA, cyclic voltammetry (CV) and its first derivative shows that both direct electron transfer (DET) mediated electron transfer (MET) mechanism contributes to the overall anodic (oxidation) current. The maximum anodic current density recorded on graphite was 90μAcm−2. Fluorescence emission spectra shows increased concentration of quinone derivatives and riboflavin in the cell-free supernatant as the biofilm grows. Differential pulse voltammetry (DPV) show accumulation of riboflavin at the graphite interface, with the increase in incubation period. This is the first study to observe a gradual shift from DET to MET mechanism in viable S. loihica PV-4 biofilms. ► S. loihica PV- 4 forms uniform 2-3 µm thick biofilms on graphite electrode. ► Flavins accumulate at the interface S. loihica PV- 4 biofilm/graphite electrode. ► DET shift towards MET mechanism as S. loihica PV-4 biofilm grew on graphite.

We report the growth of carbon nanotubes on the size controlled iron catalytic nanoparticles. The nanotubes were grown by thermal chemical vapour deposition (CVD) in the temperature range 600-850 degrees C. The Fe films were deposited on silicon by pulsed laser deposition in vacuum. Atomic force microscopy measurements were performed on the catalytic nanoparticles. The topography of the catalytic nanoparticles shows the homogenous distribution of Fe catalyst. We observe the nanotubes are produced only at temperatures between 650 and 800 degrees C, and within this narrow temperature regime the yield of nanotubes reaches a maximum around 750 degrees C and then declines. Raman measurements illustrate a high G/D peak ratio indicating good nanotube quality. By further defining the size of the catalyst the diameter of these carbon nanotubes can be controlled.

Abstract From the environmental perspective, efficient plastic utilization and its recyclability become significant issues that need to be resolved for deploying urban and sustainable technologies. It is estimated that approximately 400 million tons of plastic are produced each year for different applications. This number will be doubled by 2050, which is a serious problem. The primary issue that arises in a recycling process is associated with optimum supply chain management. The comprehensive and transparent supply chain methodologies will help stockholders to make conclusive policies and precise strategies. Transparency in supply chain management assists in captivating planning, pricing, purchasing, and inventory management decisions. Environmental sustainability requires recycling, which should have innovative concepts like Artificial Intelligence (AI) and Block‐chain Technology. Manual methods of sorting and segregating the waste have outdated and not much efficient. The inclusion of AI and Blockchain Technology brought a revolution by increasing the efficiency and accuracy of the recycling process. This critical review focused on recycling plastics and plastic waste using AI and Blockchain Technology. Various plastic regulation policies and AI utilization for plastic recycling are discussed. An overview of the blockchain and its classification for waste management or plastic recycling has been discussed. The utilization of Blockchain Technology for a plastic circular economy, its types, and critical benefits has also been systematically demonstrated.

The real-time textile dyes wastewater contains hazardous and recalcitrant chemicals that are difficult to degrade by conventional methods. Such pollutants, when released without proper treatment into the environment, impact water quality and usage. Hence, the textile dye effluent is considered a severe environmental pollutant. It contains mixed contaminants like dyes, sodium bicarbonate, acetic acid. The physico-chemical treatment of these wastewaters produces a large amount of sludge and costly. Acceptance of technology by the industry mandates that it should be efficient, cost-effective and the treated water is safe for reuse. A sequential anaerobic-aerobic plant-microbe system with acclimatized microorganisms and vetiver plants, was evaluated at a pilot-scale on-site. At the end of the sequential process, decolorization and total aromatic amine (TAA) removal were 78.8% and 69.2% respectively. Analysis of the treated water at various stages using Fourier Transform Infrared (FTIR), High Performance Liquid Chromatography (HPLC)) Gas Chromatography-Mass Spectrometry (GC-MS) Liquid Chromatography-Mass Spectrometry (LC-MS) indicated that the dyes were decolourized and the aromatic amine intermediates formed were degraded to give aliphatic compounds. Scanning Electron Microscope (SEM) and Atomic Force Microscopy (AFM) analysis showed interaction of microbe with the roots of vetiver plants. Toxicity analysis with zebrafish indicated the removal of toxins and teratogens. •Pilot scale plant-microbe sequential anaerobic – aerobic treatment demonstrated.•Real-time textile industry wastewaters treated.•The HRT optimized to 28 h.•Degradation of mixture of dyes and other pollutants observed.•Zebrafish embryos showed less teratogenic effects in the treated water.

We report low temperature acetone and ethanol sensing properties of Al-doped ZnO microrods synthesized using hydrothermal technique. We observe the acetone detection at room temperature as well as ethanol and acetone detection at low temperature of 150 degrees C using Al-doped ZnO microrods. 3 wt% Al-doped ZnO microrods sensor exhibits the highest response of 231 toward 8100 parts per million (ppm) of ethanol at 150 degrees C. The response & recovery time are found to be ultrafast of 60 ms & 870 ms for ethanol and 110 ms & 330 ms for acetone of the Al-doped ZnO microrods at an operating temperature of 150 degrees C, respectively. In addition, sensing mechanism has explained to illuminate the improved sensing performances of Al-doped ZnO microrods. Thus it is revealed that Al-doped ZnO microrods are promising as an ultrafast gas sensor.

Removing wastewater pollutants using semiconducting-based heterogeneous photocatalysis is an advantageous technique because it provides strong redox power charge carriers under sunlight irradiation. In this study, we synthesized a composite of reduced graphene oxide (rGO) and zinc oxide nanorods (ZnO) called rGO@ZnO. We established the formation of type II heterojunction composites by employing various physicochemical characterization techniques. To evaluate the photocatalytic performance of the synthesized rGO@ZnO composite, we tested it for reducing a common wastewater pollutant, para-nitro phenol (PNP), to para-amino phenol (PAP) under both ultraviolet (UV) and visible light irradiances. The rGO(x)@ZnO (x = 0.5-7 wt%) samples, comprising various weights of rGO, were investigated as potential photocatalysts for the reduction of PNP to PAP under visible light irradiation. Among the samples, rGO(5)@ZnO exhibited remarkable photocatalytic activity, achieving a PNP reduction efficiency of approximately 98% within a short duration of four minutes. These results demonstrate an effective strategy and provide fundamental insights into removing high-value-added organic water pollutants.

Camouflage against the danger of electromagnetic radiation is becoming more important due to the rapid growth of wireless communication and electronic devices, which negatively impacts the regular functioning of electrical and electronic equipment. Electromagnetic shielding materials (SMs) that are bendable and ultra-lightweight are hence thought to be crucial for mitigating the detrimental impacts of electromagnetic waves. MXenes have gained a prominent spot among ultra-lightweight shielding materials since the first study on the electromagnetic interference (EMI) shielding of two-dimensional MXenes in 2016, because of a plethora of benefits, including their superior shielding properties, exceptional metallic conductivity from 5 S/cm to over 20,000 S/cm, low density of 2.39 g/cm(3), large specific surface area (SSA) of 18 m(2) g(-1), solution processability, and tunable surface chemistry. To further enhance the inherent EMI shielding (EMIS) capabilities of MXenes, numerous MXene nanocomposites in various structural configurations, including layer-by-layer assembly, laminate and compact frameworks, porous foams, aerogels, and partitioned edifices, have been investigated. This study includes the manufacturing procedure, advantages, disadvantages, and principles in depth, moving from the fundamentals of EMIS through the most recent research on MXene nanocomposites. Based on these breakthroughs, this review seeks to share some insightful information about the multifunctional uses of MXene nanocomposites and their advances as EMI SMs.

Nanosecond pulsed laser deposition (PLD) has been used to grow nanoparticle films of Au on Si and sapphire substrates. The equivalent solid density thickness was measured with a quartz crystal monitor and the ion flux was measured with a time-of-flight Langmuir probe. The ion signal yields the ion energy distribution. The angular distribution of deposited material and the ablated mass per pulse were also measured. These values are incorporated into an isentropic plasma expansion model for a better description of the expansion of the ablated material. Atomic force microscopy and UV/vis optical spectroscopy were used to characterise the films. Atomic force microscopy shows that in the equivalent thickness range 0.5-5 nm the deposited material is nanostructured and the surface coverage increases with increasing equivalent thickness. The optical absorption spectra show the expected surface plasmon resonance, which shifts to longer wavelengths and increases in magnitude as the equivalent thickness is increased. (c) 2007 Elsevier B.V. All rights reserved.

Hydrogenated TiO2 (H:TiO2) is intensively investigated due to its improvement in solar absorption, but there are major issues related to its structural, optical and electronic properties and therefore an easily compatible method of preparation is much needed. In order to clarify this issue we studied TiO2 nanocrystals under the partial pressure of hydrogen to modify the structural, optical and electrical properties and to significantly improve the photocatalytic and photoelectrochemical performance. The hydrogen treated TiO2 nanocrystals contained paramagnetic Ti3+ centers and exhibited a higher visible light absorption cross-section as was confirmed by electron paramagnetic resonance diffuse reflectance spectra measurements and X-ray photoelectron spectroscopy. The hydrogen annealed samples showed a noticeable improvement in photocatalytic activity under visible light (lambda > 380 nm) which was demonstrated by the degradation of methylene blue dye and an improved photoelectrochemical response in terms of high photocurrent density. Ab initio simulations of TiO2 were performed in order to elucidate the conditions under which localized Ti3+ centres rather than delocalized shallow donor states are created upon the reduction of TiO2. Randomly distributed oxygen vacancies lead to localized deep donor states while the occupation of the oxygen vacancies by atomic hydrogen favours the delocalized shallow donor solution. Furthermore, it was found that localization is stabilized at high defect concentrations and destabilized under external pressures. In those cases where localized Ti3+ states are present, the DFT simulations showed a considerable enhancement of the visible light absorption as well as a pronounced broadening of the localized Ti3+ energy levels with increasing defect concentration.

A highly efficient black TiO2-Ag photocatalytic nanocomposite, active under both UV and visible light illumination, was synthesized by decorating the surface of 25 nm TiO2 particles with Ag nanoparticles. The material was obtained via a rapid, one-pot, simple (surfactant and complexing agent free) chemical reduction method using silver nitrate and formaldehyde as a metal salt and reducing agent, respectively. The nanocomposite shows an increase of over 800% in the rate of photocatalytic methylene blue dye degradation, compared to commercial unmodified TiO2, under UV-VIS illumination. Unlike pure TiO2, the nanocomposite exhibits visible light activation, with a corresponding drop in optical reflectance from 100% to less than 10%. The photocatalytic properties were shown to be strongly enhanced by post-reduction annealing heat treatments in air, which were observed to decrease, rather than coarsen, silver particle size, and increase particle distribution. This, accompanied by a variation in the silver surface oxidation states, appear to dramatically affect the photocatalytic efficiency under both UV and visible light. This highly active photocatalyst could have wide ranging applications in water and air pollution remediation and solar fuel production. •A simple one-pot synthesis of a wide spectrum TiO2-Ag photocatalytic nanocomposite is demonstrated.•Heat treatments are shown to have a dramatic effect upon the photocatalytic properties of the nanocomposite.•Different annealing regimes giving optimum photocatalytic performance under UV-VIS and visible only illumination.•An increased particle distribution and decrease in average silver particle diameter was observed upon heating.

Over the past decade or so, alternative energy plays a pivotal role in addressing challenges posed by nature. Polymer electrolyte membrane fuel cell is one of the promising alternative energy and there has been significant research and technological investments done in this field. The key information and future prospective of the field is energy conversion and storage, both of which are essential in order to meet the challenges of global warming and the limited fossil fuel supply. However, polymer membrane in particular plays a crucial role in advancing this technology further. The utilization of conducting polymers in manufacturing membranes combining their electrochemical properties along with mechanical properties is of primary importance to enhance the efficiency of this system. In the present study blends of high impact polystyrene (HIPS) and polyaniline (PAni) were obtained with the aim of producing membranes for fuel cell. HIPS and PAni were dissolved in tetrachloroethylene, a common solvent for both materials. After dissolution, PAni was dispersed in an HIPS polymeric matrix. The membranes were molded on to glass plates using a laminator to keep thickness constant, and the solvent evaporated slowly for 24 h under room temperature. The amount of polyaniline used was 10 and 20 % weight. The electronic and structural properties were carried out using X-ray photoelectron spectroscopy (XPS), Thermogravimetric Analysis (TGA) Raman spectroscopy, Scanning electronic microscopic (SEM). The analysis indicate that PAni incorporation and its dispersion into the polymeric matrix modifies the membranes properties and show improvement in efficiency.

We report the in situ formation of onion-like carbon (OLC) by evaporation from a nanodiamond source under ultra-high vacuum conditions. The OLC is characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) and is found to be highly defective but completely separated. The absence of any signature in XPS, Raman spectra and TEM associated with nanodiamond in the film suggests that the OLC is formed from carbon vapor or by the direct evaporation of only the smallest particles resulting from nanodiamond graphitization. The method thus provides a route to the formation of individually separated OLC nanoparticles.

In this paper we demonstrate the use of atmospheric pressure plasma jet (APPJ) to functionalize the surface of hydrothermally synthesized vertically aligned TiO2 nanorods (TNRs) for photo electrochemical (PEC) application. The TNRs functionalized with the atmospheric pressure He-plasma showed relatively higher crystallinity, improved light absorption, and change in the morphology with additional surface area, leading to an enhanced photocurrent density than that of the untreated. Achieving the PEC performance on par with the best in the literature, this APPJ treatment is shown to be a promising technique to obtain better functionality with TNR kind of materials and many other nano-micro systems for various applications such as PEC hydrogen generation. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

The extensive use of organophosphates (OPs) pollutes the environment, leading to serious health hazards for human beings. The current need is to fabricate a sensing platform that will be sensitive and selective towards the detection of OPs at trace levels in the nM to fM range. With this discussed in the present report, an ultra-sensitive immunosensing platform is developed using digestive-ripened copper oxide quantum dots grafted on a gold microelectrode (Au-mu E) for the impedimetric detection of parathion (PT). The copper oxide quantum dots utilized in this study were of ultra-small size with a radius of approximately 2 to 3 nm and were monodispersed with readily available functional groups for the potential immobilization of antibody parathion (Anti-PT). The miniaturization is achieved by the utilization of Au-mu E and the microfluidic platform utilized has the sample holding capacity of about 2 to 10 mu L. The developed immunosensor provided a wide linear range of detection from 1 mu M to 1 fM. The lower Limit of Detection (LoD) for the developed sensing platform was calculated to be 0.69 fM, with the sensitivity calculated to be 0.14 k Omega/nM/ mm(2). The stability of the sensor was found to be similar to 40 days with good selectivity. The developed sensor has the potential to integrate with a portable device for field applications.

The novel thiourea-functionalized silicon nanoparticles (SiNPs) have been successfully synthesized using allylamine and sulforaphane, an important anticancer drug, followed by a hydrosilylation reaction on the surface of hydrogen terminated SiNPs. Their physiochemical properties have been investigated by photoluminescence emission, Fourier transform infrared spectroscopy (FTIR) and elemental analysis. The MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay has been employed to evaluate in vitro toxicity in human colorectal adenocarcinoma (Caco-2) cells and human normal colon epithelial (CCD) cells. The results show significant toxicity of thiourea SiNPs after 72 h of incubation in the cancer cell line, and the toxicity is concentration dependent and saturated for concentrations above 100 μg/mL. Confocal microscopy images have demonstrated the internalization of thiourea-functionalized SiNPs inside the cells. Flow cytometry data has confirmed receptor-mediated targeting in cancer cells. This nanocomposite takes advantage of the epidermal growth factor receptor (EGFR) active targeting of the ligand in addition to the photoluminescence properties of SiNPs for bioimaging purposes. The results suggest that this novel nanosystem can be extrapolated for active targeting of the receptors that are overexpressed in cancer cells such as EGFR using the targeting characteristics of thiourea-functionalized SiNPs and therefore encourage further investigation and development of anticancer agents specifically exploiting the EGFR inhibitory activity of such nanoparticles.

Use of heterojunctions between two materials having favorable optical and electronic properties can lead to increased photon absorption and charge separation resulting in enhanced photo-electro-chemical energy conversion. In the present study, graphene monolayer nano-flakes are mixed with TiO2 nanoparticles to form nanocomposites having different weight percentages of graphene. The microstructural, morphological and structural properties of the composite samples are investigated using X-ray diffraction, Raman spectroscopy and transmission electron microscopy techniques. Raman studies carried out on samples annealed at different temperatures show the interfacial interaction between TiO2 and graphene, although Anatase TiO2 and graphene maintain their phase integrity. PEC measurements show higher photo-electro-chemical activity in TiO2-graphene nanocomposite at an optimized concentration (2.0 weight percent) due to increased surface area, higher optical absorption in the visible part of the solar spectrum and favorable carrier transport due to increased concentration of defect states and graphene acting as a charge carrier medium.

[Display omitted] •Laser-powder bed fusion (L-PBF) fabrication of functionally graded nickel-titanium (NiTi)-AISI 316L material demonstrated.•Excellent bonding between NiTi and AISI 316L alloys controlled via complex bands of multi-material layers.•Phase and microstructural evolution controlled through the L-PBF settings.•Multi-material phase and microstructure formation/evolution mechanisms elucidated. This study evaluates the phase and microstructural evolution of additively manufactured (AM) Nickel Titanium (NiTi) alloy, across the interface with 316L stainless steel build plate, in order to understand the processing parameter (input power, layer thickness and scan speed), composition, and microstructure interrelationships necessary to achieve excellent multi-material bonding between NiTi and 316L. The effect of the process parameters utilised was characterised using the Scanning Electron Microscope (SEM), Electron Backscatter Diffraction (EBSD), X-ray diffraction (XRD), and Energy-dispersive X-ray spectroscopy (EDX). SEM/EBSD results demonstrated, for the first time, that the microstructure and phase close to the interface was complex and comprised martensite, austenite and Fe phases, sequentially arranged in a layered sandwich pattern across the build direction. This complexity was necessary for excellent bonding. The L-PBF process parameters influenced the diffusion behaviour and the concentration of elements found at the interface. The diffusion rate of Fe and Ti across the NiTi-316L interface was 3.05×10-6m2/s and 3.27×10-8m2/s, respectively, representing a 93.27-fold increase. The observed microstructural and phase evolution is related to the generated interface chemistry and the thermomechanical history related strain resulting from the L-PBF process.