A novel magnetite silica-coated nanoparticle-supported molybdate nanocatalyst has been prepared successfully by a simple co-precipitation method. Prepared nanocatalyst has been characterized by different techniques like Fourier Transmission Infrared Spectroscopy (FT-IR), X-ray diffraction (XRD), Field Emission Scanning Electron Microscope (FE-SEM), and Energy Dispersive X-ray Spectroscopy (EDX). Further, the catalytic activity of the nanocatalyst was explored for N-formylation reactions under solvent-free conditions. Interestingly, the catalyst could be reused for 10 cycles, and only 2 mol % of the catalyst was sufficient to catalyze the N-formylation reaction at 700C under solvent-free conditions.

Significant advancement in photoelectrochemical water splitting current is observed using uniquely evolved n/n junction bilayered nano-hetero-structured thin films, WO3/Yb-Mo-BiVO4, as photoanode. Films, synthesized over F:SnO2 glass substrates were characterized by UV–Visible spectroscopy, X-ray diffractometry, atomic force microscopy, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. Using thin films (2% Mo and 4% Yb incorporation) as working electrode in PEC cell, in conjunction with platinum counter electrode, saturated calomel reference electrode, aqueous solution (200 cm3) of K2HPO4 (1.0 M, pH 8.7, temperature 31 ± 3.6 ℃) and 150 W Xenon Arc lamp for illumination, ~ 227–950% increase in Iph is recorded against monolayered pristine films of WO3 and BiVO4. Marked rise in photoelectrochemical cell photocurrent is attributable to expanded absorption of light, coupled with internal electric field in Yb–Mo-incorporated n/n hetero-junction films, reduced electrical resistivity and optimally raised surface roughness that favoured the separation and transfer of photogenerated charge carriers across electrode/electrolyte interface.

Nanoparticles today have the upper hand in its manufacturing desirability in more or less every aspect of the working areas, from industrial and commercial to self-care products. In this paper, the applicational prospects of varistors for the composite mixture of rGO and Ag-nanopowders were studied via samples with varying compositions. Hummers modified method and burst method were employed for the synthetisation of GO, rGO, and Ag-nanopowders, respectively. The structural nature and electrical behaviour were understood by the means of variegated characterisations. The purity of GO and rGO were confirmed via Raman analysis. XRD and FTIR exhibited the attributed peak values for GO and rGO, Ag-nanopowders. The topographical and elemental details were acquired through FESEM and EDX studies, which talked about the wrinkled paper-like structure for GO and rGO and spherical structural nature of Ag. Current–voltage plot was studied for the better understanding of the electrical inhabitation. It was observed that rGO + Ag, being two constituent networks, gave small values but still showed an increase, which means if used with complex arrangement, they have the possibility to be considered in the material fabrication for high-voltage varistors domains.

Novel silica-coated ferrite nanoparticles supported with montmorillonite (K10) have been prepared successfully by using a simple impregnation method. Further, these nanoparticles were characterized by using different analytical methods like FT-IR, PXRD, EDS, and FE-SEM techniques. In addition, these nanoparticles have been explored for their catalytic activity for the O, N, and S-acylation reactions under solvent-free conditions which gave moderate to excellent yields in a much shorter reaction time. Moreover, these nanoparticles could easily be separated out from the reaction medium after the reaction completion by using an external magnetic field and have been re-used for 10 cycles without any significant loss of the catalytic activity.

In current study, Cu capped Cu2O nanoparticles (Cu-Cu2O) was synthesized using trioctylamine which is playing a dual role as a hydrolyzing agent as well as capping agent. Temperature and time dependent studies were also performed to monitor different phase formation. As synthesized material was charac-terized by X-ray diffraction (XRD) for phase determination, crystalline size and morphological investiga-tion. Transmission electron microscopy (TEM) images revels the morphology of the nanoparticles was cubic which leads to spherical at higher temperature. Photocatalytic mineralization studies were carried out in the presence of Congo Red (CR) dye, organic molecules decontamination from aquatic environment with 98.7% mineralization. (C) 2020 Elsevier B.V. All rights reserved.

In this present study, nucleation controlled vertically oriented Zinc Oxide nanorod (ZNR) array based Photoanodes was successfully synthesized on conductive substrate by hydrothermal method for Photoelectrochemical (PEC) cell. We have investigated the effect of ammonia during the synthesis on morphology of ZNR and its effect on current-voltage characteristics of PEC cell. Synthesized ZNR were subjected to X-ray diffraction (XRD), UV-Visible spectroscopy, Field emission scanning electron microscopy (FE-SEM), Energy dispersion spectroscopy (EDX) for microstructural characterization. Presence of single (002) peak in XRD pattern confirms vertical c-axis oriented growth of ZnO rods. FE-SEM images revealed that concentration of ammonia had marked effect on crystallization, morphology and density of ZnO rods. PEC properties were investigated by using ZnO rods as photoanode in three electrode cells under AM 1.5G illumination. Morphology and crystallization of ZnO rods had marked effect on current-voltage characteristics. (C) 2020 Elsevier B.V. All rights reserved.

In present study, ZnO-SnO2 nanocomposite was synthesized by co-precipitation method and its sensing properties with respect to carbon monoxide gas were investigated. X-ray diffraction pattern shows the exhaustive evolution of hexagonal wurtzite phase of ZnO and rutile phase of SnO2. Morphological study was done by FE-SEM and optical characterization was done by UV-visible spectrophotometer. To study the sensing properties, material was layered on conducting substrate and resistance was recorded in the presence of air and CO gas at different operating temperature. Sensing responses of pure ZnO and ZnO-SnO2 composite was also compared. ZnO-SnO2 showed much enhanced response along with better response and recovery time compared to pure ZnO.

Pyranopyrazoles are known to show various biological activities, hence is an important class of heterocyclic compounds. Herein we are reporting very first time a convenient and reliable L-histidine catalyzed one pot synthesis of a series of pyrano[2,3-c]pyrazoles from hydrazines, ethyl acetoacetate, malano nitrile and aromatic aldehydes. The reaction presumably involves a sequence of hydrazine formation, arylidine formation, Michael addition followed by cyclization. The yields are high and the reaction takes 1-2 hours for completion, moreover reusability of the catalyst is four times without effecting much on the percentage yield formation.

In the present study, ZnO-Fe2O3 heterojunction has been successfully synthesized by co-precipitation method for photocatalytic degradation of Victoria blue dye. The synthesized samples were subjected to XRD for microstructural characterization and scanning electron microscopy for morphological investigation. The typical X-ray diffraction pattern shows exhaustive evolution of hexagonal wurtzite phase of ZnO and alpha-Fe2O3 having crystalline in the range of 34-54 nm. The synthesized samples were applied for degradation of victoria blue dye under UV illumination. ZnO-Fe2O3 heterojunction showed higher photocatalytic activity for dye degradation compared to bare ZnO. This rise in photocatalytic activity can be attributed to enhanced charge separation derived from coupling of ZnO and Fe2O3. In this manuscript, the effect of photocatalyst dose, irradiation time and initial dye concentration on photodegradation of dye is reported in detail.

In the present study Readymade Graphene oxide (GO) has been coated using electrochemical deposition technique [1] on to the conducting glass (ITO) substrate. Raman spectra generated D and G Peaks obtained at 1346 and 1575 cm(-1) confirmed the presence of GO [2]. The UV-Visible absorption measurements provided absorption peak at 262 nm and the Tauc plots yielded band-gap energy of sample around 3.9 eV. The PEC measurements involved determination of current-voltage (I-V) characteristics, both under darkness as well as under illumination. The photocurrent of 1.21 inA/cm(-2) at 0.5 V applied voltage (vs. saturated calomel electrode), was recorded under the illumination of 150 Wcm(-2) (Xenon arc lamp; Oriel, USA). The photocurrent values were utilized further to calculate applied bias photon-to-current efficiency(% ABPE), which was estimated to 0.98 % at 0.5 V bias.

In the quest for achieving the desired efficiency, balanced economics and prolonged durability of the photoelectrochemical (PEC) system for hydrogen generation, heterostructures consisting of two or more semiconductors are being looked upon as favourite material alternatives. This communication describes the basic principles involved and summarizes most of the work done in this domain. Band gap, electronic band edge alignment of the materials with each other and with the redox potential of water, lattice mismatch of the materials and optimization of thickness of each layer at the junction in the PEC devices appear to be crucial for attaining enhanced photoresponse and efficiency. Based on the studies reported in the literature and from our own studies, heterojunction systems are considered as effective tool towards extending the spectrum to the visible range and for effective separation of charge carriers leading to development of efficient solar hydrogen production system.

The effects of high electronic energy deposition on the structure, surface topography, optical property and photoelectrochemical behavior of barium titanate thin (BaTiO3) films have been investigated by irradiating films with 120 MeV Ag9+ ions at different ion fluences in the range of 1 x 10(11)-3 x 10(12) ions cm(-2). Barium titanate thin films were deposited on indium tin oxide-coated glass substrate by sol-gel spin coating method. The structure of the film was crystalline with tetragonal phase. Surface topography was studied by atomic force microscopy detailing the values of roughness of the films. Maximum photocurrent density of 1.78 mA cm(-2) at 0.4 V/SCE and applied bias photon-to-current efficiency (ABPE) of 0.91% was observed for BaTiO3 film irradiated at 1 x 10(11) ions cm(-2). (C) 2012 Elsevier B.V. All rights reserved.

Thin films of nanocrystalline Zn1-xRuxO are deposited on ITO substrate by sol-gel. XRD and EDX analysis indicated dominant evolution of wurtzite ZnO with crystallite size in the range 26-43 nm. with no evidence of phase segregation, Ru insertion in the host lattice is probably indicated by distortion in lattice parameters and concomitant rise in microstrain and dislocation density. SEM images indicated homogenous and continuous growth of nanocrystallites. AFM images confirmed pillar like growth of crystallites along c-axis. Ru incorporation (1, 3, 5 and 7% at.) made film surface rougher, nevertheless roughness decreased with rise in Ru concentration. Ru incorporation at low concentrations significantly improved PEC response of films. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Nanostructured ZnO is a promising material for solar light driven photoelectrochemical splitting of water to produce hydrogen. With a band gap around 3.3 eV, it can easily generate required photopotential for electrolysis of water. However, its high band gap does not permit efficient absorption of solar light. To overcome this limitation, several approaches are being tried. A popular approach is its sensitisation with a dye having λ max in the visible region. In an innovative approach, authors irradiated sol-gel derived nanostructured ZnO films by 120 MeV Ag 9+ ions to induce structural defects that might shift absorption threshold in the visible region. This report presents, with regard to PEC splitting of water, a comparison of SHI irradiated vis-à-vis dye-sensitised films of ZnO. Films were subjected to XRD, SEM and Mott-Schottky analysis and optical characterisation. For PEC studies, these were used in conjunction with Pt counter electrode, saturated calomel reference electrode and 150 W Xenon arc light source.

We use a combination of experiments and first principles density functional theory based calculations in a study of the photoelectrocheinical properties of Fe-doped BaTiO3 nanopowder. BaTiO3 with 0.5-4.0 atom % Fe doping is synthesized via a polymeric precursor route and characterized with X-ray diffractometry (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), UV-vis spectroscopy, and Mossbauer spectroscopy. We find a red shift of 0.39 eV in the UV-vis spectrum and hence an improved photoelectrochemical activity in the visible range upon Fe doping in BaTiO3. The origin of the observed activity in the visible range is traced through the calculated electronic structure to the electronic states associated with Fe at energies within the band gap. A reasonable agreement between the changes in measured spectra and those in calculated electronic structure augurs well for a judicious use of first-principles calculations in screening of dopants in the design of doped oxide materials with enhanced photoelectrochemical activity, such as that of Fe-doped BaTiO3 demonstrated here.

Nanocrystalline thin films of Zn1−xMxO (M=Ni, Cr) were deposited on glass substrate by sol–gel method. To a solution of zinc acetate 2-hydrate in dimethyl formamide, calculated quantities of nickel nitrate or chromium acetate were added. The clear solution, obtained after 2h of continuous stirring, was coated on conducting glass (ITO plates). After preannealing at 250°C to remove organic impurities, films were sintered at 400, 500 and 600°C. XRD analysis reveals dominant evolution of hexagonal ZnO with a possible simultaneous growth of meta-stable cubic ZnO. AFM analysis indicated preferential growth of nanocrystallites along c-axis, while SEM analysis confirmed films having uniform morphology. Optical characterization led to two band gap values; one matching with the band gap of bulk ZnO and the second slightly higher, which suggest quantum confinement effect in nanocrystallites. Ni and Cr incorporation influenced the two band gap energies differently. Photoelectrochemical (PEC) splitting of water was attempted, using prepared thin films as working electrode, in conjunction with Pt counter electrode and saturated calomel reference electrode along with 150W Xenon Arc light source and aqueous solution of NaOH (0.01M). Results indicate Ni:ZnO films yielding improved photoresponse compared to Cr:ZnO films. Ni:ZnO (5% at.) films sintered at 600°C resulted in significantly enhanced photocurrent due to improved optical absorption and decrease in resistivity.

This paper deals with a study on the effect of 120 MeV Ag9+ ion irradiation on photoelectrochemical properties of SrTiO3 thin films deposited on Indium doped Tin Oxide (ITO) coated glass by sol gel spin-coating technique. The structural evolution in the pristine and irradiated films was determined by X-ray diffraction and X-ray photoelectron spectroscopy. Surface morphology was studied by Atomic Force Microscopy (MM) and optical measurements were done by UV-visible absorption spectroscopy. Irradiation of SrTiO3 thin films was found to be effective in improving its photoelectrochemical properties. A noticeable decrease in the average grain diameter from 36 to 26 nm, reduction in bandgap from 3.55 to 3.43 eV and increase in roughness after irradiation contributed in enhancing photoelectrochemical activity of SrTiO3 thin films. Thin films irradiated at fluence 3 x 10(12) ions cm(-2), when used in PEC cell exhibited enhanced photocurrent of 0.16 mA cm(-2) at zero bias conditions, which was four times higher than that of the unirradiated sample. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Cu-incorporated nanocrystalline ZnO thin films were deposited on glass substrate by sol–gel. To a solution of zinc acetate 2-hydrate in dimethyl formamide, calculated quantities of copper acetate were added. The clear solution, obtained after 2 h of continuous stirring, was coated on ITO plates. Pre-annealing at 250 °C was followed by sintering at 400, 500, and 600 °C. XRD analysis revealed dominant evolution of hexagonal ZnO with a possible simultaneous growth of meta-stable cubic ZnO. AFM and SEM analysis indicated preferential growth of nanocrystallites along c-axis. Optical characterization led to two prominent absorption thresholds in the UV region; one matching with the band gap of bulk ZnO and the second at slightly higher energy, suggesting quantum confinement effect in nanocrystallites. Cu incorporation influenced the two band gap energies differently. Photoelectrochemical splitting of water using 1% at. Cu–ZnO film sintered at 600 °C resulted in 141% gain in photocurrent at zero bias.