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Indium selenide (γ-In2Se3) films were prepared using RF magnetron sputtering. Influence of deposition time on structural, optical, morphological, and photoelectrochemical (PEC) performance was studied. Formation of γ-In2Se3 is confirmed by low angle XRD, Raman spectroscopy, and XPS analysis. Surface morphology investigated using FE-SEM shows that γ-In2Se3 films are uniform and have a dense grain structure, without cracks and holes. Optical properties show that γ-In2Se3films absorb mainly in the UV region, and the bandgap energy decreases from 2.81 to 2.27 eV as deposition duration increases. Conduction and valance band-edge potential values show that γ-In2Se3 films are suitable for photoelectrochemical hydrogen evolution. PEC activity of γ-In2Se3 photoanodes was evaluated using linear sweep voltammetry (LSV), and there was an increase in photocurrent density with deposition time. Electron impedance spectroscopy (EIS) analysis revealed that γ-In2Se3 photoanodes had high charge transfer resistance, and it decreases with deposition time, which leads to improved PEC performance. Investigation of Mott Schottky's (MS) results shows a shifting of flat band potential towards negative potential, suggesting movement of fermi level towards conduction band edge. Carrier density increases from 3.7 × 1019 cm−3 to 8.9 × 1020 cm−3 and depletion layer width of γ-In2Se3 photoanodes are found in the range of ~ 2.67–9.10 nm. The gradual increase in electron lifetime indicates a decrease in the recombination rate of photo-generated charge carriers. An increase in time-dependent photocurrent density reveals that γ-In2Se3 films have effective electron–hole separation. Our work demonstrates that γ-In2Se3 can be a probable candidate for PEC water splitting and opto-electronic applications.

In this paper, Au plasmons and their synergistic effects with ZnO nanorods (ZNs) have been investigated for photoelectrochemical (PEC) water splitting application. Au plasmons and ZNs are deposited electrochemically. Au modified nanostructures have absorption in the visible region as plasmons enhance charge transfer and inhibit charge recombination. ZNs modified with Au (deposition duration ∼ 60 s) has a photo-current density of ∼ 660 µA cm-2, at a bias of 1.0V/SCE. X-ray diffraction and scanning electron microscopy were used to study the structure and surface morphology of fabricated photoanodes. UV-Visible absorption and Photoluminescence spectroscopy were used for optical characterization. We have recorded current-voltage measurements and photo-conversion efficiency measurements to substantiate our observations of the synthesized photoanodes for prospective application in PEC splitting of water. We have also carried out Mott-Schottky, and electrochemical impedance spectroscopy analysis. The analysis reveals that Au modified ZNs based photoanodes are a better proposition than their bare counterparts for PEC water splitting application.

Herein, by using chemical methods such as successive ionic layer adsorption and reaction (SILAR) and spin coating we have demonstrated a novel strategy for the synthesis of ternary hybrid to study photoelectrochemical (PEC) performance. To the best of our knowledge, for the first time we have represented a case study of achieving optimum SILAR cycles for Ag nanoparticles decoration on ZnO nanorods and a discussion was made on a role of multi-walled carbon nanotube (MWCNT) as a top layer over Ag–ZnO nanostructures for better PEC performance. Firstly, Ag nanoparticles loading over SILAR grown ZnO nanorods was varied for different SILAR cycles to optimize better photocurrent. This Ag–ZnO hybrid showed higher photocurrent density of 0.45 mA/cm2 at 1 V bias (vs SCE) and photoconversion efficiency (PCE) of 0.21% (0.45 V vs SCE). Thereafter, MWCNTs were garnished by using spin coating as a top layer on Ag–ZnO hybrid leading to the formation of ternary hybrid of MWCNT–Ag–ZnO for further enhancement of PEC activity. We believe that top layer of MWCNT plays a vital role of electron and hole transfer and bridges Ag decorated ZnO nanorods together leading to well-connected conducting pathways for efficient charge collection and transport. The appropriate band bending of MWCNT–Ag–ZnO hybrid leads to the formation of active interface helping out in charge separation leading to excellent photocurrent density of 0.56 mA/cm2 at 1 V bias (vs SCE) and photoconversion efficiency of 0.26% (0.45 V vs SCE). Enhanced light harvesting, higher donor density, appropriate band bending, lowest charge transfer radius of C–Ag–ZnO hybrid signifies that efficient charge transfer and restriction to charge recombination leading to the enhanced PEC performance.

Zinc oxide nano-sheets (ZNS) loaded with Zeolitic Imidazole Framework 8 (ZIF8) nanocrystals, i.e. (ZNS@ZIF8) thin films, were successfully synthesized using electrodeposition and facile chemical bath deposition (CBD) for photoelectrochemical (PEC) splitting of water. The formation of ZNS nano-sheets and ZIF8 nano-crystals has been confirmed by field emission scanning electron microscopy (FE-SEM), low angle X-ray diffraction (XRD), micro-Raman spectroscopy, and Fourier transform infrared (FTIR) spectroscopy analysis. PEC activity of ZNS@ZIF8 photoanodes was evaluated using the linear sweep voltammetry (LSV) technique, and the photocurrent density is significantly enhanced when ZNS are decorated with ZIF8 nanocrystals. Electrochemical impedance spectroscopy (EIS) revealed that ZNS@ZIF8 had low charge transfer resistance compared to pristine ZNS counterparts. This led to considerably improved PEC performance of ZNS@ZIF8. Mott–Schottky (M–S) analysis of ZNS and ZNS@ZIF8 revealed a shift of flat band potential for the ZNS and ZNS@ZIF8 photoanodes, respectively. The shift of flat band potential indicates a clear shift in the Fermi level towards the conduction band, leading to an efficient charge transfer process across the electrolyte. The carrier density of ZNS and ZNS@ZIF8 photoanodes increases from 3.67 × 1019 cm−3 to 4.11 × 1020 cm−3. The enhanced applied bias photon conversion efficiency (ABPE) of ZNS@ZIF8 photoanodes suggests that ZNS@ZIF8 can be a prospective candidate for PEC and optoelectronic applications.

Morphological forms of ZnO nanostructures play a vital role in deciding properties such as high internal surface area, efficient light scattering and harvesting, lowest charge transfer resistance, etc. which are important for photoelectrochemical (PEC) performance. Herein successful deposition of well oriented ZnO nanorods thin films over fluorine doped tin oxide (FTO) coated glass substrate is achieved by using simple, soft solution and scalable method known as successive ionic layer adsorption and reaction (SILAR). For the first time a compact ZnO layer over large area is deposited in one step synthesis approach, without any assistance of seed layer, by using hydrazine hydrate as a source of hydroxyl ions. The plausible growth mechanism of the morphological variation (alignment and orientation) happening with increasing SILAR cycles and its consequence on PEC performance are discussed in detail. All ZnO thin films show wurtzite crystal structure, however variations in their texture coefficients were found with SILAR cycles, which turns out to be a major aspect for PEC application. Anodic shift was observed in flat band potential values with increment in number of SILAR cycles. The ZnO thin films deposited for 120 cycles showed preferential orientation along (0002) plane and showed better PEC performance with photocurrent of 0.19 mA/cm2 (1 V) and maximum photo conversion efficiency of 0.084% at 0.45 V. On the other hand, film deposited for 60 (photocurrent of 0.11 mA/cm2 (1 V); efficiency of 0.055%) and 180 cycles (photocurrent of 0.15 mA/cm2 (1 V); efficiency of 0.063%) demonstrated inferior PEC performance.

One step electrodeposition method has been used to realize highly porous ZnO pin hole (ZP) and ZnO rosette sheets (ZS) nanostructure based photo-anodes for efficient photoelectrochemical (PEC) splitting of water. Electrodeposited ZP and ZS based photo-anodes exhibit enhanced photocurrent density of 0.62 mA/cm2 and 0.76 mA/cm2 respectively (at a bias of 0.75 V). Further on hydrothermal amination (A), these electrodeposited ZP and ZS (A-ZP and A-ZS) nanostructure based photo-anodes had shown enhanced photocurrent density of 1.02 mA/cm2 and 1.27 mA/cm2, respectively. Surface morphology, evolution and elemental study were done using FESEM and EDX. Raman spectra of aminated photo-anodes have peaks at ∼270 cm−1 and ∼511 cm−1 related to stretching vibration mode between Zn N and Zn O. The peaks at wave number ∼558 cm−1 and ∼571 cm−1 is due to formation of Zn C bonds and because of complex defects respectively. ZnO exhibits low PEC activity, but on nano-structuring in the form of ZP and ZS improves its light absorption capacity. Hydrothermal amination red shifts (∼25 nm) the absorption band at ∼ 425 nm. The N and C act as electron reservoirs in A-ZP and A-ZS photo-anodes and efficiently separate the photo-generated electron/hole pairs and restrain charge recombination to generate photo-reactive sites. Electrochemical impedance spectroscopy (EIS) revealed that A-ZP and A-ZS had low charge transfer resistance compared to their bare counterparts. This lead to considerably improved PEC performance. An unprecedented increase in IPCE values in A-ZP and A-ZS can be assigned to the decrease in band gap and thereby significant enhancement in photocurrent density. These result in to proper charge segregation and improved charge transportation. The maximum value of IPCE is 9.6% for A-ZS sample and it is also clear that ZP and ZS nanostructured film have higher IPCE values at ∼400 nm than traditional ZnO thin film. A-ZP and A-ZS based photo-anodes have exhibited enhanced PEC performance as evident from IPCE measurements and thus can be a prospective candidate for PEC and optoelectronic applications.

Herein, dye sensitized solar cell (DSSC) application of precipitation assisted-hydrothermally derived TiO2 nanostructures is realized through extensive analysis. The TiO2 nanostructures are derived by precipitation reaction of titanium tetra-isopropoxide (TTIP) followed by annealing of resultant precipitate at 300°C and then hydrothermal reaction of as-annealed precipitate in alkaline media at 120, 130, 140 and 150 °C for 24 hr. The resultant nano-structured powders are examined by XRD, UV-Visible spectroscopy and FESEM. The material characterization of as-derived nanostructured powders revealed the crystallization of phase pure TiO2 nanostructures like nanoparticles (NPs), nanochains (NCs) and nanotubes (NTs) with anatase symmetry. The N719 sensitized solar cells are fabricated by using photoanodes prepared with as-derived TiO2 nano-structured powders and electrolyte solution (0.05 M iodine, 0.5 M LiI, and 0.5 M 4-tertbutylpyridinein 3-methoxypropionitrile). The DSSC characteristics are obtained by using solar simulator under illumination of as-fabricated cells with light of AM 1.5 (100 mWcm-2) intensity. The photoconversion efficiency is found to be increasing from 1.10 to 3.06 % by changing the morphological features from nanoparticles (NPs) to nanotubes (NTs). The profound effect of change in morphology of TiO2 based photoanode on photoconversion efficiency is found.

Solar energy can be tapped and stored efficiently using photoelectrochemical (PEC) cells. PEC cell utilizes influx of photons to drive uphill chemical reactions and thereby transforming their inherent energy into chemicals bonds. PEC reaction is one of the most important reactions for generating hydrogen and oxygen. Moreover, as the reaction is reversed and hydrogen is combusted in presence of oxygen; water is obtained as by-product. A lot of research efforts are underway for realizing efficient photoactive material that can absorb sunlight in visible region and has proper straddling band edges that can oxidize and reduce water. The water oxidation half cell reaction also restrains the technology as water oxidation is slow at the surface of photoanodes compared to other loss processes. Semiconductor (SC) photoanodes modified with earth abundant electrocatalyst (EC) can be a important proposition for realizing electrodes with high photocatalytic activity and stability for proficient PEC splitting of water. This approach allows optimization of different processes such as photon absorption, charge separation and surface catalysis independently. The PEC reactions are catalyzed by electrocatalyst by lowering the activation energy. For PEC H2 generation reaction, the main earth abundant electrocatalyst comprises of transition metal chalcogenides, carbides, phosphides, whereas for O2 generation mixed transition metal oxides can be utilized. Bifunctional (HER/OER) electrocatalyst such as NiFeOOH and Co-Mn oxide nanoparticle can be used for PEC splitting of water. Hybridization of composite photoanodes, provide flexibility for adjustment of different components with different properties but raises new issues at the interfacial forefront.

The influence of Ag plasmons and reduced graphene oxide (RGO) on ZnO nanorods (Z-NRs)-based photoanodes for photoelectrochemical splitting of water is the main focus of the present experimental study. Plasmonic layer of Ag is incorporated either as a base (Ag-Z-NRs) layer or as a top layer (Z-NRs-Ag) in an electrochemically deposited Z-NRs-based photoanodes. Z-NRs-Ag photoanodes exhibited better optical absorption as plasmonic layer stimulates charge transfer and restrain charge recombination. It had shown the photocurrent density of ~0.79 mA cm−2, at a bias of 1.4 V/RHE. A mediator layer of RGO when introduced in Z-NRs-Ag photoanodes synergistically with Ag plasmons enhances the photocurrent density to ~1.3 mA cm−2 at a bias of 1.4 V/RHE. Structure and surface morphology of the synthesized photoanodes was studied using x-ray diffraction and field emission scanning electron microscopy. Elemental analysis and optical characterization was done using energy-dispersive x-ray analysis, UV–Visible absorption spectroscopy and Raman spectroscopy. The current–voltage characteristics, electrochemical impedance spectroscopy, Mott–Schottky analysis, photoconversion efficiency and incident photon to current conversion efficiency measurements have been used to substantiate our observations of synthesized photoanodes.

We report synthesis and characterization of ultrathin cobalt sulfide nanoflakes (CoSx-NFs) sensitized zinc oxide nanorods (Z-NRs) array based thin films and their implementation as photoanodes for photoelectrochemical (PEC) splitting of water. Cobalt sulfide nanoflakes-sensitized zinc oxide nanorods (CoSx-NFs/Z-NRs) array based photoanodes were grown on fluorine-doped tin oxide substrate by a simple and versatile electrodeposition method. Maximum conversion efficiency of PEC cell was found 0.37% with a photocurrent density of 0.48 mA/cm2 at a bias of 0.3 V/SCE in CoSx-NFs/Z-NRs-15 (loading of CoSx-NFs on Z-NRs by cyclic voltammetry for 15 cycles) based photoanodes. The photo-activity is 2.7 times larger than that of Z-NRs array-based photoanode. Experimental results reveal that sensitization by CoSx-NFs causes red shift in the band gap energy of Z-NRs photoanode. Lower band gap energy, suitable band redox potential, and marked absorption in visible light make CoSx-NFs/Z-NRs-15 thin films a promising material for photoanodes in PEC cells. A detailed analysis using X-ray diffraction (XRD), UV-Visible (UV-Visible) spectroscopy, field emission scanning electron microscope (FE-SEM), energy-dispersive analysis (EDX), electron impedance spectroscopy (EIS), Mott-Schottky (MS) analysis, applied bias photon-to-current conversion efficiency (ABPE), and incident photon to current conversion efficiency (IPCE) measurements has been carried out to substantiate our observations. The excellent performance of CoSx-NFs/Z-NRs allows the composite photoelectrode to have many potential applications as a photoanode material for H2 production, nanoflakes-sensitized solar cells, and UV photodetector.

We report synthesis and use of Chlorophyll‐a/ZnO nanorod based hybrid photoanodes for photoelectrohemical (PEC) activity. Hybrid photoanodes consist of vertically oriented self ordered nanorod array of ZnO fabricated via electrodeposition followed by sensitization with chlorophyll‐a. Under AM 1.5 illumination (100 W/cm2), at 0.75 V bias, the hybrid photoanodes achieved a photocurrent density of 0.67 mA/cm2 which is ∼2.6 times increase over bare ZnO nanorods (0.26 mA/cm2). To the best of our knowledge, this is the first report on the use of Chlorophyll‐a/ZnO nanorod based hybrid electrodes in photoelectrochemical cells, with potential applications in switching and sensing.

The present work represents successful synthesis of CdTe-sensitized TiO2 nanoarray thin films by two simple chemical routes. Here, we report the sensitization of TiO2 nanoarrays with CdTe nanoparticles through the electrodeposition technique at ambient condition. The electrodeposition of 30 min leads to the formation of shell of CdTe nanoparticles over TiO2 nanoarrays. This core-shell formation structure was further confirmed by TEM and HR-TEM analysis. Optical absorption and photoelectrochemical study revealed that the TiO2/CdTe core-shell heterostructure extend the absorption edge of titania in the visible region of solar spectrum; it also facilitates the efficient charge transport and reduces the recombination losses. The maximum photoconversion efficiency of 0.32% is obtained for TiO2/CdTe core-shell semiconductor-sensitized solar cells (SSSCs).

Carbon functionalized bismuth vanadate (BVO) photoanodes were synthesized using simple wet chemical process. To ascertain and determine various aspects of synthesized photoanodes, different types of characterization and measurements such as, X-ray Diffraction (XRD), Field emission scanning electron microscope (FE-SEM), UV–Visible (UV–Vis), Raman, Photoelectrochemical (PEC), Mott-Schottky (MS), and Electron Impedance Spectroscopy (EIS) have been carried out. Carbon functionalized BVO (C-BVO) photoanodes demonstrated superior photoconversion efficiency (η∼0.38%) and short circuit current (JSC∼0.50 mA/cm2 at 0.5 V vs. SCE) compared to pristine BVO. Bare BVO based PEC OR and AND logic gates have also been designed using pulsed white light beams. The PEC response reveals that for a white light beam with peak pump intensity of 100 mW/cm2, a photocurrent density of 83 μA/cm2 is generated at a bias of ∼0.5 V vs. SCE. Moreover, by tuning bias the photocurrent response can be inverted and further utilized to realize different logic operations simultaneously. The present study paves a new way for bismuth vanadate-based PEC computing devices.

Solution-based controlled morphological 1D ZnO nanorods (NRs) and nanotubes (NTs) were synthesized by a very simple and versatile electrodeposition method. The X-ray diffraction, UV-Vis spectroscopy, and scanning electron microscopy were used to characterize phase, composition quality, and optical properties of synthesized ZnO NRs and NTs. Growth mechanism, morphological evolutions, structural intactness of ZnO NRs, NTs, and their subsequent use as photoanode for efficient photoelectrochemical splitting of water are discussed in detail. ZnO NTs exhibited markedly enhanced photocurrent density of 0.67 mA/cm2 at 0.5 V vs SCE over NRs and also benefited from more negative flat band potential for hydrogen evolution.

We have successfully grown template and buffer free ZnO nanorod films via chloride medium by controlling bath temperature in a simple and cost effective electrochemical deposition method. Thin films of ZnO nano-rods were obtained by applying a potential of −0.75 V by employing Ag/AgCl reference electrode for 4 h of deposition time. The CV measurements were carried out to determine potential required to deposit ZnO nanorod films whereas chronoamperometry studies were carried out to investigate current and time required to deposit ZnO nanorod films. The formation of ZnO nanorod has been confirmed by scanning electron microscopy (SEM) and Raman spectroscopy. Low angle XRD analysis confirms that ZnO nanorod films have preferred orientation along (101) direction with hexagonal wurtzite crystal structure. The SEM micrographs show nice surface morphology with uniform, dense and highly crystalline hexagonal ZnO nanorods formation. Bath temperature has a little influence on the orientation of nanorods but has a great impact on their aspect ratio. Increase in bath temperature show improvement in crystallinity, increase in diameter and uniform distribution of nanorods. Compositional analysis shows that the amount of oxygen is ~49.35 % and that of Zn is ~50.65 %. The optical band gap values were found to be 3.19 and 3.26 eV for ZnO nanorods prepared at bath temperature 70 and 80 °C respectively. These results indicate that by controlling the bath temperature band gap of ZnO nanorods can be tailored. The obtained results suggest that it is possible to synthesize ZnO nanorod films by a simple, cost effective electrodeposition process which can be useful for opto-electronic devices fabrication.

To meet the future energy demand, Hydrogen has been accepted as a fuel for future. Out of several renewable methods to produce hydrogen, solar assisted splitting of water (Photoelectrochemical splitting of water) is emerging as a most desired method to produce hydrogen which is a advancement of Photovoltaic process. However, the efficiency of PEC cell is a matter of concern. Various strategies have been adopted by different researchers to increase the efficiency of the system especially using nanotechnology as a tool. In this article, attempts have been made to summarise different approaches applied to obtain effective and viable photoelectrochemical system for splitting water to obtain hydrogen an energy carrier.

ZnO is one of the most promising candidate for photoelectrochemical splitting of water for hydrogen production. To increase the efficiency of ZnO based photoelectrochemical cell, its band-gap and band edges should be tailored to match visible light spectra and water redox potential respectively. In this paper, First-principles density functional theory calculations have been performed to evaluate the effect of non-metal dopants on electronic properties of ZnO. The model structures of X-doped ZnO were constructed using 32-atom 2 x 2 x 2 supercell of wurtzite ZnO with one O atom replaced with X (carbon C, phosphorus P). With respect to the electronic band structure, C (2p), P (3p) states are located above the valence band maximum of ZnO and mixing of these states is feeble to produce significant band gap narrowing. Doping of these non-metals dopants helps in the creation of isolated states which enhances visible light absorption of ZnO. Our theoretical calculations are consistent with the experimental results of C (P) doped ZnO and fully explains its visible light activity on non-metal doping.

In this work, we have studied the influence of substrate temperature on structural, morphology optical, and electrical properties of CdTe thin films deposited by RF magnetron sputtering. Films were analyzed by using variety of techniques such as low angle X-ray Diffraction, UV–Visible spectroscopy, Raman spectroscopy, Field emission scanning electron microscopy (FE-SEM), Energy-dispersive X-ray spectroscopy (EDAX) Hall Measurement etc. Low angle XRD analysis showed that CdTe films are polycrystalline and has cubic structure with preferred orientation is along (111) direction. Raman scattering studies revealed the presence of single phase CdTe over the entire range of substrate temperature studied. The FE-SEM analysis showed that CdTe growth process occurred predominantly by grain growth and not through the layer-by-layer mode. Compositional analysis carried out using EDAX suggests that CdTe films deposited at low substrate temperatures are Te rich and that at higher temperatures is Cd rich. Electrical resistivity of CdTe films decreases with increase in substrate temperature and whereas positive increase in Hall coefficient suggests as-deposited CdTe films are p-type. The UV–Visible spectroscopy analysis showed that the band gap increases from 1.47 to 1.51 eV when the substrate temperature increased from 50 to 300 °C. Such optimum band gap CdTe can be use as absorber material in photovoltaic applications like the CdS/CdTe and ZnO/CdTe solar cells.

Influence of filament temperature (TFil) on the structural, morphology, optical and electrical properties of silicon carbide (SiC) films deposited by using hot wire chemical vapor deposition technique has been investigated. Characterization of these films by low angle XRD, Raman scattering, XPS and TEM revealed the multiphase structure SiC films consisting of 3C–SiC and graphide oxide embedded in amorphous matrix. FTIR spectroscopy analysis show an increase in Si–C, Si–H, and C–H bond densities and decrease in hydrogen content with increase in TFil. The C–H bond density was found higher than the of Si–H and Si–C bond densities suggesting that H preferably get attached to C than Si. AFM investigations show decrease in rms surface roughness and grain size with increase in TFil. SEM studies show that films deposited at low TFil has spherulites-like morphology while at high TFil has cauliflower-like structure. Band gap values ETauc and E04 increases from 1.76 to 2.10 eV and from 1.80 to 2.21 eV respectively, when TFil was increased from 1500 to 2000 °C. These result show increase in band tail width (E04–ETauc) of multiphase SiC films. Electrical properties revealed that σDark increases from ~7.87 × 10−10 to 1.54 × 10−5 S/cm and Eact decreases from 0.67 to 0.41 eV, which implies possible increase in unintentional doping of oxygen or nitrogen due to improved crystallinity and Si–C bond density with increase in TFil. The deposition rate for the films was found moderately high (21

Here, a simple, controlled and cost effective electrodeposition technique was used to synthesize α-Fe2O3 hematite photo-electrode for solar water splitting. We have synthesized thin films of α-Fe2O3 by varying electrodeposition potential from −0.2 to 0 V at optimum conditions of cycles by using potentiostat. The obtained ferrihydrite thin films were transformed into α-Fe2O3 thin films by annealing them at 600 °C for 1 h. Films were investigated by XRD, SEM, UV-Visible and Raman spectroscopy for their structural, optical and morphological properties. Further suitability of α-Fe2O3 thin films as a photo-electrode has been evaluated by photoelectrochemical (PEC) measurements which exhibited photocurrent density of 65 µA/cm2 at 0.5 V versus SCE under AM 1.5 100 mW/cm2 illumination. The effective enhancement in photocurrent conversion efficiency with optimum film thickness has been observed upon light irradiation. The absorption spectrum of the α-Fe2O3 shows significant absorption in the visible region. However, photo-conversion efficiency is quite low. The obtained results suggest that the well controlled thick α-Fe2O3 material can be utilized as a shell layer with wide band gap nano-structured semiconductor like ZnO, TiO2 to form hetero-structure for solar water splitting application.

We have successfully synthesized ZnO NRs and ZnO/CdS core-shell structures by a facile two step chemical routes viz. electrodeposition and chemical bath deposition. Plane ZnO nanorods films were deposited by using three electrode electrodeposition on FTO glass substrates. The ZnO/CdS core-shell structures were deposited by immersing plane ZnO nanorod films into a bath containing precursor solution of CdS in chemical bath deposition. Formation of ZnO NRs and ZnO/CdS core-shell structures has been confirmed by UV-Visible absorption, Raman spectroscopy and scanning electron microscopy. The synthesized ZnO NRs and ZnO/CdS core-shell structures has been also characterized for photoelectrochemical (PEC) properties, Mott-Schottky analysis, electrochemical impedance spectroscopy (EIS) and efficiency measurements of PEC system. It has been found that the photocurrent conversion efficiency in water splitting is higher for ZnO/CdS core-shell photoanode than ZnO NRs photoanode. These results suggest that addition of CdS with ZnO NRs is beneficial in increasing the visible light absorption and to enhance the photocurrent conversion efficiency in water splitting. Thus, ZnO/CdS core-shell configuration can be a prospective candidate for efficient PEC splitting of water.

Photoelectrochemical splitting of water with nanocrystalline Zn 1− x Mn x O thin films was investigated. ZnO thin films with 1, 3, 5 and 7% at. Mn incorporation were synthesized by sol–gel method and characterized by X-Ray Diffraction (XRD) analysis, Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), X-ray Photoelectron spectroscopy (XPS), High Resolution Transmission Electron Microscopy (HR-TEM) and UV–Vis spectroscopy. Mn incorporation coupled with variation in sintering temperature led to significant microstructural changes, which tentatively influenced the magnitude of optical absorption and charge carrier mobility, thereby impacting the performance of such systems towards photoelectrochemical splitting of water. Electronic structure computations based on first principle density functional theory (DFT) revealed electronic states of Mn being responsible for the marginally recorded red shift in bandgap energy. Photoelectrochemical measurements using thin films of 1% at. Mn:ZnO sintered at 600 °C yielded 3 times enhanced photocurrent at zero bias due to improved optical absorption. Plausible explanations for the effect have also been offered.

Thin films of nanocrystalline Zn 1− x Ru x O 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.

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 (AFM) 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 × 1012 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.

Nanocrystalline thin films of Zn 1− x M x O (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 2 h 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 150 W Xenon Arc light source and aqueous solution of NaOH (0.01 M). 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.

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.

We use a combination of experiments and first-principles density functional theory based calculations in a study of the photoelectrochemical properties of Fe-doped BaTiO3 nanopowder. BaTiO3 with 0....

This paper deals with a study on 120 MeV Ag9+ irradiated thin films of zinc oxide (ZnO), obtained by sol-gel – spin coating onto TCO glass plates. Films irradiated at fluence 5×1011, 3×1012, 5×1012 and 2×1013 ions cm-2, were optically characterized for band gap determination. XRD analysis revealed polytypism as both wurtzite and zincblend phases co-evolved. Scherrer’s calculations indicated grain size in nanodimensions, while SEM analysis indicated smooth surface morphology of films. Flat band potentials and donor densities were evaluated by Mott-schottky calculations. For PEC studies, thin films of ZnO were employed as working electrode in conjunction with Platinum Counter electrode, Saturated Calomel Reference electrode, 13 pH aqueous solution of NaOH as electrolyte and 150W Xenon Arc light source for illumination. A significant gain in photoelectrochemical current was recorded on SHI irradiation. The films irradiated at fluence 3×1012 ions cm-2 yielded maximum increase in photocurrent that was nearly five times compared to unirradiated samples.

Nanostructured zinc oxide thin films (ZnO) were prepared on conducting glass support (SnO2: F overlayer) via sol-gel starting from colloidal solution of zinc acetate 2-hydrate in ethanol and 2-methoxy ethanol. Films were obtained by spin coating at 1500 rpm under room conditions (temperature, 28–35°C) and were subsequently sintered in air at three different temperatures (400, 500 and 600°C). The evolution of oxide coatings under thermal treatment was studied by glancing incidence X-ray diffraction and scanning electron microscopy. Average particle size, resistivity and bandgap energy were also determined. Photoelectrochemical properties of thin films and their suitability for splitting of water were investigated. Study suggests that thin films of ZnO, sintered at 600°C are better for photoconversion than the films sintered at 400 or 500°C. Plausible explanations have been provided.

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-a-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.

Forty patients with undiagnosed pleural effusions were investigated by pleuroscopy, using a fiberoptic bronchoscope. Pleural biopsies diagnostic of tuberculosis were obtained in 17 cases, and in 12 of these tubercle bacilli were cultured from the pleural fluid. Pleural biopsy at thoracoscopy is superior to the percutaneous intercostal route and for this purpose the fiberoptic bronchoscope is preferable to the rigid thoracoscope.