Anjana Solanki

Photoelectrochemical performance of bilayered Fe–TiO2/Zn–Fe2O3 thin films for solar generation of hydrogen

A visible-light sensitive bilayered photoanode of Fe–TiO2/Zn–Fe2O3 has been developed by spray pyrolytically depositing Zn–Fe2O3 layers onto predeposited Fe–TiO2 thin film on ITO substrate. Fe–TiO2/Zn–Fe2O3 photoelectrodes were characterized by XRD, Raman, AFM, UV-vis absorption spectroscopy. Photoelectrochemical properties of bilayered Fe–TiO2/Zn–Fe2O3 photoelectrode were studied by Mott–Schottky curves and I–V characteristics. Bilayered Fe–TiO2/Zn–Fe2O3 photoelectrode was observed to possess much higher separation efficiency of photogenerated charge carriers and could generate nine times better photocurrent density than pure Fe–TiO2. Solar to hydrogen conversion efficiency exhibited by this electrode was 0.77%.

Enhanced Photoelectrochemical Activity of 120 MeV Ag9+ Irradiated Nanostructured Thin Films of ZnO for Solar-Hydrogen Generation via Splitting of Water

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 ZnO for photoelectrochemical splitting of water to produce hydrogen: swift heavy ion irradiation vis-à-vis dye-sensitisation

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.

PHOTOELECTROCHEMICAL WATER SPLITTING USING BILAYERED ZnO/SrTiO3 PHOTOELECTRODES

Nanostructured zinc oxide overlayered by nanoporous strontium titanate was synthesized using sol-gel method and tested in a photoelectrochemical (PEC) cell for splitting of water. It was found that compared to the pristine ZnO and SrTiO3, the resistivity of bilayered thin film was reduced and a negative shift in open circuit potential and flatband potential of bilayered ZnO/SrTiO3 was observed, thus improving the photocurrent density and photoconversion efficiency. Significantly, bilayered ZnO/SrTiO3 thin film offered the best photocurrent density i.e. 0.46 mA/cm2 at 0 V/SCE. XRD, SEM and UV-Vis spectroscopic studies were carried out to explore the structural, surface morphological and optical properties of various thin films.

A Clean and Green Hydrogen Energy Production Using Nanostructured ZnO and Fe-ZnO via Photoelectrochemical Splitting of Water

To meet tomorrow’s demand of cheap, environment friendly and renewable hydrogen, the industries must find new ways of producing it. One solution, with a high potential, is extracting hydrogen by direct splitting of water using solar energy. This study deals with photoelectrochemical splitting of water by using nanostructured ZnO and Fe-ZnO thin films as a working photoelectrode. ZnO and Fe-ZnO films were synthesized by sol-gel spin coating method and were characterized for formed crystalline phase by XRD analysis, band gap energy by spectrometric measurement and surface topography by AFM analysis. Subsequently, these were used as working electrode in PEC cell in conjunction with a platinum counter electrode, saturated calomel reference electrode and 150 W Xenon Arc Light Source for illumination, and PEC current densities were recorded, using aqueous solution of NaOH and KOH.