Experimental and Theoretical Studies of BiVO4 and related materials for Photoelectrochemical Splitting of Water and Hydrogen Generation

Abstract

In present scenario, modernization of world in addition to depletion of fossil fuel reserves is the main cause for increased demand of energy in the form of fuel. Hydrogen is considered to be green energy fuel and can be an alternative for overcoming the hike in energy demand. Various ways can be adopted to produce hydrogen but photoelectrochemical (PEC) path is the most suitable and efficient. The photoelectrochemical method uses a working electrode made of nanostructured material which is mainly semiconductor. So, to achieve the standards for commercial application, the main area of focus is the development of semiconductor materials. newlinePresent study mainly focuses on BiVO4 and Fe2O3 semiconductor material. The properties of materials were altered and improved for PEC water splitting efficiency by homojunction formation, gradient doping and ion irradiation. For BiVO4, the ab initio calculations were performed using density functional theory (DFT) to predict its properties. Important findings of theoretical calculations are: a) the position of band edges are suitable with redox potential of water and b) Fermi level shift towards conduction band with Mn doping and oxygen vacancy. Experiment was then designed based on the results obtained from DFT calculations to make homojunction of Mn doped BiVO4 with pristine BiVO4 which showed better response over pristine. Gradient doping of Ti in Fe2O3 matrix was investigated with increased charge separation efficiency. Effect of low energy ion beam irradiation on BiVO4 was also explored for the first time with respect to PEC water splitting. newlineThin films of both the semiconductor materials were prepared by spray pyrolysis method. The physical characterization techniques adopted in this study includes X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), Secondary ion mass spectrometry (SIMS), UV-visible absorption spectroscopy, scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDX). PEC performance was analyzed by current voltage charact