Hydrogen production through Solar water splitting is the ultimate pathway for renewable and sustainable production of energy. There are two main routes for hydrogen production through solar energy; Photocatalytic and Photoelectrochemical (PEC). Photocatalytic process consists of slurry based catalyst solution where both Hydrogen and Oxygen are evolved in the same atmosphere whereas photoelectrochemical process consists of electrochemical cells with separate compartments/ electrodes for facilitating reduction and oxidation reaction for the production of hydrogen and oxygen respectively. Therefore gas separation is not required in photoelectrochemical water splitting. This is one of the chief advantage of PEC process over photocatalytic water splitting. In a techno-commercial analysis prepared by James et. al. [1], PEC water splitting can be commercially viable if an efficient photoactive material is used in a tracking concentrator type reactor. Enormous research work has been carried out in the past two decades on finding a suitable photoactive material for water splitting through photoelectrochemical route since the initial discovery reported by Honda and Fujishimha in 1972 [2]. On the top level, material research is facing two major trade-offs; one in between higher potential drive (higher bandgap) and spectral response and second in between solar to hydrogen (STH) efficiency and material stability [3]. Therefore the research is progressing in the direction to modify properties of suitable bandgap materials through various approaches like bulk modification, surface modification and nano-structuring.
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