Nanostructured bilayered thin films in photoelectrochemical water splitting – A review

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.