Optimizing hematite nanostructures for electrochemical and photoelectrochemical water splitting applications

Abstract

Photoelectrochemical (PEC) water splitting using solar energy to produce renewable chemicals and fuels is a great alternative to energy crisis. However, cost-effective hydrogen production through PEC water splitting is limited by the availability of the desired semiconductor photoanode materials. Hematite photoanode (HA) fits proper for this due to its large abundance in nature, low cost, appropriate band-gap energy, and high chemical and photochemical stability. In spite of all these merits, a practical water splitting efficiency is limited due to certain limitations associated with HA including short-hole diffusion length, high recombination rate of charge carriers, and sluggish kinetics. Several modifications in HA materials has been reported in the last decade. This article comprises recent developments toward optimizing HA for PEC water splitting such as through doping, surface modification with co-catalysts, and formation of heterojunctions. Finally, the future aspects for HA to further improve its PEC water splitting efficiency is discussed.