Chapter 28 - Photoelectrochemical Water Splitting

Abstract

Photoelectrochemical (PEC) water splitting using sunlight represents an eco-friendly and promising technology which has generated excessive consideration for the production of renewable hydrogen. Semiconductor electrode materials as the major components in PEC water splitting cells have significant impacts on the device’s solar-to-hydrogen conversion efficiency. However, there are massive tasks that still continue for enhancing the water splitting efficiency, owing to limited light gathering, energy loss related to rapid recombination of photoinduced hole–electron pairs, as well as electrode degradation. Given the complication of the PEC water splitting processes, it is essential to incorporate the various kinds of electrocatalysts for improving PEC water splitting, which presents a difficult challenge. Various kinds of semiconductor oxide photoelectrodes (TiO2, Fe2O3, WO3, BiVO4, etc.) have been engaged for fabricating PEC devices to oxidize water and generate molecular oxygen. Hybridization of these oxides with noble metals is expected to provide the enhancement of photoelectrochemical performance. This book chapter places emphasis on the latest advancement about application of these noble metal–semiconducting oxide nanohybrids for PEC water oxidation reactions. Recent progress on various kinds of both photoelectrode nanomaterials (light absorbers) and electrocatalytic nanomaterials is reviewed, and essential aspects which govern photoelectrode behaviors, comprising light absorption, charge separation and transport, surface chemical reaction rate, and the corresponding stability are discussed.