Recent Advances on Small Band Gap Semiconductor Materials (≤2.1 eV) for Solar Water Splitting

Abstract

The conversion of solar energy into renewable H2 fuel via photoelectrochemical and photocatalytic water splitting approaches has attracted considerable attention due to its potential to solve significant energy and environmental issues. To achieve reasonable energy conversion efficiency of 10%, which is amenable to the economic feasibility of this technology, semiconductor materials, which are the main carrier for solar H2 production, must fulfill several important criteria. One of the most important criteria is the band gap of the semiconductor material, which should be low enough to allow the efficient absorption of incident light. This is because the band gap of semiconductor material fundamentally determines the upper limit of the theoretical energy conversion efficiency of the solar conversion system. In this work, recent advances in utilizing semiconductor material with a band gap smaller than 2.1 eV instead of the simply-defined visible-light-responsive semiconductor materials toward solar H2 production from water splitting was reviewed.