Recent strategies to enhance the efficiency of hematite photoanodes in photoelectrochemical water splitting

Photoelectrochemical (PEC) water splitting is one of the most promising approaches toward achieving the conversion of solar energy to hydrogen. Hematite is a widely applied photoanode material in PEC water splitting because of its appropriate band structure, non-toxicity, high stability, and low cost. Nevertheless, its relatively low photochemical conversion efficiency limits its application, and enhancing its PEC water splitting efficiency remains a challenge. Consequently, increasing efforts have been rendered toward improving the performance of hematite photoanodes. The entire PEC water splitting efficiency typically includes three parts: the photon absorption efficiency, the separation efficiency of the semiconductor bulk, and the surface injection efficiency. This review briefly discusses the recent advances in studies on hematite photoanodes for water splitting, and through the enhancement of the three above-mentioned efficiencies, the corresponding strategies toward improving the PEC performance of hematite are comprehensively discussed and summarized.