Key modification strategies for the rational design of hematite to promote photoelectrochemical water oxidation: a review of recent advances

Abstract

Photoelectrochemical (PEC) water splitting is a useful method for converting solar energy into H₂ and O₂, which is separated in space. Hematite (α-Fe₂O₃) is a potential photoanode water oxidation material due to its suitable band gap position, high natural abundance, low cost, nontoxicity and high chemical stability. However, inherent drawbacks including poor electronic conductivity, small diffusion length for holes (2–4 nm), limited charge carrier lifetime and sluggish kinetics are obstacles to the PEC performance of hematite. To rectify these adverse characteristics of α-Fe₂O₃, diverse strategies have been implemented. In order to provide reference and insight for researchers to quickly seek out further modification strategies, multiple modification strategies for hematite, including controlling the morphology, heterojunction engineering, doping engineering, modification of the co-catalyst and other modifications, are proposed in this review. Thereafter, the last decade of development and accomplishments of the unbiased system in hematite photoelectrodes are clarified and summarized. The article concludes with an outlook on the future prospects of hematite-based photoanodes.