A novel α-Fe2O3 photoanode with multilayered In2O3/Co–Mn nanostructure for efficient photoelectrochemical water splitting

Hematite (α-Fe2O3) is considered one of the most promising materials for PEC water splitting under solar light. However, the drawbacks of lower charge transfer efficiency and slow oxygen evolution reaction (OER) kinetics seriously limited the practical application of α-Fe2O3 photoanodes. In this work, a multilayer structure modified α-Fe2O3 photoanode is proposed. Firstly, the In2O3 nanolayers were loaded onto the surface of α-Fe2O3 nanorods, significantly increasing the photoelectrochemical (PEC) water oxidation activity. The heterojunction form by the In2O3 passivation layer with α-Fe2O3 effectively promotes charge separation. Next, an electrodeposition method deposited a nanosheet combining ultrathin non-crystalline Co(OH)x and Mn3O4 nanocrystals (Co–Mn) on the α-Fe2O3 thin film. As an efficient co-catalyst, the Co–Mn nanosheets assisted the performance of α-Fe2O3 PEC water oxidation. The optimized α-Fe2O3–In2O3–Co(OH)x-Mn3O4 photoanode produces a high photocurrent density of 6.5 mA/cm2 at 1.23 V (vs. RHE), a maximum IPCE of 57.9% at 400 nm can reach.