Interfacial Engineering of In2O3/In2S3 Heterojunction Photoanodes for Photoelectrochemical Water Oxidation

Photoelectrochemical (PEC) water splitting is one of the critical energy conversion techniques to prepare for future energy demands. Among the various trials to construct effective water splitting semiconductor photoelectrodes, In 2 O 3 /In 2 S 3 heterostructures can be promising candidates for their advantageous properties in solar water oxidation. Herein, we synthesized In 2 O 3 nanorods on FTO substrate through a direct glancing angle deposition method. Subsequently, the In 2 S 3 layer was conformally coated on In 2 O 3 nanorods through facile chemical bath deposition. As synthesized photoanodes of In 2 O 3 /In 2 S 3 form type II junction, leading to considerable cathodic onset potential shift with the increased photocurrent density compared to pristine samples. To further enhance PEC properties, the interficial engineering strategies of the Co ion doping and the deposition of ultra-thin Al 2 O 3 film were carried out. Co ion could facilitate the charge transfer in photoanodes through the increased surface area, and the 2 nm Al 2 O 3 layer coated above the photoanode effectively worked as the passivation layer to stabilize the photoanodes in alkaline electrolytes environments. This work would contribute to developing efficient photoanodes through various nanoscale engineering strategies. Graphical Abstract