Electrolyte and interfacial engineering for self-formation of In2S3/In2O3 heterojunction with an enhanced photoelectrochemical activity

Electrolyte and interfacial engineering of photoanodes has become a crucial approach to enhance photoelectrochemical water-splitting performance. By optimizing both the electrolyte and the interfacial properties of the photoanode, the synergistic effects of the heterojunction and electrolyte can be leveraged to improve efficiency. In this work, we explore the crucial role of electrolyte and interfacial engineering in optimizing photoanode performance. By engineering an In2O3 film in a polysulfide electrolyte to form an in-situ In2S3/In2O3 heterojunction interface, we demonstrate a significant increase in anodic photocurrent compared to traditional aqueous Na2SO4 or NaOH electrolytes. This enhancement is attributed to both the thermodynamically favorable oxidation of sulfide and sulfite, and the unique electronic structure developed at the In2S3/In2O3 junction, which significantly improves charge separation and overall performance. Based on this finding, an efficient In2S3/In2O3 heterojunction interface through optimal anion exchange with sulfur was developed, leading to a maximum photocurrent density of 5.57 mA cm(-2) in the polysulfide electrolyte. In addition, detailed structural, optical, and photoelectrochemical properties of the In2S3/In2O3 interface providing insights into the mechanisms underlying the enhanced water-splitting performance have also been discussed.