Fabrication of a Sb2Se3/CuSbS2 Heterojunction Photocathode for Photoelectrochemical Water Splitting

Antimony selenide (Sb2Se3) is a promising semiconductor light-absorbing material for photoelectrochemical (PEC) water splitting to produce hydrogen. Effectively promoting the separation of photogenerated carriers and extracting holes from the light-absorbing layer to the back electrode are key to improving the PEC performance. In this work, the Sb2Se3/CuSbS2 heterojunction was prepared by a facile and cost-effective method that involves solution synthesis, spin-coating, and thermal treatment processes. The PEC performance of the Sb2Se3/CuSbS2 heterojunction was optimized by adjusting the drying temperature of the prepared CuSbS2 films. After surface passivation with TiOx, the Sb2Se3 surface defects were passivated and the PEC devices were well protected, and the Pt/TiOx/Sb2Se3/CuSbS2/FTO photocathode possessed a photocurrent density of 18.0 mA cm–2 at 0 V versus reversible hydrogen electrode, about four times that without the CuSbS2 layer. This excellent PEC performance benefits from the construction of heterojunctions with suitable energy band alignment and the improved electron–hole pair separation and transfer efficiency. This work provides an effective strategy and important guidelines for improving the PEC efficiency of the Sb2Se3 photocathode by introducing CuSbS2 to form a heterojunction.