Optimizing interfacial S-Ag-Se bonds in Ag-In2S3@In2Se3 photoanode as “fast channels” to enhance charge transfer efficiency for boosting photoelectrochemical water oxidation

The high charge separation and transfer resistance and poor carrier utilization efficiency of In2S3-based heterojunction limit their application in photoelectrochemical (PEC) water oxidation. Herein, to reduce the disorder structure in the contact interface of In2S3-based heterojunction, Ag-In2S3@In2Se3 photoanode was prepared through a two-step method of first hydrothermal reaction followed by chemical vapor deposition (CVD). In Ag-In2S3@In2Se3 photoanode, the introduction of Selenium (Se) elements effectively alleviated the lattice mismatch, and the surface defects induced by Sliver (Ag) doping promoted the coordination of Se atoms with metal sites of Indium (In) and Ag. The shared ligands of In and Ag atoms tune interface atomic arrangement, while the S-Ag-Se bonds act as “fast channels” to reduce the charge separation and transfer resistance and improve the carrier utilization efficiency. At 1.23 V vs. RHE, the photocurrent density of Ag-In2S3@In2Se3 heterojunction photoanode is 1.03 mA cm−2 (without the aid of cocatalyst), ηsurface is 78.55 %, which are 74.28 and 5.22 times higher than of that of pristine In2S3 photoanode respectively. The optimization of charge separation resistance and enhancement of carrier charge transfer efficiency account for the improved PEC water oxidation reaction over Ag-In2S3@In2Se3 photoanode.