Indium sulfide-sensitized 2D stannum indium sulfide nanosheet arrays promoting photoelectrochemical conversion efficiency in cathodic protection

This study reports the fabrication of 2D stannum indium sulfide (SnIn4S8) nanosheet arrays sensitized with indium sulfide (In2S3) and their potential application as photoanodes in photoelectrochemical cathodic protection for 304 stainless steel. The deposition of In2S3 flakes on the surface of the SnIn4S8 nanosheet arrays induces a notable alteration in the optical absorption of the composite samples, showing a maximum redshift from 560 nm to 645 nm. The incorporation of In2S3 regulates the energy band structure of SnIn4S8 by pulling its Fermi level and valence band maximum towards a negative direction. The type-II heterojunction formed by sensitization with In2S3 strengthens the separation efficiency of photoinduced carriers in SnIn4S8, inhibiting self-corrosion. The particular 5%-In2S3/SnIn4S8 composite demonstrates a notable shift in the mixed potential towards negative values, reaching a potential of −1.05 V when exposed to visible light. An excessive amount of In2S3 is not conducive to the directional flow of carriers at the heterojunction interface, preventing efficient separation of electron-hole pairs. This research highlights the advantages of the In2S3-sensitized SnIn4S8 composites for photogenerated cathodic protection.