Regulating photogenerated electron migration direction: A key to enhance the photoinduced cathodic protection performance of the In2S3/MgIn2S4composite and ZnIn2S4 heterojunction system

Photoinduced cathodic protection (PICP) technology exhibits substantial research significance in the field of corrosion science. This work designed and fabricated a nanocomposite-structured photoelectrode (Ti-MIS/ZIS) composed of an In₂S₃/MgIn₂S₄ composite (MIS) and ZnIn₂S₄ (ZIS) on an etched titanium sheet via a two-step hydrothermal method. The Ti-MIS/ZIS photoelectrode exhibits a significantly broadened visible-light absorption range as well as rational band alignment. The uniform anchoring of ZIS nanosheets on the Ti-MIS surface constructs a gradient band structure, and the resultant built-in electric field drives the migration of photogenerated electrons toward the conduction band of Ti-MIS, thus enabling efficient carrier separation. The rational band structure of Ti-MIS/ZIS enables abundant generation and directional migration of photogenerated electrons to the 316 L SS surface, thus realizing effective PICP. Under AM 1.5 G illumination, the Ti-MIS/ZIS photoelectrode coupled with 316 L SS achieves a photoinduced current density of 40 μA·cm⁻² and a negative shift of open-circuit potential to −0.47 V, exhibiting remarkably superior PICP performance to other photoelectrodes.Via band engineering design, this work achieves precise directional regulation of photogenerated carrier dynamics, laying a direct theoretical foundation for the development of high-efficiency heterojunction photoelectrode systems. Moreover, the revealed interfacial charge transfer mechanism exhibits universal guiding significance for heterojunction systems.