Near-Infrared responsive Bi2S3-sensitized WO3 S-scheme heterojunction photoelectrochemical coating for effective solar-driven cathodic protection

Solar-driven photoelectrochemical cathodic protection offers a green and sustainable strategy for marine metal corrosion prevention, requiring no additional energy input and causing no environmental pollution. However, practical deployment is limited by narrow spectral utilization and the loss of protection in the dark. Herein, we design a near-infrared light responsive Bi 2 S 3 -sensitized WO 3 S-scheme heterojunction (TWB) photoelectrode coating that integrates efficient photoelectric conversion with electron storage capability. The TWB photoelectrode exhibits an absorption edge extending to approximately 1500 nm, enabling efficient utilization of visible and near-infrared light. Under simulated solar irradiation, the TWB photoelectrode achieves a photocurrent density nearly eight times higher than that of pure WO 3 . When coupled with metal, the composite photoelectrode provides sustained cathodic protection in the dark, deriving from the electron-storage characteristic of WO 3 . Combined DFT calculations, in-situ XPS, and ESR analyses confirm the S-scheme charge transfer mechanism, which achieves efficient charge separation and transport while preserving highly reductive electrons in Bi 2 S 3 for effective cathodic protection. This work provides a simple and operable strategy for designing wide-spectrum responsive and energy-storing photoelectrodes that advance green and sustainable corrosion protection for marine installations.