Co0.2Cd0.8S/Mn0.2Cd0.8S S-Scheme Heterojunction Promoting Directed Charge Separation and Boosting Photocatalytic Hydrogen Production

Constructing S-scheme heterojunctions is an effective strategy for enhancing photocatalytic efficiency. In this study, a Co0.2Cd0.8S/Mn0.2Cd0.8S S-scheme heterostructure was successfully prepared via a facile physical mixing method. Compared with pristine Co0.2Cd0.8S and Mn0.2Cd0.8S, the CM25 (the mass ratio of Co0.2Cd0.8S to Mn0.2Cd0.8S is 25%) composite exhibited significantly superior performance in photogenerated charge-carrier separation and reduced charge-transfer resistance. X-Ray photoelectron spectroscopy analysis confirmed the existence of an internal electric field oriented from Mn0.2Cd0.8S toward Co0.2Cd0.8S at the interface, accompanied by a redistribution of interfacial electron density. This strong interfacial coupling not only markedly facilitates the spatial separation of photogenerated carriers but also preserves their robust redox capability. Photocatalytic hydrogen evolution experiments further revealed that over a 5 h reaction period, the hydrogen production of the composite catalyst reached approximately 6.71 and 6.30 times those of pristine Co0.2Cd0.8S and Mn0.2Cd0.8S, respectively. Overall, this work provides a feasible pathway for the rational design of high-performance Cd-based photocatalysts toward solar-driven hydrogen production.