Heterointerface Engineering of In₂S₃/Ag₂S S‐Scheme Photocatalyst Toward Solar Hydrogen Peroxide Photosynthesis

Photocatalytic hydrogen peroxide (H 2 O 2 ) production offers a sustainable alternative to the energy‐intensive anthraquinone process. However, developing efficient semiconductor systems for oxygen reduction to H 2 O 2 remains challenging. Herein, we construct an In 2 S 3 /Ag 2 S heterostructure via a cation‐exchange strategy, achieving atomic‐level interfacial modulation that enhances charge separation and boosts H 2 O 2 production. Spectroscopic and radical trapping experiments identify the dominant active species and confirm a favorable two‐electron oxygen reduction pathway. The tailored energy band alignment between In 2 S 3 and Ag 2 S promotes visible‐light absorption and facilitates efficient carrier migration, leading to significantly improved photocatalytic performance. This work provides a feasible approach to designing transition metal chalcogenides (TMCs)‐based heterostructures for sustainable H 2 O 2 synthesis and advances solar‐to‐chemical energy conversion.