ZnIn2S4-based photocatalysts for efficient photocatalytic H2O2 production: Mechanisms, modification strategies, and future perspectives

Photocatalytic hydrogen peroxide (H 2 O 2 ) synthesis from H 2 O and O 2 driven by renewable solar energy shows great potential as a sustainable alternative to the conventional energy-intensive anthraquinone process. The overall photocatalytic efficiency is mainly governed by the light harvesting capacity, charge separation efficiency, and surface reaction kinetics of the semiconductor photocatalyst. As a representative layered ternary metal chalcogenide, zinc indium sulfide (ZnIn 2 S 4 ) has achieved extensive research progress in the photocatalysis field due to its suitable visible-light response, highly tailorable electronic structure, and unique physicochemical properties. In recent years, ZnIn 2 S 4 has also attracted rapidly growing interest in photocatalytic H 2 O 2 production owing to its sufficiently negative conduction band position, yet a systematic and in-depth review dedicated specifically to this research area remains absent. This review mainly describes recent advances in ZnIn 2 S 4 -based photocatalysts for efficient H 2 O 2 generation. The fundamental crystal and electronic structural characteristics governing the intrinsic photocatalytic activity of ZnIn 2 S 4 , the intrinsic reaction mechanisms including the dominant two-electron oxygen reduction pathway, the thermodynamically constrained water oxidation pathway, the synergistic dual-channel generation mechanism, and the non-negligible H 2 O 2 decomposition process, as well as three mainstream performance-enhancing strategies of doping engineering, surface modification, and heterojunction construction, are systematically summarized. The corresponding regulatory mechanisms for light absorption enhancement, charge carrier separation and migration, and surface reaction optimization are elucidated in depth. Finally, the remaining challenges and future development perspectives for ZnIn 2 S 4 -based photocatalytic H 2 O 2 production systems are prospected.