Mo–S bridged ZnIn₂S₄/Bi₂MoO₆ S-scheme heterojunction photocatalyst for efficient H₂O₂ production

Sulfide-based photocatalysts hold promise for visible-light-driven H₂O₂ synthesis; however, the low efficiency of photogenerated charge carrier separation and migration remains a critical bottleneck limiting their overall yield. In response to this challenge, the construction of S-scheme heterojunctions represents a promising strategy to expedite charge carrier migration, enhance charge utilization, and consequently boost photocatalytic H₂O₂ production. This study successfully prepared an S-scheme ZnIn₂S₄/Bi₂MoO₆ heterojunction photocatalyst, bridged by interfacial Mo–S bonds, via a hydrothermal method. This catalyst achieved a high production rate of up to 1387 μmol·g⁻¹·h⁻¹ in the photocatalytic generation of H₂O₂. Combining in-situ spectroscopic characterization with density functional theory calculations, it was clarified that the formation of Mo–S bonds induces the construction of the S-scheme heterojunction. The synergistic effect of the interfacial built-in electric field and band alignment drives the spatial separation and directional migration of photogenerated charge carriers, as well as the dynamic evolution of the key oxygen intermediate, thereby enabling the efficient generation of H₂O₂ via the two-electron oxygen reduction reaction pathway. This work provides a novel interfacial engineering strategy and mechanistic insights for designing efficient and stable S-scheme heterojunction catalysts for the green photocatalytic synthesis of H₂O₂.