Two-Dimensional S-Scheme Engineering in Bi₂WO₆/S_V-ZnIn₂S₄ for Solar-Driven H₂O₂ Generation in Pure Water

The development of eco-friendly hydrogen peroxide (H₂O₂) synthesis through the photocatalytic oxygen reduction reaction holds significant potential for sustainable chemical engineering; however, it remains hindered by the necessity of sacrificial agents. Herein, we construct a two-dimensional (2D) S-scheme heterojunction through interfacial coupling of S-vacancy-rich ZnIn₂S₄ (S_V-ZIS) with Bi₂WO₆ (BWO) nanosheets via an in situ growth method. Band alignment engineering establishes a giant built-in electric field at the Bi₂WO₆/S_V-ZIS interface, which drives directional S-scheme charge transfer, leaving the photogenerated electrons and holes with the highest redox potentials accumulated on BWO and S_V-ZIS, respectively, for O₂ reduction and H₂O oxidation. This spatial separation mechanism enhances both electron-hole pair dissociation efficiency (validated by transient photocurrent analysis) and preserves strong redox potentials (reflected in free-radical capturing experiments). The 2D/2D architecture further amplifies interfacial charge migration through atomic-level contact, leading to an efficient H₂O₂ production rate of 822 μmol L^-1 h^-1 in pure water. This work provides a two-dimensional S-scheme engineering strategy for designing high-performance photocatalysts toward sustainable H₂O₂ synthesis under environmentally benign conditions.