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

The development of eco-friendly hydrogen peroxide (H 2 O 2 ) 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 ZnIn 2 S 4 (S V -ZIS) with Bi 2 WO 6 (BWO) nanosheets via an in situ growth method. Band alignment engineering establishes a giant built-in electric field at the Bi 2 WO 6 /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 O 2 reduction and H 2 O 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 H 2 O 2 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 H 2 O 2 synthesis under environmentally benign conditions.