Interface Engineering to Boost WO₃ Quantum Dots/g-C₃N₄ S-Scheme Heterojunctions for Photocatalytic Overall Water Splitting

Photocatalysis is regarded as a promising strategy to address global energy and environmental challenges. Therein, S-scheme heterojunctions composed of complementary semiconductors can significantly enhance the utilization efficiency of photogenerated charge carriers while preserving the inherent strong redox capabilities of the semiconductors. However, the inadequate interfacial contact between the host and guest semiconductors hinders the enhancement of carrier separation efficiency. Herein, we developed a facile route to obtain uniform dispersion of WO 3 quantum dots (QDs) on g-C 3 N 4 . Specifically, the interfacial W-N bonding tightened the connection between WO 3 and g-C 3 N 4 , which serves as an efficient pathway for electron transfer, and significantly accelerates the directional migration of charge carriers following S-scheme. The optimized WO 3 QDs/g-C 3 N 4 S-scheme heterojunction exhibits a remarkable hydrogen evolution rate of 11,097.3 μmol·g⁻¹·h⁻¹ under simulate solar irradiation. Notably, the catalyst enables prominently overall water splitting without adding sacrificial agent, achieving simultaneous evolution of stoichiometric hydrogen and oxygen, 254.5 and 125.8 μmol·g⁻¹·h⁻¹, respectively, which are 5.2 times higher than those of WO 3 NPs/g-C 3 N 4 . Even without deposition of Pt as the co-catalyst, WO 3 QDs/g-C 3 N 4 displays noticeable gas production from water. This work will provide an idea for design and preparation of efficient photocatalyst.