Modulating Active Hydrogen Supply and O2 Adsorption: Sulfur Vacancy Matters for Boosting H2O2 Photosynthesis Performance

Abstract

Photocatalytic two-electron oxygen reduction reaction (2e− ORR) represents a promising approach for H2O2 production. However, the lack of photocatalysts with appropriate O2 adsorption and hydrogenation capabilities impedes the H2O2 production performance. Herein, we report the synthesis of Ni-doped ZnS hollow nanocubes with S vacancies (Ni-ZnS-Sv) as a dual-site 2e− ORR photocatalyst for efficient H2O2 production. Experimental results and density functional theory calculations reveal the vital roles of Sv in modulating the electronic structures of Ni and S dual sites toward enhanced 2e− ORR selectivity and activity. The atomically dispersed Ni sites with electron-rich state enable a Pauling-type (end-on) O2 adsorption configuration and a modest binding strength of O2 and OOH*, largely avoiding the O─O bond cleavage. Besides, the formation of electron-deficient S sites weakens the S─Hads bond, facilitating *Hads migration to adjacent Ni sites and accelerating the hydrogenation kinetics of O2 to OOH* intermediate. As a result, the elaborately designed Ni-ZnS-Sv photocatalyst exhibits a high H2O2 yield of 5649.49 µmol g−1 h−1 under UV–vis light irradiation in pure water. Our work offers new insights into the design principles of high-performance photocatalysts for artificial H2O2 photosynthesis systems.