Localized Oxygen Enrichment in a Covalent Organic Framework–ZnIn<sub>2</sub>S<sub>4</sub> S-Scheme Heterojunction Enables Spatially Confined Oxygen Reduction and Boosts Photocatalytic H<sub>2</sub>O<sub>2</sub> Selectivity
Minghua Xu, Xiaowen Ruan, Xinlei Zhang, Jiaqi Guo, Chunsheng Ding, Dongxu Jiao, Depeng Meng, Guozhen Fang, Jing Leng, Kaikai Ba, Tengfeng Xie, Wei Zhang, Sai Kishore Ravi, Enquan Jin, Xiaoqiang Cui
Abstract
Hydrogen peroxide is essential for green synthesis, disinfection, and energy storage, but its production remains reliant on the energy-intensive anthraquinone process, prompting the need for sustainable photocatalytic alternatives. A key challenge in artificial H 2 O 2 photosynthesis is achieving high selectivity in the two-electron oxygen reduction reaction while enhancing the reactant transport and charge separation efficiency. Herein, we design a S-scheme heterojunction integrating a sp 2 carbon-conjugated covalent organic framework (CC-COF) and ZnIn 2 S 4 (ZIS) that enables localized oxygen enrichment and spatially confined oxygen reduction reaction sites, favoring selective H 2 O 2 production. The CC-COF structure provides accessible oxygen adsorption sites, while ZIS nanosheets facilitate hydrophilic transport pathways and efficient charge separation. As a result, the heterojunction achieves a H 2 O 2 production rate of 53.6 μmol g –1 min –1 with a high selectivity of ∼70%. This work provides a rational design strategy for optimizing reactant transport and charge flow in H 2 O 2 photosynthesis, contributing to the development of sustainable solar-driven H 2 O 2 production.