Fabricating S-Scheme Heterojunction via D-A Type COF and ZnIn2S4 Quantum Dots: An Efficient Strategy for Photocatalytic Generation of Hydrogen Peroxide

In this study, a donor-acceptor (D-A) conjugated design strategy was used to synthesize a novel covalent organic framework (NLCOF, the COF initiated by Na Lv), using 2,5-dimethoxylterephthalaldehyde as the building block via the Kröhnke reaction. Subsequently, ZnIn 2 S 4 quantum dots (ZIS QDs) were physically combined with NLCOF for constructing a ZIS QDs-NLCOF S-scheme heterojunction composite photocatalytic system. This system achieved an H 2 O 2 production rate of 6 417 µmol·g −1 ·h −1 in pure water using the 40ZIS-NLC composite catalyst, which was 4.2 and 26.7 times higher than that of ZIS QDs and NLCOF, respectively. Upon adding 1 mL benzyl alcohol to the system, the H 2 O 2 production rate drastically increased to 53 383 µmol·g −1 ·within 5 h. Advanced characterization techniques, including XPS, KPFM, and EPR were employed to elucidate the intrinsic mechanism of S-scheme heterojunction photocatalytic H 2 O 2 production. This study offers insights into the rational design of high-performance COF-based heterojunction photocatalysts and provides a robust foundation for optimizing interfacial electron-coupling interactions to enhance overall photocatalytic efficiency.