Linker Engineering in Dibenzothiophene-S,S-Dioxide-Containing Conjugated Polymers for Photocatalytic Hydrogen Peroxide Production in Pure Water

Donor–acceptor (D–A) conjugated polymers have emerged as promising photocatalysts for hydrogen peroxide (H 2 O 2 ) production due to their unique optoelectronic properties. While extensive studies have explored the impact of D/A structures on photocatalytic H 2 O 2 production performance of conjugated polymers, the role of the linkage structure in modulating photocatalytic activity was rarely investigated. In this study, three D–A conjugated polymers, including ethylene-linked PSO-CC, imine-linked PSO-CN, and azo-linked PSO-NN, have been designed and synthesized by Suzuki coupling reaction. Remarkably, although the linkages differ by a single atom, the three polymers exhibit significantly different optoelectronic characteristics and charge transfer kinetics. It was revealed that photogenerated electrons preferentially migrated to the N sites in imine and azo linkages in PSO-CN and PSO-NN, respectively, thereby increasing photocatalytic H 2 O 2 production activity. The moderate polarized polymer PSO-CN shows excellent photocatalytic performance with an H 2 O 2 production rate of 1.43 mmol g −1 h −1 in pure water without any sacrificial agent. Theoretical investigation demonstrates that the imine linkages in PSO-CN serve as the active sites for photocatalysis. This work highlights the critical role of linkage electronic properties in modulating photocatalytic H 2 O 2 production performance for D–A conjugated polymers.