Enhancing Donor-Acceptor Interaction and Framework Stability by the Povarov Reaction for Photocatalytic H2O2 Production

Although photocatalytic hydrogen peroxide production by covalent organic frameworks (COFs) is emerging as a sustainable alternative for the traditional anthraquinone oxidation process, commonly studied COFs built on reversible imine bonds often suffer from poor operational stability. Here, we leverage the Povarov reaction to simultaneously improve the framework stability and install versatile functions, i.e., tunable donor-acceptor pairs for optimizing photocatalysis. By mixing the amine and aldehyde building blocks (each containing a triazine core), together with the styrene or 2-vinylthiophene reagent in one pot, the imine COF (Tz-COF; formed in situ) was converted into the more stable quinoline-linked analogs, featuring phenyl (PhTz-COF) or 2-thiophene (ThTz-COF) donors conjugated with the quinoline and triazine acceptors. Both PhTz-COF and ThTz-COF show better (steady) cycling catalytic performances than Tz-COF for visible light-driven H2O2 production from O-2 and pure water; with the stronger donor of thiophene, ThTz-COF achieves a production rate (2506 mu mol g(-1) h(-1)) doubling that of PhTz-COF (1210 mu mol g(-1) h(-1)). The structure-property correlation is also theoretically studied.