Side-chain engineering of quinone-amine polymers for high-efficiency H2O2 photosynthesis

Beyond efficient charge separation, the overall efficiency of H 2 O 2 photosynthesis from water and O 2 is also limited by the kinetic mismatch between the water oxidation reaction (WOR) and the oxygen reduction reaction (ORR), which leads to an insufficient proton supply and low electron transfer density. To overcome this limitation, we incorporated proton-reservoir motifs into quinone-amine polymer (QAP)-based photocatalysts, thereby alleviating the kinetic imbalance between the two half-reactions. This approach suppressed the formation of superoxide (O 2 •− ) intermediates and facilitated the direct two-electron pathway for H 2 O 2 synthesis. Our results demonstrate that hydroquinone units and specific side-chain groups, such as hydroxyl, methoxy, and methyl, play a critical role in determining the photocatalytic H 2 O 2 production performance. Notably, the hydroxyl‑functionalized QAP exhibited a 5.3-fold higher H 2 O 2 production rate compared to its methyl-substituted analogue. Moreover, under an air atmosphere rather than pure O 2 , the hydroxyl‑modified QAP maintained high H 2 O 2 productivity with no significant decline, indicating efficient utilization of low-concentration O 2 . This robustness under ambient conditions enables continuous H 2 O 2 production without the need for external gas input. Our work underscores the significance of dual proton–electron regulation in enhancing the efficiency of photocatalytic H 2 O 2 synthesis.