Hydrogen-bond-regulated hierarchical porous organic polymers for enhanced photocatalytic H2O2 production†
Abstract
Porous Organic Polymers (POPs) are promising photocatalyst for converting water and oxygen into H2O2. However, suboptimal diffusion and mass transfer efficiency of O2 restrict the reaction progress. In this work, the mass transfer of O2 was enhanced by synthesizing POPs with micro–meso–macro hierarchical porous structures. These internally interconnected pore structures through mesopores and macropores not only provide abundant transport channels but also offer a large specific surface area, increasing O2 surface accessibility. The adsorbed O2 is rapidly transferred to the catalytically active sites within the micropores to produce H2O2. Compared to Pda-TAPP with a completely disordered hierarchical pore structure, Dha-TAPP exhibited significantly enhanced H2O2 production activity. The introduction of strong polar hydroxyl functional groups has led to the formation of intramolecular hydrogen-bonding, generating a strong interfacial electric field that enhances the migration driving force of photogenerated electrons. This facilitates the continuous transfer of photogenerated electrons to active sites, accelerating the oxygen reduction reaction (ORR) process between O2 and electrons. The H2O2 production rate achieves a rate of 2905.1 μmol g−1 h−1, with a solar-to-chemical conversion (SCC) efficiency of 1.06% under simulated sunlight without aeration. This work provides new insights into the design of hierarchically porous POP photocatalysts for efficient photocatalytic H2O2 production.