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.