Hydrogen-Bond Engineered Porphyrin-Polyimide Aerogels for Sustainable Photocatalytic H₂O₂ Production from Water and O₂

Hydrogen peroxide (H2O2) is a highly significant substance that is extensively utilized in numerous industrial applications and has the potential for use as an energy carrier in fuel cells. However, the conventional anthraquinone oxidation process for H2O2 production faces challenges, such as high energy consumption and environmental pollution, conflicting with global sustainability goals. The photocatalytic synthesis of H2O2 represents a promising alternative to address these limitations. Here, we report tetra(4-carboxyphenyl)porphyrin-cross-linked polyimide aerogels (PICP) as a metal-free photocatalyst for H2O2 production from H2O and O2 under solar irradiation, achieving a rate of 1.55 mM h–1 under the optimal conditions. The PICP photocatalyst exhibits a solar-to-chemical conversion (SCC) efficiency of 0.98% under solar irradiation. The results of mechanistic studies indicate that the synergistic effect of amide and hydrogen bonds in PICP facilitates the separation and utilization of photogenerated holes and electrons, enabling a direct 2e– oxygen reduction pathway that significantly enhances the H2O2 generation efficiency. Furthermore, a secondary pathway involving the photoconversion of −COOH groups to −COOOH intermediates, followed by thermal decomposition to H2O2, further improves the utilization efficiency of photogenerated carriers.