Enhanced hydrogen peroxide photosynthesis via charge-complementary π-electron sites.

Organic photocatalysts with porphyrin conjugated chromophore core are promising for artificial hydrogen peroxide (HO) photosynthesis, but the lack of bottom-up paradigm for oxygen (O) adsorption sites hinders their activity. Here, we introduce imidazole groups as π-electron sites with charge-complementarity to the O molecules, enhancing O binding via sub-atomically mirrored electrostatic cooperative π-π dispersion forces. In situ spectroscopy and theory reveal that the ~2 Å linear δ-δ-δ domain of the imidazole substituent exhibits 2.8-folds stronger O adsorption than neutral π-electron substituents, accompanied by the generation of energetically peroxide intermediates. Consequently, imidazole-substituted porphyrin photocatalysts achieve a solar-to-chemical conversion efficiency of 1.85% using only HO and O. In scalable membranes with photocatalysts, enabling daily photosynthetic production of 80 L m of Fenton-applicable HO solution. This work offers a strategy to modulate the electrostatic distribution of oxygen photoreduction sites, providing insights into overcoming gas activation rate-limiting steps in photocatalytic processes.