Persistent semiquinone radicals enable efficient near-infrared-driven H2O2 photosynthesis

Photosynthesis of H2O2 under sunlight is a sustainable method; however, most developed photocatalysts utilize limited near-infrared light, which accounts for 52% of the solar spectrum. In typical near-infrared photocatalysts, excited electrons fall into low-energy sub-gap states, reducing the driving force for H2O2 generation. Here, a polydopamine-loaded porphyrin supramolecular photocatalyst efficiently utilizes near-infrared light for H2O2 production from H2O and O2, achieving an apparent quantum yield of 2.8% at 1020 nm. This substantial near-infrared utilization significantly boosts activity under full-spectrum irradiation, with an H2O2 generation rate of 3.37 mM/h and solar-to-chemical conversion efficiency of 2.2%. Persistent semiquinone radicals in polydopamine are demonstrated to enable ultrafast sub-gap electron transfer (ca. 79 fs) from porphyrin to polydopamine and facilitate near-infrared-driven •OOH radical generation, thereby accelerating H2O2 production. This study sheds light on the potential of near-infrared-responsive photocatalysts and offers insights into optimizing their performance for sustainable H2O2 synthesis. A porphyrin-polydopamine photocatalyst enables efficient near-infrared light use for hydrogen peroxide production from water and oxygen, achieving high quantum efficiency and solar conversion through ultrafast electron transfer mediated by persistent radicals.