Bioinspired Quinone Redox Cycling Enables Highly Selective Photocatalytic Hydrogen Peroxide Production via Electron–Proton Relay

Abstract

ABSTRACT Solar‐driven synthesis of hydrogen peroxide (H 2 O 2 ) is an attractive alternative to the anthraquinone process, yet its practical viability is hindered by poor selectivity and rapid charge recombination. Inspired by quinone‐mediated charge management in natural photosynthesis, we design a conjugated polymer, DB‐TABQ, embedding redox‐active benzoquinone units that drive a light‐triggered electron‐proton relay catalysis, thereby enabling selective and efficient H 2 O 2 production. Upon photoexcitation, the benzoquinone moieties undergo proton‐coupled electron transfer to form hydroquinone intermediates that store reducing equivalents as long‐lived radical reservoirs. Subsequently, these hydroquinone intermediates adsorb and activate oxygen and initiate an inner‐sphere, concerted two‐electron transfer to produce H 2 O 2 while regenerating the benzoquinone moieties. Spectroscopic characterizations and computational investigations show that this redox‐state transformation decouples light absorption from interfacial reaction, promotes directional charge separation, enhances oxygen adsorption, and enables a selective two‐electron oxygen reduction pathway, resulting in over 95% selectivity for H 2 O 2 production. Notably, DB‐TABQ achieves a solar‐to‐chemical conversion efficiency of 1.34% under simulated solar irradiation. Embedding redox relays into conjugated polymer frameworks offers a general design principle to regulate electron‐proton coupling and selectivity in solar‐to‐chemical conversion.