Reaction Pathways toward Sustainable Photosynthesis of Hydrogen Peroxide by Polymer Photocatalysts

Harnessing solar energy to generate hydrogen peroxide (H 2 O 2 ) from H 2 O and O 2 via artificial photosynthesis is an attractive route, as this approach only uses sunlight as the energy input. Organic polymers have emerged as a promising class of materials for solar-driven H 2 O 2 production, owing to their virtually unlimited molecular building blocks and rich bond-forming reactions. This distinctive feature leads to the existence of different reaction pathways characterized by different electron transfer numbers. For the overall photosynthesis of H 2 O 2, the O 2 reduction reaction and the H 2 O oxidation reaction must occur concurrently. Thus, in-depth insights into these reaction pathways are crucial for solar-driven H 2 O 2 production, with the eventual aim of steering these pathways to optimize efficiency. In this perspective, we primarily focus on the state-of-the-art progress in developing polymer photocatalysts for the overall photosynthesis of H 2 O 2 via coupling different O 2 reduction and H 2 O oxidation reactions. We also present key challenges and opportunities in developing polymer photocatalysts for H 2 O 2 production in the future. Organic polymers offer an ample molecular-level design space. They have now found extensive applications in solar-driven photochemical reactions. Therefore, this perspective serves as a guideline for designing polymer photocatalysts toward sustainable photosynthesis of H 2 O 2 and has significant implications for the future development of polymer materials in the broad area of solar-to-chemical energy conversion research.