Reaction Pathways toward Sustainable Photosynthesis of Hydrogen Peroxide by Polymer Photocatalysts

Harnessing solar energy to generate hydrogen peroxide (H2O2) from H2O and O2 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 H2O2 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 H2O2, the O2 reduction reaction and the H2O oxidation reaction must occur concurrently. Thus, in-depth insights into these reaction pathways are crucial for solar-driven H2O2 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 H2O2 via coupling different O2 reduction and H2O oxidation reactions. We also present key challenges and opportunities in developing polymer photocatalysts for H2O2 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 H2O2 and has significant implications for the future development of polymer materials in the broad area of solar-to-chemical energy conversion research.