Donor-acceptor conjugated polymers for the photosynthesis of H2O2 in pure water

Hydrogen peroxide (H2O2) is a critical chemical widely applied in many areas. However, its conventional industrial production through the anthraquinone process is highly energy-intensive and generates considerable toxic by-products, raising environmental and sustainability concerns. As a result, photocatalytic synthesis of H2O2 directly from water and oxygen using solar energy has emerged as a promising and sustainable alternative. In this context, donor-acceptor (D-A) conjugated polymers have recently attracted growing attention due to their easily tunable band structures and efficient charge separation characteristics. This review provides a comprehensive summary of the latest progress in the design and application of D-A conjugated polymers for sacrificial-agent-free H2O2 photosynthesis in pure water. Key aspects discussed include the molecular engineering of donor and acceptor units, the influence of linkage type and orientation, and the impact of topology modulation on charge transport dynamics. Furthermore, strategies such as active-site engineering to improve selectivity in oxygen reduction and water oxidation pathways, as well as mass transfer optimization via porous structures and hydrophilic channel design, are critically evaluated. These advances have collectively enabled significant improvements in the rate, selectivity, and stability of photocatalytic H2O2 production. Finally, the challenges that remain, such as achieving higher solar-to-chemical conversion efficiency and developing scalable synthetic routes, are outlined. Perspectives are provided on future opportunities for rational molecular design and structural optimization of D-A conjugated polymers. Overall, this review highlights the potential of D-A conjugated polymers as highly promising photocatalysts for sustainable H2O2 production, offering guidance for future research and practical applications.