Enhancing Solar-to-Hydrogen Peroxide Conversion Efficiency by Promoting the Two-Electron Water Oxidation Pathway via...

Photosynthetic hydrogen peroxide (H₂O₂) production involves coupling oxygen reduction and water oxidation half-reactions. However, the low efficiency of water oxidation constrains the overall solar-to-hydrogen peroxide conversion efficiency under natural conditions. The two-electron water oxidation pathway holds potential for enhanced photocatalytic H₂O₂ synthesis, yet its regulatory mechanisms and detailed understanding remain inadequately explored. Herein, we construct donor-acceptor (D-A) conjugated polymers with pyrene as the electron donor and triazine as the electron acceptor. By optimizing the connecting positions of the electron acceptors at the 2,7 positions of the electron donors, the main excited state is regulated from S₁ to S₂, leading to the electron transition from the lower HOMO-1 orbital. This modulation effectively enhances the oxidation capacity of the photocatalyst, enabling it to undergo two-electron water oxidation reaction (2e^- WOR) for H₂O₂ production. Consequently, the WOR activity reaches a remarkable efficiency of 2560 µmol g^-1 h^-1, corresponding to a solar-to-chemical conversion (SCC) efficiency of up to 0.94%. This strategy of modulating electronic transition orbitals to enhance the water oxidation capacity of the material significantly improves photocatalytic performance and facilitates its application in natural environments.