Covalent Polyoxomolybdate‐Organic Polymer for Direct Photocatalytic Synthesis of Hydrogen Peroxide Under O ₂ ‐Deficient Conditions

Direct photosynthesis of H 2 O 2 under O 2 ‐deficient conditions offers a clean and robust route for sustainable H 2 O 2 production. The key challenge lies in achieving a highly efficient 4 e − water oxidation reaction (WOR) to alleviate O 2 mass‐transfer limitations. Here, we report a covalent polyoxometalate‐organic polymer photocatalyst, M‐POF‐3, constructed from polyoxomolybdate (tris‐CoMo 6 ) and β ‐ketoenamine (TDOEB). It achieves a specific activity of 305.17 µmol m −2 h −1 , exhibiting one to two orders of magnitude higher than reported photocatalysts. Mechanistic studies reveal that M‐POF‐3 enables a 4 e − WOR on tris‐CoMo 6 with an ultralow overpotential. The O 2 generated during WOR can subsequently undergo short‐range internal diffusion to organic linkers for 2 e − oxygen reduction reaction. Moreover, the covalent inorganic‐organic junction in M‐POF‐3 facilitates photogenerated charge separation, further improving photocatalytic activity and cycling stability. This work integrates the advantages of polyoxometalates and organic polymers, providing a model for the design of high‐performance overall H 2 O 2 photocatalysts under O 2 ‐deficient conditions.