Hierarchical Regulation to Design and Construct High Efficient Phenazine‐Linked COFs for Photosynthesis H₂O₂ from Water and O₂ or Air

The conjugated organic frameworks (COFs) as photocatalysts for hydrogen peroxide (H 2 O 2 ) photosynthesis are currently a hot research topic in the field of energy photocatalysis. In this work, three highly conjugated phenazine‐linked porous materials (AZA‐CMP, C 4 N‐CMP, COF‐C 4 N) and the metal anchored single atom catalysts (SACs, M‐COF‐C 4 N) are prepared based on a hierarchical regulation strategy. The research results indicate that the H 2 O 2 yield improves step by step through first adjusting the energy level by changing the pore size and CN ratio, second improving crystallinity and nanosheet morphology, and finally conducting SACs by anchoring metal ion active sites. The H 2 O 2 yield under O 2 (air) atmosphere and deionized water increases from 2770 (2070) to 6979 (6398) µmol g −1 h −1 . Further theoretical calculations and experimental researches are combined to reveal the catalytic mechanism. A dual‐pathway mechanism of synergistic two‐step 2e − ORR (oxygen reduction reaction) and one‐step 2e − WOR (water oxidation reaction) is proposed. Co‐COF‐C 4 N displays optimal photosynthesis activity of H 2 O 2 production because the N═C─C═N side‐cage can coordinate Co(II) to increase single atom active sites for ORR and at the same time Co(II) sites can promote photogenerated charge separation and transfer. This hierarchical regulation strategy provides a new insight for the design and preparation of efficient photosynthetic H 2 O 2 catalysts.