Enhanced hydrogen peroxide photosynthesis in covalent organic frameworks through induced asymmetric electron distribution

Covalent organic frameworks (COFs) can be used as photocatalysts for the direct photosynthesis of hydrogen peroxide (H₂O₂) from oxygen, water and sunlight. However, their highly symmetric structure can lead to weak adsorption of O₂ and, therefore, unsatisfactory photocatalytic performance. Here we explore the local asymmetric electron distribution induced by Pauli and electron–electron repulsion in COFs to construct localized bonding sites for O₂ species, which promotes photocatalytic H₂O₂ production. Experimental results and theoretical calculations reveal that TAPT–FTPB COFs (where TAPT is 1,3,5-tris-(4-aminophenyl) triazine and FTPB is 5-(5-formylthiophen-2-yl)thiophene-2-carbaldehyde) with an asymmetric electron distribution show strong O₂ adsorption interaction and a record-breaking solar-to-chemical conversion efficiency of 1.22% for direct photosynthesis of H₂O₂ from oxygen and water, which is higher than in the photosynthesis of plants (~0.1%). A flow-type photocatalytic microreactor integrated with TAPT–FTPB COFs exhibits 100% sterilization efficiency for killing bacteria and 97.8% conversion for photocatalytic 2-thiophene methylamine coupling. This work reports a strategy for manipulating the local electron distribution in COFs, opening the door for research on the rational design of high-performance photocatalysis with a local asymmetric electron distribution.