Molecular Fusion in Covalent Organic Frameworks Promotes Oxygen Reduction and Water Oxidation for Efficient Photocatalytic H 2 O 2 Production

Abstract

Covalent organic frameworks (COFs) have attracted much attention as photocatalysts for efficient hydrogen peroxide (H 2 O 2 ) production. Herein, we propose a molecular fusion strategy to extend planar conjugated structures to significantly enhance H 2 O 2 production performance from O 2 and H 2 O. We synthesized BTS-COF and BTT-COF using 5,5',5''-(benzene-1,3,5-triyl)tris(thiophene-2carbaldehyde) and benzo [1,2-b:3,4-b':5,6-b'']trithiophene-2,5,8-tricarbaldehyde as building blocks.BTT-COF exhibits excellent photocatalytic performance with the H 2 O 2 production rate of 2904 μmol g -1 h -1 , which is higher than that of BTS-COF (1786 μmol g -1 h -1 ). Experimental and theoretical investigations show that the fused ring structure in BTT-COF can greatly enhance the photoexcited charge transfer and change the local electronic structure. BTT-COF adopts the Pauling type for oxygen adsorption, which has lower adsorption energy. Unexpectedly, the water oxidation reaction (WOR) process of BTS-COF adopts a 4e -pathway. The WOR process of BTT-COF was transformed from 4e -to 2e -, thus improving the atom utilization efficiency and enhancing the photocatalytic H 2 O 2 production performance. In addition, the antipathogenic concentration of H 2 O 2 produced by BTT-COF at minimum inhibitory concentrations (MICs) can kill E. coli and S. aureus (100 μg mL -1 ) by destroying the bacterial membranes, making BTT-COF strong candidate as novel nano-based antimicrobial materials. This work provides valuable insights into the design and synthesis of efficient COF-based photocatalysts, and broadens the application of COFs in the antibacterial field, providing new strategies for the developing advanced anti-infective materials in the future.