Blending Strategy for D–A-Structured COF with Enhanced Photocatalytic Hydrogen Evolution

Covalent organic frameworks (COFs) have shown great potential in the field of photocatalysis. In this study, two amine monomers, 4,4’-(benzo[ c ][1,2,5]thiadiazole-4,7-diyl)dianiline (BTD) and 4,4’-(5,6-dimethyl-4,7-dihydrobenzo [c][1,2,5]thiadiazole-4,7-diyl)dianiline (CTD), with different electron-withdrawing capabilities, were selected to couple with 2,4,6-triformylphloroglucinol (Tp) to construct COFs. The 2BTD/1CTD COF synthesized by the blending strategy significantly enhanced the photocatalytic hydrogen evolution activity compared with the symmetrical two-component TpBTD and TpCTD COFs. The characterization results indicate that the 2BTD/1CTD COF with a D–A structure possesses the lowest exciton binding energy and higher photogenerated carrier separation and transport efficiency. These features collectively contribute to an enhanced charge separation efficiency. The blending strategy effectively improves the photocatalytic performance and provides an idea for designing more efficient COF photocatalysts.