Fully conjugated sp 2 carbon-linked cyano-containing D–A–A covalent organic frameworks for overall hydrogen peroxide photosynthesis

Abstract Covalent organic frameworks (COFs) have emerged as promising photocatalysts for hydrogen peroxide (H2O2) production, yet their performance is often limited by inefficient photogenerated charge separation and transport. Herein, a sp2 carbon-conjugated donor–acceptor–acceptor (D–A–A) COF (TFPT-TCPB-COF) (TFPT = 2,4,6-tris(4-formylphenyl)-1,3,5-triazine, and TCPB = 2,2'-(5'-(4-(cyanomethyl)phenyl)-[1,1':3',1''-terphenyl]-4,4''-diyl)diacetonitrile) incorporating a strong electron-withdrawing cyano group was rationally designed and synthesized via an optimized solvothermal method. The unique D–A–A architecture, together with abundant reductive active sites (triazine and cyano groups) for two-electron oxygen reduction and oxidative sites (benzene rings) for two-electron water oxidation, enables efficient H2O2 generation in pure water without sacrificial agents. As a result, TFPT-TCPB-COF achieves a high H2O2 production rate of 4.43 mmol·g−1·h−1, which is 1.72 times greater than that of its imine-linked analogue (TFPT-TAPB-COF). Additionally, it exhibits an apparent quantum yield of 12.4% at 420 nm, outperforming most reported COF-based photocatalysts. Experimental and theoretical analyses reveal that the enhanced activity originates from improved charge separation and transport, as well as a modulated electronic structure that lowers the energy barriers for key *OOH and *OH intermediates during the photocatalytic process. This work provides important molecular insights into the design of advanced COF photocatalysts with donor–acceptor architectures for efficient solar energy conversion.