Edge-engineering of donor-acceptor sp2-carbon-conjugated covalent organic frameworks for high-performance photocatalysts

Two-dimensional sp2-carbon-conjugated covalent organic frameworks (2D sp2c-COFs) featured with fully in-plane π conjugated skeletons and tunable optoelectronic properties are appealing in photo-to-chemical energy conversion. Nevertheless, high-performance photocatalytic performance often suffers from easy carrier recombination and large band gaps. Herein, we reported the synthesis of a benzobisoxazole-linked donor-acceptor (D-A) 2D sp2c-COF (COF-TNOB-P2) via end-capping strategy to facilitate the carrier separation and migration as well as broaden the energy-harvesting capability. Due to the edge-engineered D-A structures, the COF-TNOB-P2 as the photoelectrode presents an excellent photocurrent density up to ∼88 μA cm-2 at 0 V vs. reversible hydrogen electrode, much higher than that of pristine COF-TNOB (56 μA cm-2). Moreover, the photocatalytic hydrogen evolution performance is enhanced from 1028 to 1824 μmol h-1 g-1. Our work highlights the construction of D-A 2D sp2c-COF via lattice edge functionalization methodology for high-performance photocatalysts.