Design and Synthesis of Trithiophene‐Based Donor‐Acceptor Covalent Organic Framework for Cocatalyst‐Free Photocatalytic Hydrogen Evolution

The development of high‐performance, noble‐metal‐free photocatalysts for the hydrogen evolution reaction (HER) is meaningful for sustainable development. While it remains a significant challenge. Herein, a novel covalent organic framework (COF), named BN‐COF, was designed by the imine condensation between the (N4, N4‐bis(4′‐amino‐[1,1′‐biphenyl]‐4‐yl)‐[1,1′‐biphenyl]−4,4′‐diamine) (NBD/N) and benzo[1,2‐b:3,4‐b′: 5,6‐b″]trithiophene‐2,5,8‐tricarbaldehyde (BTT/B) monomers, as electron donor and acceptor, respectively. The BN‐COF is synthesized facilely via a liquid–liquid interfacial (LLI) strategy. The BN‐COF shows photocatalytic HER activity of 7.8 mmol g −1 h −1 under AM 1.5 G irradiation without any cocatalysts and maintains the activity over 5 recycling reactions. This remarkable activity stems from the enhanced charge separation, driven by a stronger built‐in electric field within the donor‐acceptor structure, coupled with enhanced hydrophilicity imparted by the thiophene group. This work highlights the significant potential of rationally engineered D‐A structure and LLI synthetic strategy for developing effective noble‐metal cocatalyst‐free photocatalysts for efficient solar‐to‐chemical energy conversion.