Dual-Acceptor Engineering in Pyrene-Based Covalent Organic Frameworks for Boosting Photocatalytic Hydrogen Evolution

The integration of electron donor (D) and acceptor (A) units into covalent organic frameworks (COFs) has received increasing interest due to its potential for efficient photocatalytic hydrogen (H2) evolution from water. Nevertheless, the advancement of D-A COFs is still constrained by the limited investigations on acceptor engineering, which enables the highly effective charge transfer pathways in COFs to deliver photoexcited electrons in a preferential orientation to enhance photocatalytic performance. Herein, two systems with D-A and D-A-A configurations based on the acceptor molecular engineering strategy are proposed to construct three distinct COFs. Specifically, TAPPy-DBTDP-COF merging one pyrene-based donor and two benzothiadiazole acceptors realized an average H2 evolution rate of 12.7 mmol h-1 g-1 under visible light, among the highest ever reported for typical D-A-type COF systems. The combination of experimental and theoretical analysis signifies the crucial role of the dual-acceptor arrangement in promoting exciton dissociation and carrier migration. These findings underscore the significant potential of D-A-A structural design, which is conducive to the efficient separation of photoexcited electrons and holes resulting in superior photocatalytic activities.