Photocatalytic Hydrogen Cycling via Benzotrithiophene-Based Mesoporous Covalent Organic Frameworks for Efficient Fine Chemical Coproduction

Solar-driven hydrogen cycling, which enables efficient coproduction of fine chemicals, holds significant importance for advancing the sustainable development of modern society. Here, we demonstrate the highly efficient coproduction of N-benzylidenebenzylamine (N-BBA) and hydrogen peroxide (H 2 O 2 ) from benzylamine and air on well-designed benzotrithiophene-based mesoporous covalent organic frameworks (BTT-COFs). Linkers with an intertwined spatial distribution of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) were carefully explored for the construction of BTT-COFs. This design inherently establishes short-range charge transfer (SRCT) states, promoting localized cooperative activation for the proposed hydrogen cycling reactions. The optimized BTT-COF exhibited exceptional photocatalytic hydrogen cycling performance, with high N-BBA and H 2 O 2 yields of approximately 20.5 and 24.4 mmol g –1 h –1, respectively, accompanied by high apparent quantum efficiencies of 9.4 and 12.6% at 450 nm. Mechanism investigations revealed that the excellent hydrogen cycling performance originated from the synergistic combination of well-designed electronic microenvironment and optimal reactant/intermediate adsorption behaviors. This work highlights the BTT-COFs as efficient photocatalysts for fine chemical coproduction, providing a molecular-level design strategy for the exploration of advanced catalysts for various photocatalytic applications.