Benzothiadiazole-based donor–acceptor covalent organic framework for photocatalytic hydrogen generation†

Visible light-driven water splitting to produce hydrogen (H₂) is a promising strategy for harnessing renewable solar energy for the sustainable production of green fuel. Consequently, the design of materials with optimal absorption of sunlight/visible light is therefore of great importance. In this context, covalent organic frameworks (COFs), designed by rational selection of organic building blocks, represent promising semiconducting materials for photocatalytic hydrogen generation, offering a potential alternative to achieve efficient water splitting for H₂ generation. Herein, we demonstrate the use of a donor–acceptor COF (ETTA-BT) with benzothiadiazole (BT) moieties as the strong electron acceptor for efficient photocatalytic hydrogen generation. Interestingly, under visible light irradiation (λ ≥ 420 nm), the ETTA-BT COF exhibited superior photocatalytic performance with an H₂ generation rate of 890 μmol g⁻¹ h⁻¹, which is very high as compared to ETTA-TP COF without such a donor–acceptor system. The improved catalytic performance of ETTA-BT over ETTA-TP COF has been attributed to the donor–acceptor phenomenon, which facilitates improved charge separation and migration through the “push–pull” effect. This work represents a demonstration of the application of a donor–acceptor COF for efficient and sustainable photocatalytic H₂ generation.