Benzotrifuran-based donor-acceptor covalent organic frameworks for enhanced photocatalytic hydrogen generation

Abstract

Visible-light-driven hydrogen evolution from water represents a green and sustainable technology to convert solar energy into chemical energy. Covalent organic frameworks (COFs) are the most competitive platforms among the variety of photocatalysts. Herein, a novel benzotrifuran-based donor-acceptor material (COF-JLU42) was constructed using a Schiff base polycondensation reaction by introducing electron-rich benzotrifuran and deficient triazine moieties into the framework. The new COF features high crystallinity and permanent porosity with a large surface area and proves to be a photoactive semiconductor with efficient visible-light harvesting capacity. Importantly, COF-JLU42 exhibits a superior photocatalytic activity with a hydrogen evolution rate of over 40 000 mu mol g-1 h-1 under visible-light illumination, which is 2.5 times higher than that of the isomorphic benzotrithiophene-based COFs under the same conditions. These findings suggest the huge application prospect of benzotrifuran-based framework materials as metal-free and solid photocatalysts in solar-energy conversion and storage. A novel benzotrifuranyl COF with excellent photovoltaic properties and low exciton binding energy was successfully constructed and used for efficient photolysis of water.