Liquid–liquid interfacial approach for the facile synthesis of Tp–NBD COFs for efficient photocatalytic hydrogen production

Abstract

The preparation of highly crystalline covalent organic frameworks (COFs) is crucial for the photocatalytic hydrogen (H₂) evolution reaction (HER). However, it remains challenging because of the complicated structure of the monomer and the weakened interlayer interaction due to the large voids in the framework. Herein, a liquid–liquid interfacial (LLI) synthesis method was adopted for the spontaneous synthesis of Tp–NBD COFs at room temperature. The highly crystalline Tp–NBD COFs prepared under optimized conditions not only showed a uniformly distributed pore size of 0.6 nm and a BET specific surface area of 677.5 m² g⁻¹ but also exhibited enhanced the light absorption and promoted the charge separation. All these contributed to the photocatalytic HER activity of 21 mmol g⁻¹ h⁻¹ under AM 1.5 G irradiation, which was 24.4 times higher than that exhibited by the COF prepared by traditional solvothermal method, and it was remarkable among the pristine Tp COFs. The LLI method is expected to be extended for preparing COFs with functional groups for further enhancements in photocatalytic activities.