Well-Designed Spherical Covalent Organic Frameworks with an Electron-Deficient and Conjugate System for Efficient Photocatalytic Hydrogen Evolution

Photocatalytic hydrogen evolution from water is an outstanding way to convert solar energy under the photocatalytic process. Unfortunately, traditional photocatalysts can not guarantee both the avoidance of charge recombination and the acceleration of electron transfer in hydrogen evolution reaction (HER). Therefore, it is a challenge to design catalysts for low charge recombination and fast electron transfer from a molecular perspective. Herein, covalent organic frameworks (COFs) with different rings such as a boric acid ring, nitrogen heterocyclic ring, and benzene ring were synthesized for the first time by changing the molecular structure. Importantly, COFs coupled to the benzene ring with a boric acid ring not only accelerate electron transfer by the conjugated system but also avoid electronic recombination because of the electron-deficient characteristics. The optimal HER was as high as 2789.46 μmol h –1 ·g –1 . COFs are regulated at the molecular level by DFT calculation, which provides a method for the development of catalysts and analysis of the mechanism.