Schiff–base nanoarchitectonics of covalent organic framework for regulation of photocatalytic hydrogen evolution: Exploration of prime factors in structural isomers

COFs have important application prospects in energy storage, chemical sensing, separation and catalytic, and photocatalyts. There are many factors affecting the photocatalytic performance of COFs, such as crystallinity, electron–hole separation efficiency and transmission speed, quantum yield, and hydrophilicity, etc. However, how to coordinate the above factors to maximize photocatalytic activity is a challenge. In this study, a pair of COFs with structural isomers were synthesized, which showed great differences in optical, electrochemical properties (fluorescence lifetime, impedance) and hydrophilicity. When ascorbic acid (AC) was used as a sacrificial agent, the hydrogen evolution rate (HER) of Py–COF–CHO was 22,977 μmol g−1 h−1, it is higher than that of Py–COF–NH2 (almost no hydrogen was detected). By systematically analyzing the relationship between optical, electrochemical, wettability and activity of structural isomers, the key factors affecting photocatalytic hydrogen production are identified: Carrier lifetime, separation, transport and material hydrophilicity. This study points out the direction for planning of COFs–based photocatalysts and provides favorable data support for the prosperity of COFs.