Three-Dimensional Tetrathiafulvalene-Based covalent organic frameworks for efficient photocatalytic nitrogen fixation

Abstract

Preparing photocatalytic nitrogen-fixing catalysts that can effectively produce ammonia under mild conditions is an urgent problem to be solved. Herein, we for the first time present two three-dimensional tetrathiafulvalene-based covalent organic frameworks with high crystallinity and permanent pores, termed 3D-TTF-COFs, specifically designed for photocatalytic nitrogen fixation. The incorporation of TTF-based building blocks not only enhances light absorption capabilities but also facilitates the rapid transfer of photoexcited electrons, ensuring efficient charge carrier separation. It is worth noting that the resultant COFs exhibit remarkable NH3 generation rates of 313.8 ± 5.6 and 106.8 ± 4.2 μmol g−1h−1 under visible light irradiation, surpassing the performance of most photocatalyst materials reported so far. Furthermore, these COFs maintain structural integrity and excellent performance during cyclic testing. Additionally, we carried out density functional theory calculations to elucidate the reaction mechanism between N2 and NH3. This work provides a feasible strategy for constructing 3D COFs to achieve efficient photocatalytic nitrogen fixation.