Covalent triazine-based frameworks confining cobalt single atoms for photocatalytic CO2 reduction and hydrogen production

Single-atom catalysts (SACs) have emerged as an advanced frontier in heterogeneous catalysis due to their potential to maximize the atomic efficiency. Herein, covalent triazine-based frameworks (CTFs) confining cobalt single atoms (Co-SA/CTF) photocatalysts have been synthesized and used for efficient CO2 reduction and hydrogen production under visible light irradiation. The resulted Co-SA/CTF demonstrate excellent photocatalytic activity, with the CO and H2 evolution rates reaching 1665.74 µmol g−1 h−1 and 1293.18 µmol g−1 h−1, respectively, far surpassing those of Co nanoparticles anchored CTF and pure CTF. A variety of instrumental analyses collectively indicated that Co single atoms sites served as the reaction center for activating the adsorbed CO2 molecules, which significantly improved the CO2 reduction performance. Additionally, the introduction of Co single atoms could accelerate the separation/transfer of photogenerated charge carriers, thus boosting the photocatalytic performance. This study envisions a novel strategy for designing efficient photocatalysts for energy conversion and showcases the application of CTFs as attractive support for confining metal single atoms.