Anchoring cobalt single atoms on 2D covalent triazine framework with charge nanospatial separation for enhanced photocatalytic pollution degradation

Covalent triazine frameworks (CTFs) show great potential in photocatalytic fields, while their practical efficiency is still limited due to rapid charge recombination. Here we report a nanospatial separation strategy for photoinduced electron-hole pairs of CTF-1 nanosheets via single-atom Co using facile pyrolysis and phosphorization to form stable Co-N-3 (approximate to 1.60 angstrom) architecture. HAADF-STEM image demonstrates Co atoms are uniformly dispersed onto ultrathin CTF-1. The local structure surrounding and chemical valent state of Co are systematically investigated by Fourier-transformed EXAFS and K-edge XANES, respectively. Co single atoms as oxidation centers can capture holes transferred from CTF-1, thus resulting in narrow bandgap and improved photo-exciton dissociation in the two-dimensional (2D) direction. The obtained Co/CTF-1 exhibits excellent efficiency of 99.9% for pollutant photodegradation, far outperforming that of pristine CTF-1 (68.8%). Nanospatial separation endows Co/CTF-1 with various micropollution removal capabilities, outstanding cyclic stability, and a widely effective pH range (1.0-11.0) under visible light. Furthermore, active oxidating radicals of h(+) and center dot O-2(-) are dominant in photocatalytic degradation for various organic contaminants. This study motivates the atomic design and fabrication of 2D photocatalysts with excellent charge nanospatial separation. (C) 2022 Elsevier Ltd. All rights reserved.

Automated summary

In this study, a nanospatial separation strategy for covalent triazine frameworks (CTFs) was developed to improve their photocatalytic efficiency. By incorporating single-atom cobalt (Co) into CTF-1 nanosheets, the obtained Co/CTF-1 exhibited significantly enhanced efficiency for pollutant photodegradation. The nanospatial separation of charge carriers achieved by the Co single atoms as oxidation centers resulted in improved photo-exciton dissociation and narrow bandgap.