Single-site cobalt catalyst embedded in a covalent triazine-based framework (CTF) for photocatalytic CO2 reduction

Abstract

Transforming CO₂ into carbonaceous fuels using photocatalysts is an attractive approach to address both the energy crisis and environmental issues simultaneously. However, the task of fabricating catalysts with exceptional photoreduction activity presents significant challenges in the field. Recently, cobalt-coordinated covalent organic frameworks (COFs) have drawn significant attention in the domain of CO₂ photoreduction to CO owing to their notable electron affinity and carefully designed structure. In context to this, herein, a series of metal-loaded covalent triazine-based framework (CTF) photocatalysts have been prepared, where single Co²⁺ sites have been incorporated through a simple deposition method. The obtained Co-embedded CTF exhibited enhanced photocatalytic CO₂ conversion to CO, which generates 1515 μmol CO, which is 37-fold more than that exhibited by pristine CTF-TPE (40 μmol) during the 2 h photocatalytic run. Furthermore, studies of EXAFS and XPS have been performed to examine the presence of single Co²⁺ sites and their role in the high-efficiency rate of CO₂ conversion to CO. In addition, a plausible mechanism has been proposed for photocatalytic CO₂ reduction through our experimental studies. This study paves the path for developing new catalysts of superior performance in the realm of CTF-based CO₂ photoreduction.