Installing active metal species in a covalent triazine framework for highly efficient and selective photocatalytic CO2 reduction

Abstract

The decoration of metal active sites to regulate the catalytic activity of polymeric photocatalysts is highly significant. In this study, a photosensitive phenanthroline-containing covalent triazine framework (PT-CTF) was synthesized and various metal ions (Co²⁺, Ni²⁺, and Zn²⁺) were incorporated into the PT-CTF through interactions with the phenanthroline unit to enhance the photocatalytic CO₂ reduction performance. The characterization results showed that all metallized PT-CTF (M-PT-CTF) materials exhibited significantly improved photochemical properties and CO₂ adsorption capabilities. In particular, the Ni-coordinated PT-CTF (Ni-PT-CTF) demonstrated an impressive CO generation rate of 784.5 μmol g⁻¹ h⁻¹ and a selectivity of 96.6% without any photosensitizers, which was approximately 10.2 times higher than that of the pristine PT-CTF under visible light irradiation. Experimental studies and theoretical calculations indicated that the enhanced photocatalytic performance was due to the incorporated Ni sites in the PT-CTF structure, which facilitated charge carrier dynamics, reduced energy barriers for *COOH formation, and enhanced CO₂ activation and CO desorption. This work provides insight for the designing and fabrication of advanced polymeric photocatalysts at the molecular level for efficient CO₂ conversion.