Research on cobalt-doping sites in g-C₃N₄ framework and photocatalytic reduction CO₂ mechanism insights

The novel Co-doping combined with mesoporous g-C₃N₄-based photocatalyst was constructed, and the Co-CN showed impressive photocatalytic reduction CO₂ activity. Employing the DFT computation, we discussed the possible Co doping sites on g-C₃N₄ framework, as well as the effects of band gaps, optical properties, and various densities of state (DOS) on photocatalytic activity. The adsorption energy calculation proved that the substitution and interstitial doping Co atoms in g-C₃N₄ crystal unit cell was the stable configuration. The coexistence substitution and substitution the monolayer g-C₃N₄ showed serious deformation. It indicated that the introduction of Co atoms leads g-C₃N₄ molecular orbital redistribution and Co tends to occupy the conduction band, due to its weak electronegativity. Moreover, the DFT and experiment results pointed out that the doped-Co narrowed g-C₃N₄ bandgap and increased light absorption from 450 to 800 nm, the improved charge carrier separation efficiency was originated from Co atom the unfilled 4 f and the empty 5d orbital act as electron capturing center. This research indicates the availability of transition metal g-C₃N₄ with conducive photocatalytic activity.