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.