Mechanism of CO2 photoreduction by selenium-doped carbon nitride with cobalt clusters as cocatalysts

Doping is an efficient strategy for improving the photocatalytic activity and tuning the electronic structure of carbon nitride. Selenium-doped melon carbon nitride (Se-doped melon CN) as a promising photocatalyst for CO2 reduction is investigated using density functional theory calculations. In addition, considering the special role of a cocatalyst in CO2 reduction, we have explored the electronic and optical properties of Co-4 clusters loaded on the Se-doped melon CN surface. After loading cobalt clusters, CO2 activation is significantly improved, with preference for the 8-electron product CH4, as the 2-electron products have higher desorption energies. Overall, this work provides a microscopic understanding of the CO2 reduction mechanism on Se-doped melon CN with cobalt as the co-catalyst.