Electrochemical reduction of CO2 on S-triazine-based g-C3N4 surface modified with metal and nonmetal atoms: A DFT study

The electrochemical CO₂ reduction reaction (CO₂RR) is one of the most effective methods for converting greenhouse gases into valuable products. This study explores the surface modification of s-triazine g-C₃N₄ to enhance its performance in CO₂RR through density functional theory calculations. Surface modification techniques, including doping, decorating, and co-decorating with metal and nonmetal atoms (Li, Be, B, C, N, O, F, Al, Si, P, S, and Cl) were used. The designed surfaces were screened according to their energetic and geometric parameters, as well as their ability to activate the adsorbed CO₂ molecule. The adsorption energy of CO₂ on the screened surfaces was found to be between − 0.70 and − 2.53 eV. The selectivity of the catalysts for CO₂RR was demonstrated by comparing the free energy changes for HER and the first step of CO₂ hydrogenation on their surfaces. Among the modified surfaces, 2B2C-C₃N₄ (limiting potential: − 0.33 eV) and 4B-C₃N₄ (limiting potential: − 0.83 eV) exhibited better performance and selectivity in producing CH₃OH and CH₄, respectively. These results demonstrate the significant impact of decorating the surface of g-C₃N₄ with carbon and boron atoms, which makes it an effective catalyst for converting CO₂ into useful fuels.