Computational screening of effective g-C₃N₄ based single atom electrocatalysts for the selective conversion of CO₂

Two-dimensional (2D) material-based single-atom catalysts (SACs) have demonstrated their potential in electrochemical reduction reactions but exploring suitable 2D material-based SACs for the CO₂ reduction reaction (CO₂RR) by experiments is still a formidable task. In this study, theoretical screening of transition metal (TM)-doped graphitic carbon nitride (g-C₃N₄) materials as catalysts for the CO₂RR was systematically performed based on density functional theory (DFT) calculations. An indicator for the selective formation of one carbon (C1) products was developed to screen catalysts that are active and selective in the CO₂RR. The results indicated that Ti- and Ag-g-C₃N₄ demonstrate excellent catalytic activity and selectivity for the formation of CO and HCOOH, with limiting potentials of -0.330 and -0.096 V, respectively, while Cr-g-C₃N₄ exhibits the highest catalytic activity for yielding CH₃OH and CH₄ (-0.355 and -0.420 V, respectively), but none of the screened catalysts have been identified as ideal candidates for the selective production of CH₃OH and CH₄. Furthermore, Bader charge analysis suggested that excessive electron transfer from TM leads to stronger adsorption of intermediates and high limiting potentials, which subsequently result in lower catalytic activity. This work provides theoretical insights into the effective screening of active and selective 2D material-based SACs which has the potential to significantly reduce the time and resources required for the discovery of novel electrocatalysts for the controlled formation of various products.