Mechanism of transition-metal-cluster-anchored g-C3N4 for the electrochemical catalytic hydrogenation of carbon dioxide to C1 products

Applying density functional theory, this research investigates the CO2RR catalytic performances of six sub-nano transition metal clusters (M4@g-C3N4, M = Cr, Mn, Fe, Co, and Cu) supported on graphite carbon nitride. The structural analysis first revealed considerable binding energies of M4@g-C3N4 (-8.33 eV to-6.02 eV), ensuring their structural stability for the CO2RR. Second, the Cu4@g-C3N4 cluster most effectively promoted the formation of HCOOH products, with a limiting potential (UL) of-0.88 V. The U L s of CO production by Co4@g-C3N4 and Cu4@ g-C3N4 during the reaction were-0.35 V and-0.33 V, respectively, indicating that these clusters most effectively catalyzed CO production. Finally, the Co4@g-C3N4 and Cu4@g-C3N4 clusters best catalyzed the formation of CH3OH and CH4 products. The U L s of CO2 reduction to CH3OH and CH4 were-0.68 and-0.68 V, respectively, when catalyzed by Co4@g-C3N4 and-0.53 and-0.78 V, respectively, when catalyzed by Cu4@g- C3N4.