CO₂ electroreduction by transition metal-embedded two-dimensional C₃N: A theoretical study

Transition metal (TM) and nitrogen co-doped carbon (T M-N-C) materials have emerged as the promising single atom catalyst (SAC) for the electrocatalytic CO2 reduction reaction (CO2RR), for which the coordination environment of the anchored single atom plays an important role. Inspired by this, the C3N monolayers embedded with the TM single atoms at the C-C double vacancy, denoted as M-CC (M-Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Mo, Ru, Rh, Pd, Ag, Os, Ir, Pt, and Au), have been evaluated for CO2RR by using the first-principles calculation. We find that the M-CC SACs are of high stability and metallic conductivity, beneficial for the electron transport during the electrocatalytic process. More importantly, all M-CC have high selectivity toward CO2RR versus the hydrogen evolution reaction. Especially, Cu-, Co-, Fe-, and Mn-CC have acceptable or ultra-low limiting potentials of -0.68,-0.48,-0.83, and-0.24 V to produce HCOOH, CH2O, CH3OH, and CH4, respectively. The catalytic activities of M-CC are correlated with the adsorption strength of the key intermediates, further rationalized by the bonding/antibonding population analysis. Our work proposes a new material platform to realize TM-C-N SACs for efficiently electrocatalytic CO2RR, which could provide useful insights into the design of such catalysts.