Rare-earth metal neodymium anchored into graphene as a promising CO2 reduction electrocatalyst by regulating the coordination environment

Carbon-based single atom catalysts (SACs) are promising electrocatalysts in the field of carbon dioxide reduction reactions (CO₂RR) due to their high efficiency and environmental friendliness, in which the coordination environment is the key factor determining their intrinsic catalytic activity. Furthermore, rare-earth-based SACs have shown great potential on CO₂RR in recent years. Meanwhile, various studies have focused on combining metals with N-doped graphene, which together form potential M_x-N_y-C active sites. This work systematically investigates the impact of varying N/C coordination numbers on Nd atoms in graphene (Nd-N_xC_6-x, x = 0–5) on the CO₂RR reaction mechanism and catalytic performance through density functional theory methods. Detailed Gibbs free energy calculation results indicate that most catalysts undergo a two-electron reduction pathway. For Nd-N₃C₃, Nd-N₃C₃–1, Nd-N₃C₃–2, Nd-N₄C₂, Nd-N₄C₂–1, Nd-N₄C₂–2, and Nd-N₅C, HCOOH is the main product, with low U_L values of -0.18, -0.17, -0.03, -0.10, -0.11, -0.09, and -0.10 V, respectively. In summary, our research results not only indicate that N atoms with different coordination numbers can improve the product selectivity and catalytic activity of catalysts, but also may provide valuable theoretical insights for studying the application of rare-earth-based SACs.