CO2 Electroreduction Performance of Transition Metal Dimers Supported on Graphene: A Theoretical Study

Graphene-based materials are being hotly pursued for energy and environment applications. Inspired by the recent experimental synthesis of Fe-2 dimer supported on graphene (He, Z.; He, K.; Robertson, A. W.; Kirkland, A. I.; Kim, D.; Ihm, J.; Yoon, E.; Lee, G.-D.; Warner, J. H. Nano Lett. 2014, 14, 3766-3772), here using large-scale screening-based density functional theory and microkinetics modeling, we have identified that some transition metal dimers (Cu-2, CuMn, and CuNi), when supported on graphene with adjacent single vacancies (labeled as XY@2SV), perform better in CO2 electroreduction with reduced overpotental and enhanced current density. Specifically, Cu-2@2SV is catalytically active toward CO2 production, similar to Au electrodes but distinct from bulk Cu; MnCu@2SV is selective toward CH4 generation, while NiCu@2SV promotes CH3OH production because of the difference in oxophilicity between incorporated Mn and Ni. The advantages of the outstanding selectivity of products, the high dispersity of spatial distribution, and the reduced overpotentials allow these new systems to be promising catalysts, which will motivate more experimental research in this direction to further explore graphene-based materials for CO2 conversion.