Generalized Surface Coordination Number as an Activity Descriptor for CO2 Reduction on Cu Surfaces

Surface engineering has proved effective in enhancing activities of CO2 reduction reaction (CO2RR) on Cu. However, predictive guidance is necessary for the surface engineering to reach its full potential. We propose that the generalized coordination number (GCN) can be used as a descriptor to characterize CO2RR on Cu surfaces. A set of linear scaling relations between the binding energy of CO2RR intermediates and GCN are established to construct a volcano-type coordinationactivity plot and from which we can derive the theoretical overpotential limit on Cu surfaces. We predict that the dimerized (111) surface yields the lowest possible overpotential on Cu for CO2RR to methane, and surface engineering by creating adatoms could lower CO2RR overpotentials and simultaneously suppress the competing hydrogen evolution reaction.