Activation of CO₂ on Copper Surfaces: The Synergy between Electric Field, Surface Morphology, and Excess Electrons

In this work, we use density functional theory calculations to study the combined effect of external electric fields, surface morphology, and surface charge on CO₂ activation over Cu(111), Cu(211), Cu(110), and Cu(001) surfaces. We observe that the binding energy of the CO₂ molecule on Cu surfaces increases significantly upon increasing the applied electric field strength. In addition, rougher surfaces respond more effectively to the presence of the external electric field toward facilitating the formation of a carbonate-like CO₂ structure and the transformation of the most stable adsorption mode from physisorption to chemisorption. The presence of surface charges further strengthens the electric field effect and consequently causes an improved bending of the CO₂ molecule and C–O bond length elongation. On the other hand, a net charge in the absence of an externally applied electric field shows only a marginal effect on CO₂ binding. The chemisorbed CO₂ is more stable and further activated when the effects of an external electric field, rough surface, and surface charge are combined. These results can help to elucidate the underlying factors that control CO₂ activation in heterogeneous and plasma catalysis, as well as in electrochemical processes.