Quantifying the Driving Force for the Surface Reconstruction of Copper under Electrochemical Reduction of CO₂ by First-Principles Simulations

Cu is one of the most widely used catalysts in the electrochemical CO₂ reduction reaction (CO₂RR) due to its unique ability to convert CO₂ to C₂₊ products. However, surface reconstruction of Cu significantly affects the activity and stability of Cu catalyst. In this work, density functional theory (DFT) coupled with implicit solvation ab initio molecular dynamics (AIMD) was employed to unveil the possible migration pathways of surface Cu atoms during the structural evolution processes under CO₂RR. Surface energy, as the intrinsic thermodynamic driving force of surface reconstruction, is distributed to individual surface Cu atoms and shows a quasi-linear relationship with their generalized coordination number (GCN), demonstrating a maximum driving force of ∼1.10 eV under the applied electric field. The *CO adsorbate weakens the binding of surface Cu atoms, resulting in a maximum vertical displacement of Cu atoms of up to 0.8 Å. In contrast, *H on Cu(100) at high coverage induces a horizontal extruding effect on the surface Cu atoms, causing them to move up to 2 Å. The observable migration of surface Cu atoms in the AIMD run occurs only on Cu adatoms, with the adsorption of pure *H or coadsorption of *CO and *H.