CO₂ activation at Au(110)-water interfaces: An ab initio molecular dynamics study

The electrochemical reduction of CO₂ into valuable chemicals under mild conditions has become a promising technology for energy storage and conversion in the past few years, receiving much attention from theoretical researchers investigating the reaction mechanisms. However, most of the previous simulations are related to the key intermediates of *COOH and *CO using the computational hydrogen electrode approach under vacuum conditions, and the details of the CO₂ activation are usually ignored due to the model simplicity. Here, we study the CO₂ activation at the Au-water interfaces by considering the dynamics of an explicit water solvent, where both regular ab initio molecular dynamics and constrained ab initio molecular dynamics simulations are carried out to explore the CO₂ adsorption/desorption reactions from the atomic level. By introducing K⁺ cations into Au(110)-water interfacial models, an electrochemical environment under reducing potentials is constructed, where the reaction free energy (0.26 eV) and activation energy (0.61 eV) are obtained for CO₂ adsorption based on the thermodynamic integration. Moreover, the Bader charge analysis demonstrates that CO₂ adsorption is activated by the first-electron transfer, forming the adsorbed CO₂ ^- anion initiating the overall catalytic reaction.