Ab Initio Dynamics Insights: The Activity and Selectivity of Supercritical CO2 Reduction Reaction on Cu Surfaces

The electrocatalytic reduction of carbon dioxide (CO 2 ) using renewable energies is widely recognized as a promising approach to establishing a sustainable closed carbon cycle economy. To date, the focus of this field has primarily been on the electrolysis of ambient pressure CO 2 , where the critical factors include the limited solubility of CO 2 in many electrolytes and its hindered mass transport to the electrodes. However, industrial CO 2 is typically pressurized during capture, transport, and storage, often existing in dissolved form. Herein, we shift our focus to the potential applications of supercritical CO 2 (SCO 2 ) obtained from industrial storage. By using ab initio molecular dynamics simulations integrated with the slow-growth sampling (SG-AIMD) method, we conducted a systematic investigation into the supercritical CO 2 reduction reaction (SCO 2 RR) on various Cu surfaces. Our findings reveal that Cu(111) favors CO* generation, while Cu(100) promotes formic acid production under the reaction conditions of SCO 2 R. In the meantime, we present a comprehensive free energy diagram incorporating both kinetics and thermodynamics of SCO 2 and Cu atom migration, which illustrates the critical role of Cu sites with high coordination numbers induced by intermediate adsorption in the overall performance of CO 2 electroreduction into formic acid. This study would lay the foundation for potential applications of supercritical CO2 and the designing of effective catalysts in the future.