(686a) Electrolyte Based Tuning of CO2 Electroreduction Selectivity on Copper Surfaces

With growing increase in energy demand and chemical production, electrochemical reduction (ER) of CO₂ can potentially pave the route for generation of sustainable drop-in fuels using renewable wind and solar energy sources. Cu has been identified as a promising electrocatalyst for CO₂ conversion to methane and ethylene, albeit the rates of the electrocatalytic reactions are strongly influenced by the reaction environment and the operating conditions [1,2]. Electrolytic ions are known to impact the rates of electrocatalytic reactions, though a molecular understanding of such impact is not comprehensively understood. Here, we employ a coupled quantum mechanics/molecular mechanics (QM/MM) scheme [3] to investigate the role played by the electrolytic ions under applied potential on the activity-selectivity relationships for CO₂ ER. By varying the concentration and identity of electrolytic salts, we investigate their effect on the reaction energetics and binding strength of reaction intermediates in the CO₂ ER pathway. Using a high throughput combinatorial approach that spans a wide range of electrolytes, we attempt to create design principles for electrolyte based tuning of CO₂ ER selectivity and compare with experimentally measured CO₂ ER selectivities. The results of these studies provide a rationale for improved environment driven design and screening, and allow computation of reaction energetics using nuanced, dynamical models of the electrochemical double layer.

[1] Y. Hori, in Handbook of Fuel Cells: Fundamentals, Technology and Application (VHC Wiley, Chichester, 2003), Vol. 2, 720-733.

[2] A. Murata & Y. Hori, Product selectivity affected by cationic species in electrochemical reduction of CO₂ and CO at a Cu electrode. Bulletin of the Chemical Society of Japan (1991), 64(1), 123-127.

[3] J. Haruyama, T. Ikeshoji and M. Otani, Electrode potential from density functional theory calculations combined with implicit solvation theory. Physical Review Materials (2018), 2(9), p.095801.