(651e) Benchmarking Solvation Effects for Electroreduction of CO over Cu-Based Catalysts

The electrocatalytic reduction of CO₂ to CO and other chemical compounds contributes to a clean and sustainable energy future. The current theoretical understanding of the reaction on Cu is heavily reliant on a simplified electrochemical model, which makes numerous assumptions about the nature of the charged electrode-electrolyte interface. Although varying degrees of solvating environments often stabilize reaction intermediates, there is little consensus on how to adequately describe solvation in modeling these chemical processes. For accurate and reliable physical models of multistep CO reduction reaction, descriptions of interfacial dielectric field and solvating environment are critical. This work reformulates Nørskov's Computational Hydrogen Electrode (CHE) model, which treats electrochemical reactions as coupled proton-electron transfer events, where the effect of electric field on adsorption energies was neglected. We benchmark explicit, implicit, and hybrid explicit/implicit solvation techniques applied to a multistep CO reduction mechanism. In addition to explicit solvent model of the metal-electrolyte interface, we also tested VASPsol's implicit solvation treatment, which treats the electrolyte as a dielectric continuum. Lastly, the hybrid solvation scheme is implemented in a recently developed DFT–continuum technique based on the effective screening medium method and the reference interaction site model (ESM-RISM). A potential-dependent electric field effect was validated across all three solvation treatments (Figure 1). The implications including reasons for visible differences and limitations of these solvation models will be discussed, without limiting to the current system but also for other reaction mechanisms. We also present the microkinetic reaction rates from these three models and compare them to experimental measurements. This work highlights the critical need for integrating energy contributions from electric field and solvation effects into the existing electrochemistry models. This work is funded through CRADA agreement between LLNL, Stanford University, TOTAL.