A Comparative Study of Electrical Double Layer Effects for CO Reduction Reaction Kinetics

Solvation models describe how the interactions between the solutes and solvents affect the reactivity and selectivity in electrochemical processes. In this study, we developed a framework for evaluating the effects of applied potential and electrical double layer on CO reduction (COR), comparing fully explicit, implicit, and hybrid solvation models at the standard hydrogen electrode (SHE) scale. We analyzed all crucial intermediates leading to the production of C₁ and C₂ products and found good agreement across these models. Some notable differences were observed in the implicit description of *C and *CO adsorption at higher overpotentials and overall trends in the adsorption energies within the hybrid model. Using this unified SHE framework, we built comparable microkinetic models for COR kinetics and rates. Despite small differences in thermodynamics, solvation-model-based microkinetic simulations showed good agreement for onset potentials against the benchmark experiment. Only qualitative difference was observed for C₁₊ versus hydrogen evolution at high overpotentials for the implicit model. Finally, we constructed a generalized C₂ selectivity map in descriptor space (U_SHE, ΔG_electrolyte^CO), which highlights the limitations of a copper-based COR catalyst and guides the search for optimal descriptor parameters to maximize C₂ selectivity. These findings demonstrate the importance of considering electrical double layer effects in reduction reactions and offer a useful framework for comparing solvation models and predicting optimal electrochemical conditions for specific applications. Computational data available at https://www.catalysis-hub.org/publications/PasumarthiDoubleLayer2023