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 poten(t)ials 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 C-2 selectivity map in descriptor space (USHE,.GelectrolyteCO), 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.

Automated summary

Solvation models are important for understanding electrochemical reactions. This study developed a framework to evaluate the effects of potential and electrical double layer on CO reduction. Different solvation models were compared and good agreement was found for intermediate products. This framework can be used to predict optimal electrochemical conditions for specific applications.