Unveiling Double Layer Effects in Electrocatalytic CO₂ Reduction

Electrocatalytic CO2 reduction holds great promise for converting CO2 into valuable chemical products. However, the complexity of electric double layer (EDL) hinders a deeper understanding of electrolyte effects on the reaction mechanisms. Here, we developed a multiscale framework that integrates Kohn–Sham DFT calculations for surface reactivity, classical density functional theory (cDFT) for the diffuse layer, and the Booth model to link the local dielectric constant and electric field in the Stern layer. The multiscale model offers a self-consistent description of the relationships among electrode potential, surface charge density, interfacial electric field, the Stern layer dielectric constant, and capacitance across a range of electrolyte types and concentrations. It predicts electrolyte effects on CO production and C2 formation on Ag and Cu electrodes, aligning well with experimental observations. By bridging the surface properties of the electrode and experimental conditions for the electrolyte, the hybrid DFT framework may open new avenues for predicting ionic effects on electrocatalytic reactions, paving the way for the rational design and optimization of electrochemical processes.