Toward Operando Modeling of Electrochemical Processes at Metal-Aqueous Solution Interfaces

Understanding electrochemical interfacial processes remains a fundamental challenge due to the multiscale spatiotemporal coupling (mass transport, momentum transport, electrochemical reaction, etc.) between the electrochemical double layer and bulk phases. By combining classical density functional theory and atomic structural information from first-principles calculations, we developed an electrochemical model that bridges atomic-scale interfacial phenomena with macroscopic electrochemical behavior at metal-aqueous solution interfaces under experimental conditions. Our model takes into account the critical interfacial effects, including microscopic double-layer effects, mesoscopic mass transfer, and macroscopic fluid flow. At the microscopic level, key interfacial effects include the quantum effects (metal's electron spillover, adsorption-induced effects of water molecules/ions), solution effects (excluded volume effect and dielectric saturation effect), and redox reactions. In particular, quantum effects are crucial for metal-aqueous solution interfaces. Our model successfully reproduces the experimental differential capacitance curves for the Ag electrode in dilute electrolytes, quantifying the contribution of these effects. Moreover, the study of the hydrogen evolution reaction in dilute electrolytes demonstrates an analytical capability for electrochemical polarization curves across varying experimental conditions. This computationally efficient model enables multiscale interface simulations under experimental conditions, which were previously inaccessible to either atomistic simulations or traditional continuum models. Thus, it provides an improved approach for investigating physicochemical processes in electrochemical systems for energy storage and microelectronics applications.