Reliable first-principles calculations of electrochemical processes require accurate prediction of the interfacial capacitance, a challenge for current computationally-efficient continuum solvation methodologies. We develop a model for the double layer of a metallic electrode that reproduces the features of the experimental capacitance of Ag(100) in a non-adsorbing, aqueous electrolyte, including a broad hump in the capacitance near the Potential of Zero Charge (PZC), and a dip in the capacitance under conditions of low ionic strength. Using this model, we identify the necessary characteristics of a solvation model suitable for first-principles electrochemistry of metal surfaces in non-adsorbing, aqueous electrolytes: dielectric and ionic nonlinearity, and a dielectric-only region at the interface. The dielectric nonlinearity, caused by the saturation of dipole rotational response in water, creates the capacitance hump, while ionic nonlinearity, caused by the compactness of the diffuse layer, generates the capacitance dip seen at low ionic strength. We show that none of the previously developed solvation models simultaneously meet all these criteria. We design the Nonlinear Electrochemical Soft-Sphere solvation model (NESS) which both captures the capacitance features observed experimentally, and serves as a general-purpose continuum solvation model.
Confinement-controlled Water Engenders High Energy Density Electrochemical-double-layer Capacitance
Skolkovo Institute of Science and Technology（斯克隆沃科学技术研究所）；Karlsruhe Institute of Technology（卡尔斯鲁厄理工学院）；École Polytechnique Fédérale de Lausanne (EPFL)（洛桑联邦理工学院）；Max Planck Institute for Polymer Research（马克斯·普朗克高分子研究所）
A Theoretical Investigation of the Grand- and the Canonical Potential Energy Surface: The Interplay between Electronic and Geometric Response at Electrified Interfaces
