MODELING OF ELECTRIC DOUBLE LAYER ON A METAL-ELECTROLYTE INTERFACE IN THE FRAMEWORK OF SELF-CONSISTENT FIELD THEORY

Mazur D.A.⁽¹⁾, Brandyshev P.E.⁽¹⁾, Doronin S.V.⁽²⁾, Budkov Y.A.^(1,3)

⁽¹⁾ HSE University

123458, Moscow, Tallinskaya st., 34

⁽²⁾ N.N. Semenov Federal Research Center for Chemical Physics RAS

119991, Moscow, Kosygina st., 4

⁽³⁾ G.A. Krestov Institute of Solution Chemistry of RAS

153045, Ivanovo, Akademicheskaya st., 1

Modeling the electrical double layer at a metal electrode–electrolyte interface remains a fundamental challenge due to the coupled electrostatic, steric, and chemical interactions operating across different length scales. We present a self-consistent field theory incorporating key physical components neglected in classical models: short-range specific interactions, ion hydration, dielectric saturation of the solvent, and excluded volume effects. By solving a modified Poisson–Boltzmann equation derived from the grand thermodynamic potential, with parameters informed by quantum chemistry calculations, we accurately reproduce the differential capacitance of aqueous electrolytes at silver electrodes. The approach was first validated on the Ag(100) face for systems without specific adsorption (KPF₆, NaClO₄) [1], then extended to account for specific adsorption and partial charge transfer in the Ag(100)/NaF system [2]. A Morse potential for adsorption energy and explicit charge transfer yielded fitted parameters in good agreement with quantum chemical and ab initio molecular dynamics estimates. We further apply the model to Ag(111) and Ag(110) faces in NaF electrolyte, obtaining face-dependent adsorption energies, potential range parameters, and partial charge transfer coefficients that reveal how ion–surface and water–surface interactions vary with surface structure. These results explain the experimentally observed ordering of fluoride adsorption strength across the three low-index silver faces and establish a pathway for incorporating electrode crystallography into continuum EDL modelling, with direct applications in supercapacitors and electrochemical energy storage.

1. Mazur DA, Brandyshev PE, Doronin SV, Budkov YA. Understanding the Electric Double Layer at the Electrode-Electrolyte Interface: Part I - No Ion Specific Adsorption. Chemphyschem.

2. Daria A. Mazur, Petr E. Brandyshev, Doronin S., Yury A. Budkov. Understanding the electric double layer at the electrode–electrolyte interface: Part II - specific adsorption and partial charge transfer // Electrochimica Acta. 2026. Vol. 545. Article 147660