Electronic Structure Theory of Electrolyte/Electrode Interfaces

This chapter explains the essence of electrolyte-electrode systems and introduces one of the modern theoretical methods. This method combines the electronic structure theory described by the density functional theory (DFT) with a continuum electrolyte theory described by a modified Poisson–Boltzmann (MPB) theory. Thus, the interfacial electrolyte is negatively charged to cancel the positive charge induced on the electrode surface. For quantitative evaluations of interfacial electrochemical properties, detailed formulations of the grand partition function are necessary. The pioneering studies provided atomic-scale ionic distributions in the electric double layers formed at interfaces between aqueous electrolytes and metal electrodes. The theory of microscopic interfacial subsystem based on the grand canonical formalism consistently provides the macroscopic responses of free energies to the electrode potential. The DFT–MPB method has been applied to a wide variety of electrochemical reactions at interfaces between aqueous electrolytes and transition metal electrodes.