Ab Initio Thermodynamic Modeling of Electrified Metal–Oxide Interfaces: Consistent Treatment of Electronic and Ionic Chemical Potentials

Solid
oxide fuel cells are attractive devices in a sustainable
energy context because of their fuel flexibility and potentially highly
efficient conversion of chemical to electrical energy. The performance
of the device is to a large extent determined by the atomic structure
of the electrode–electrolyte interface. Lack of atomic-level
information about the interface has limited the fundamental understanding,
which further limits the opportunity for optimization. The atomic
structure of the interface is affected by electrode potential, chemical
potential of oxygen ions, temperature, and gas pressures. In this
paper we present a scheme to determine the metal–oxide interface
structure at a given set of these environmental parameters based on
quantum chemical calculations. As an illustration we determine the
structure of a Ni-YSZ anode as a function of electrode potential at
0 and 1000 K. We further describe how the structural information can
be used as a starting point for accurate calculations of the kinetics
of fuel oxidation reactions, in particular the hydrogen oxidation
reaction. More generally, we anticipate that the scheme will be a
valuable theoretical tool to describe solid–solid electrochemical
interfaces.