Intrinsic Dipole Moments and Electron Transfer at the MIEC-Gas Interfaces

The magnitude of the electrostatic potential at the surface of a mixed ionic-electronic conducting (MIEC) solid-oxide cell (SOC) electrode is dependent on the intrinsic dipole moment of adsorbed gas species. Using density functional theory, we have investigated the electrostatic nature of hydroxyl adsorbates and the kinetics of electron transfer in the water electrolysis reaction at the pristine ceria-gas interface. First principles data ware used in a generalised kinetic model to predict reaction kinetics near equilibrium and under an applied overpotential. The mechanistic understanding gained from this model is widely applicable to a range of MIEC systems and provides a basis upon which the operating conditions can be tailored.