First-Principles Analyses of Nanoionic Effects atOxide–Oxide Heterointerfaces for Electrochemical Applications

Defect segregation at homo- and heterointerfaces enables heterogeneous doping of functional nanocomposites for enhanced charge and mass transport or storage properties compared to homogeneously doped bulk materials. The direction and extent of interfacial defect segregation is governed by the chemical potentials of charged species in the two phases. In this contribution we show that the extent of homogeneous doping at a model heterointerface can be tuned by both materials selection and homogeneous doping of the bulk phases from first-principles calculations. Homogenous doping is found to dictate the direction of defect segregation at a heterointerface, enabling electrostatic potential differences across a model SrTiO3 and BaZrO3 interface in excess of 3 V. The results suggest that composites of donor-doped SrTiO3 and acceptor-doped BaZrO3 exhibit significant mass storage capacity, enabling use for hydrogen storage or thermochemical water splitting.