From oxide to proton conduction: A quantum‐chemical perspective on the versatility of Sr2Fe1.5Mo0.5O6−δ‐based materials

Abstract

Sr2Fe1.5Mo0.5O6−δ (SFMO) is a promising electrode material for solid oxide electrochemical cells. This perspective highlights the role of first‐principles investigations in unveiling SFMO structural, electronic, and defect properties. In particular, DFT + U provides a reliable and convenient tool for extensive studies on strongly correlated transition‐metal oxides, as SFMO and related systems. The SFMO excellent performances are ascribed to a mixed oxide ion‐electron conductor character. Crucial features are the easy formation of oxygen vacancies and the low oxide migration barrier heights. Aliovalent doping with K+ enables convenient hydration and effective proton transport in bulk SFMO. This opens a route toward new promising triple‐conductor oxides. Besides discussion of specific SFMO applications, our results help to uncover general perovskite‐oxide features and new design principles for oxide‐ and proton‐conducting solid oxide fuel cell electrodes. © 2016 Wiley Periodicals, Inc.