Abstract: Methods for tailoring an oxygen defect concentration, such as oxygen vacancies, in a transition metal oxide and the resulting materials are provided. An epitaxial strain, such as in the form of a biaxial tensile strain of up to 5%, is applied to the transition metal oxide to increase the oxygen defect concentration in the transition metal oxide to result in a product comprising the transition metal oxide having an increased oxygen defect concentration.

Abstract: Rapid, reversible redox activity may be accomplished at significantly reduced temperatures, as low as about 200° C., from epitaxially stabilized, oxygen vacancy ordered SrCoO2.5 and thermodynamically unfavorable perovskite SrCoO3-?. The fast, low temperature redox activity in SrCoO3-? may be attributed to a small Gibbs free energy difference between the two topotactic phases. Epitaxially stabilized thin films of strontium cobaltite provide a catalyst adapted to rapidly transition between oxidation states at substantially low temperatures. Methods of transitioning a strontium cobaltite catalyst from a first oxidation state to a second oxidation state are described.

Abstract: Rapid, reversible redox activity may be accomplished at significantly reduced temperatures, as low as about 200° C., from epitaxially stabilized, oxygen vacancy ordered SrCoO2.5 and thermodynamically unfavorable perovskite SrCoO3-?. The fast, low temperature redox activity in SrCoO3-? may be attributed to a small Gibbs free energy difference between the two topotactic phases. Epitaxially stabilized thin films of strontium cobaltite provide a catalyst adapted to rapidly transition between oxidation states at substantially low temperatures. Methods of transitioning a strontium cobaltite catalyst from a first oxidation state to a second oxidation state are described.