title: Reversible redox reactions in an epitaxially stabilized SrCoO(x) oxygen sponge.
abstract: Fast, reversible redox reactions in solids at low temperatures without thermomechanical degradation are a promising strategy for enhancing the overall performance and lifetime of many energy materials and devices. However, the robust nature of the cation's oxidation state and the high thermodynamic barrier have hindered the realization of fast catalysis and bulk diffusion at low temperatures. Here, we report a significant lowering of the redox temperature by epitaxial stabilization of strontium cobaltites (SrCoO(x)) grown directly as one of two distinct crystalline phases, either the perovskite SrCoO(3-δ) or the brownmillerite SrCoO(2.5). Importantly, these two phases can be reversibly switched at a remarkably reduced temperature (200-300 °C) in a considerably short time (< 1 min) without destroying the parent framework. The fast, low-temperature redox activity in SrCoO(3-δ) is attributed to a small Gibbs free-energy difference between two topotatic phases. Our findings thus provide useful information for developing highly sensitive electrochemical sensors and low-temperature cathode materials.
authors: Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors: Hyoungjeen
authors: H
authors: Jeen
authors: Woo Seok
authors: WS
authors: Choi
authors: Michael D
authors: MD
authors: Biegalski
authors: Chad M
authors: CM
authors: Folkman
authors: I-Cheng
authors: IC
authors: Tung
authors: Dillon D
authors: DD
authors: Fong
authors: John W
authors: JW
authors: Freeland
authors: Dongwon
authors: D
authors: Shin
authors: Hiromichi
authors: H
authors: Ohta
authors: Matthew F
authors: MF
authors: Chisholm
authors: Ho Nyung
authors: HN
authors: Lee
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