Impact of Sr‐Incorporation on Cr Oxidation and Water Dissociation in La(1–x)SrxCrO3. Issue 6 (17th January 2018)

• Record Type: Journal Article
• Authors: Stoerzinger, Kelsey A.; Du, Yingge; Ihm, Kyuwook; Zhang, Kelvin H. L.; Cai, Jun; Diulus, J. Trey; Frederick, Ryan T.; Herman, Gregory S.; Crumlin, Ethan J.; Chambers, Scott A.
• Is Part Of: Advanced materials interfaces. Volume 5:Issue 6(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-01-17
• Subjects: ambient pressure X‐ray photoelectron spectroscopy -- chromium oxides -- hydroxylation -- surface oxidation -- surface reduction; Materials science -- Periodicals; 620.11
• DOI: 10.1002/admi.201701363
• Languages: English
• ISSNs: 2196-7350

Abstract

Abstract: The oxidation and reduction of metal oxides and their interaction with the environment play a critical role in material stability and the ability to catalyze reactions. The local change in valence and formation of surface adsorbates affect the oxide electronic structure and chemical reactivity, yet are challenging to probe experimentally. In this paper a detailed study of the oxidation and reduction of Cr in the perovskite oxide family of La(1– x ) Sr x CrO3 using ambient pressure X‐ray photoelectron spectroscopy is presented. The incorporation of Sr increases the propensity to oxidize at the surface, leading to the presence of Cr 4+ and Cr 6+ principally confined to the top unit cell when in equilibrium with O2 gas. These acidic sites are readily reduced to Cr 3+ in equilibrium with H2 O vapor, and the resultant amount of hydroxyls formed from the dissociation of H2 O is directly proportional to the density of surface sites formerly oxidized. The quantification of the redox stability of La(1– x ) Sr x CrO3 and the relationship between the extent of oxidation, reduction, and hydroxylation with Sr yield important insight into the surface functionality during electrochemical applications. Abstract : Sr‐substitution in the perovskite LaCrO3 promotes oxidation of the surface Cr cations in oxidizing conditions. Ambient pressure X‐ray photoelectron spectroscopy quantifies the Cr valence in situ and identifies oxidized Cr as the site for hydroxylation in a water environment, which reduces the Cr oxidation state.