title: Operando and in situ X-ray spectroscopies of degradation in La0.6Sr0.4Co0.2Fe0.8O(3-δ) thin film cathodes in fuel cells.
abstract: Information from ex situ characterization can fall short in describing complex materials systems simultaneously exposed to multiple external stimuli. Operando X-ray absorption spectroscopy (XAS) was used to probe the local atomistic and electronic structure of specific elements in a La0.6Sr0.4Co0.2Fe0.8O(3-δ) (LSCF) thin film cathode exposed to air contaminated with H2O and CO2 under operating conditions. While impedance spectroscopy showed that the polarization resistance of the LSCF cathode increased upon exposure to both contaminants at 750 °C, XAS near-edge and extended fine structure showed that the degree of oxidation for Fe and Co decreases with increasing temperature. Synchrotron-based X-ray photoelectron spectroscopy tracked the formation and removal of a carbonate species, a Co phase, and different oxygen moieties as functions of temperature and gas. The combined information provides insight into the fundamental mechanism by which H2O and CO2 cause degradation in the cathode of solid oxide fuel cells.
authors.affiliation: Center for Innovative Fuel Cell and Battery Technologies, School of Materials Science and Engineering, Georgia Institute of Technology, 771 Ferst Drive NW, Atlanta, GA 30332-0245 (USA).
authors.forename: Samson Y
authors.initials: SY
authors.lastname: Lai
authors.forename: Dong
authors.initials: D
authors.lastname: Ding
authors.forename: Mingfei
authors.initials: M
authors.lastname: Liu
authors.forename: Meilin
authors.initials: M
authors.lastname: Liu
authors.forename: Faisal M
authors.initials: FM
authors.lastname: Alamgir
mesh_terms: D002245:Carbon Dioxide / Q000737:chemistry; D003035:Cobalt / Q000737:chemistry*; D058266:Dielectric Spectroscopy; D011211:Electric Power Supplies; D004566:Electrodes; D007501:Iron / Q000737:chemistry*; D007811:Lanthanum / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry; D056951:Photoelectron Spectroscopy; D013324:Strontium / Q000737:chemistry*; D014867:Water / Q000737:chemistry; D056928:X-Ray Absorption Spectroscopy
chemical_list: D010087:Oxides; D014867:Water; D002245:Carbon Dioxide; D003035:Cobalt; D007811:Lanthanum; D007501:Iron; D013324:Strontium
keywords: EXAFS spectroscopy; X-ray absorption spectroscopy; ceramics; fuel cells; photoelectron spectroscopy