期刊
JOURNAL OF MATERIALS CHEMISTRY A
卷 6, 期 47, 页码 24378-24388出版社
ROYAL SOC CHEMISTRY
DOI: 10.1039/c8ta08355j
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资金
- National Science Foundation (NSF) [NSF-DMR-1464112]
- Advanced Light Source, a DOE Office of Science User Facility [DE-AC02-05CH11231]
- U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences, Materials Science and Engineering Division
The bulk-to-surface Sr segregation can seriously compromise the stability of oxygen electrocatalysis in La1-xSrxCoO3- and limit its practical applications such as in solid oxide fuel cells. Here we show via in situ ambient pressure X-ray photoelectron spectroscopy (APXPS) that the surface Sr-segregation is a kinetically fast process and the equilibrium surface Sr-concentration follows Arrhenius law from 250 to 520 degrees C at a fixed p(O2) = 1 x 10(-3) atm. We also show that application of a nanoscaled, atomic layer deposition (ALD) derived ZrO2 overcoat can effectively suppress the Sr-segregation by reducing the surface concentration of oxygen vacancies. Electrochemical impedance spectroscopy (EIS) study further confirms that the ALD-ZrO2-coated LSCo epitaxial film exhibits a much lower and more stable polarization resistance than the uncoated one at 550 degrees C for >300 hours, suggesting that Sr-segregation is the source of the higher resistance.
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