In Situ Characterization of Ceria Oxidation States in High-Temperature Electrochemical Cells with Ambient Pressure XPS

被引：80

作者：

DeCaluwe, Steven C. ^{[1
]}

Grass, Michael E. ^{[2
]}

Zhang, Chunjuan ^{[1
]}

El Gabaly, Farid ^{[3
]}

Bluhm, Hendrik ^{[2
]}

Liu, Zhi ^{[2
]}

Jackson, Gregory S. ^{[1
]}

McDaniel, Anthony H. ^{[3
]}

McCarty, Kevin F. ^{[3
]}

Farrow, Roger L. ^{[3
]}

Linne, Mark A. ^{[3
]}

Hussain, Zahid ^{[3
]}

Eichhorn, Bryan W. ^{[1
]}

机构：

[1] Univ Maryland, College Pk, MD 20742 USA

[2] Univ Calif Berkeley, Lawrence Berkeley Lab, Berkeley, CA 94720 USA

[3] Sandia Natl Labs, Livermore, CA 94551 USA

来源：

JOURNAL OF PHYSICAL CHEMISTRY C | 2010年 / 114卷 / 46期

基金：

美国能源部;

关键词：

RAY PHOTOELECTRON-SPECTROSCOPY; OXIDE FUEL-CELLS; SOFC ANODES; REDUCTION; SURFACES; CEO2; NANOPARTICLES; HYDROGEN; NI; ELECTROLYSIS;

D O I：

10.1021/jp107694z

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

Ambient pressure X-ray photoelectron spectroscopy (XPS) is used to measure near-surface oxidation states and local electric potentials of thin-film ceria electrodes operating in solid oxide electrochemical cells for H2O electrolysis and H-2 oxidation. Ceria electrodes which are 300 nm thick are deposited on YSZ electrolyte supports with porous Pt counter electrodes for single-chamber tests in H-2/H2O mixtures. Between 635 and 740 degrees C, equilibrium (zero-bias) near-surface oxidation states between 70 and 85% Ce3+ confirm increased surface reducibility relative to bulk ceria. Positive cell biases drive H2O electrolysis on ceria and further increase the percentage of Ce3+ on the surface over 100 mu m from an Au current collector, signifying broad regions of electrochemical activity due to mixed ionic-electronic conductivity of ceria. Negative biases to drive H-2 oxidation decrease the percentage of Ce3+ from equilibrium values but with higher electrode impedances relative to H2O electrolysis. Additional tests indicate that increasing H-2-to-H2O ratios enhances ceria activity for electrolysis.

引用

页码：19853 / 19861

页数：9

共 51 条

[1] Mechanisms and rate laws for oxygen exchange on mixed-conducting oxide surfaces [J].