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Chemical Surface Exchange of Oxygen on CeO2-δ in O2/H2O atmosphere

Abstract

The chemical surface reaction rate constant of undoped ceria, kChem, was measured at 1400 °C in the range of (~0 ≤ (pH2O / atm) ≤ 0.163(9)) and (10-3.85 ≤ (pO2 / atm) ≤ 10-2.86) via electrical conductivity relaxation methodology. In humidified atmosphere, kChem is derived as a summation of kChem,O2 and kChem,H2O, which are respectively relevant to O2 and H2O as oxidizing agents for the oxidation of ceria. The kChem,O2 and kChem,H2O are successfully separated, thereby the total surface reaction rate constant is found to follow the correlation kChem/cm·s-1 = 10-(1.35±0.07)×(pO2 / atm)0.72±0.07 + 10-(3.85±0.03)×(pH2O / atm)0.36±0.03. The implication of the results is that H2O potentially plays a role of oxidants as increasing temperature and/or decreasing oxygen partial pressure, thus in such thermodynamic conditions, pH2O besides temperature and pO2 needs to be carefully treated in surface reaction study.

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Publication details

The article was received on 01 Sep 2017, accepted on 09 Oct 2017 and first published on 09 Oct 2017


Article type: Paper
DOI: 10.1039/C7CP05969H
Citation: Phys. Chem. Chem. Phys., 2017, Accepted Manuscript
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    Chemical Surface Exchange of Oxygen on CeO2-δ in O2/H2O atmosphere

    H. JI, X. Xu and S. M. Haile, Phys. Chem. Chem. Phys., 2017, Accepted Manuscript , DOI: 10.1039/C7CP05969H

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