Acidity of surface-infiltrated binary oxides as a sensitive descriptor of oxygen exchange kinetics in mixed conducting oxides

Clement Nicollet; Cigdem Toparli; George F. Harrington; Thomas Defferriere; Bilge Yildiz; Harry L. Tuller

doi:10.1038/s41929-020-00520-x

Acidity of surface-infiltrated binary oxides as a sensitive descriptor of oxygen exchange kinetics in mixed conducting oxides

Clement Nicollet, Cigdem Toparli, George F. Harrington, Thomas Defferriere, Bilge Yildiz, Harry L. Tuller

Department of Chemistry

Research output: Contribution to journal › Article › peer-review

63 Citations (SciVal)

Abstract

Improving the kinetics of O₂ reduction on oxide surfaces is critical in many energy and fuel conversion technologies. Here we show that the acidity scale for binary oxides is a powerful descriptor for tuning and predicting oxygen surface exchange kinetics on mixed conducting oxides. By infiltrating a selection of binary oxides from strongly basic (Li₂O) to strongly acidic (SiO₂) onto the surface of Pr_0.1Ce_0.9O_2-δ samples, it was possible to vary the chemical surface exchange coefficient k_chem by 6 orders of magnitude, with basic oxides such as Li₂O increasing k_chem by nearly 1,000 times, with surface concentrations as low as 50 ppm impacting k_chem. Strikingly, although the pre-exponential of k_chem scales linearly with the acidity of the infiltrated binary oxide, there is nearly no change in the activation energy. The origin of these dramatic changes is proposed to arise from the systematic increase in electron concentration at the Pr_0.1Ce_0.9O_2-δ surface with the decreasing acidity of the infiltrated binary oxide. [Figure not available: see fulltext.]

Original language	English
Pages (from-to)	913-920
Number of pages	8
Journal	Nature Catalysis
Volume	3
Issue number	11
DOIs	https://doi.org/10.1038/s41929-020-00520-x
Publication status	Published - 5 Oct 2020

Bibliographical note

Funding Information:
This research was primarily supported by the US Department of Energy (DOE), National Energy Technology Laboratory (NETL), Office of Fossil Energy under Award no. DE-FE0031668—Self-Regulating Surface Chemistry for More Robust Highly Durable Solid Oxide Fuel Cell Cathodes. Supplementary support was provided by the US DOE, Office of Science, Basic Energy Sciences (BES), under Award no. DE-SC0002633—Chemomechanics of Far-From-Equilibrium Interfaces (XPS studies). G.F.H. acknowledges support from a Kakenhi Grant-in-Aid for Encouragement of Young Scientists (B) Award (no. JP18K13992) (TEM studies). Thanks go to A. Grimaud and D. Kalaev for helpful discussions.

Publisher Copyright:
© 2020, The Author(s), under exclusive licence to Springer Nature Limited.

ASJC Scopus subject areas

Catalysis
Bioengineering
Biochemistry
Process Chemistry and Technology

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10.1038/s41929-020-00520-x

Cite this

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title = "Acidity of surface-infiltrated binary oxides as a sensitive descriptor of oxygen exchange kinetics in mixed conducting oxides",

abstract = "Improving the kinetics of O2 reduction on oxide surfaces is critical in many energy and fuel conversion technologies. Here we show that the acidity scale for binary oxides is a powerful descriptor for tuning and predicting oxygen surface exchange kinetics on mixed conducting oxides. By infiltrating a selection of binary oxides from strongly basic (Li2O) to strongly acidic (SiO2) onto the surface of Pr0.1Ce0.9O2-δ samples, it was possible to vary the chemical surface exchange coefficient kchem by 6 orders of magnitude, with basic oxides such as Li2O increasing kchem by nearly 1,000 times, with surface concentrations as low as 50 ppm impacting kchem. Strikingly, although the pre-exponential of kchem scales linearly with the acidity of the infiltrated binary oxide, there is nearly no change in the activation energy. The origin of these dramatic changes is proposed to arise from the systematic increase in electron concentration at the Pr0.1Ce0.9O2-δ surface with the decreasing acidity of the infiltrated binary oxide. [Figure not available: see fulltext.]",

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AU - Yildiz, Bilge

AU - Tuller, Harry L.

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N2 - Improving the kinetics of O2 reduction on oxide surfaces is critical in many energy and fuel conversion technologies. Here we show that the acidity scale for binary oxides is a powerful descriptor for tuning and predicting oxygen surface exchange kinetics on mixed conducting oxides. By infiltrating a selection of binary oxides from strongly basic (Li2O) to strongly acidic (SiO2) onto the surface of Pr0.1Ce0.9O2-δ samples, it was possible to vary the chemical surface exchange coefficient kchem by 6 orders of magnitude, with basic oxides such as Li2O increasing kchem by nearly 1,000 times, with surface concentrations as low as 50 ppm impacting kchem. Strikingly, although the pre-exponential of kchem scales linearly with the acidity of the infiltrated binary oxide, there is nearly no change in the activation energy. The origin of these dramatic changes is proposed to arise from the systematic increase in electron concentration at the Pr0.1Ce0.9O2-δ surface with the decreasing acidity of the infiltrated binary oxide. [Figure not available: see fulltext.]

AB - Improving the kinetics of O2 reduction on oxide surfaces is critical in many energy and fuel conversion technologies. Here we show that the acidity scale for binary oxides is a powerful descriptor for tuning and predicting oxygen surface exchange kinetics on mixed conducting oxides. By infiltrating a selection of binary oxides from strongly basic (Li2O) to strongly acidic (SiO2) onto the surface of Pr0.1Ce0.9O2-δ samples, it was possible to vary the chemical surface exchange coefficient kchem by 6 orders of magnitude, with basic oxides such as Li2O increasing kchem by nearly 1,000 times, with surface concentrations as low as 50 ppm impacting kchem. Strikingly, although the pre-exponential of kchem scales linearly with the acidity of the infiltrated binary oxide, there is nearly no change in the activation energy. The origin of these dramatic changes is proposed to arise from the systematic increase in electron concentration at the Pr0.1Ce0.9O2-δ surface with the decreasing acidity of the infiltrated binary oxide. [Figure not available: see fulltext.]

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Acidity of surface-infiltrated binary oxides as a sensitive descriptor of oxygen exchange kinetics in mixed conducting oxides

Abstract

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