EIS Studies of Porous Oxygen Electrodes with Discrete Particles: I. Impedance of Oxide Catalyst Supports

Guoying Chen; Chad C. Waraksa; Hungoo Cho; Digby D. Macdonald; Thomas E. Mallouk

doi:10.1149/1.1594729

EIS Studies of Porous Oxygen Electrodes with Discrete Particles: I. Impedance of Oxide Catalyst Supports

Guoying Chen, Chad C. Waraksa, Hungoo Cho, Digby D. Macdonald, Thomas E. Mallouk

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

63 Scopus citations

Abstract

Two titanium oxide catalyst supports for the oxygen electrode of unitized regenerative fuel cells were compared by electrochemical impedance spectroscopy (EIS) techniques. One was a commercial Ebonex sample, which is a mixture of Ti₄O₇ and other conductive Magneli phases, and the other was a niobium-doped rutile oxide, Ti_0.9Nb_0.1O ₂. Both supports were loaded with a mixed Ir-Ru-Pt oxide catalyst and conditioned anodically. The impedance spectra shows a resistive component which can be assigned, using transmission line modeling of the catalyst/support/electrode structure, to the series resistance of the support particles. Although both supports increase in resistance with anodic conditioning, the increase is greater for Ebonex. This increase in support resistance is consistent with oxidation of Ti^III to Ti^IV, which appears to be reversible in the case of the Nb-doped rutile material but irreversible with Ebonex.

Original language	English (US)
Pages (from-to)	E423-E428
Journal	Journal of the Electrochemical Society
Volume	150
Issue number	9
DOIs	https://doi.org/10.1149/1.1594729
State	Published - Sep 2003

All Science Journal Classification (ASJC) codes

Electronic, Optical and Magnetic Materials
Renewable Energy, Sustainability and the Environment
Surfaces, Coatings and Films
Electrochemistry
Materials Chemistry

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title = "EIS Studies of Porous Oxygen Electrodes with Discrete Particles: I. Impedance of Oxide Catalyst Supports",

abstract = "Two titanium oxide catalyst supports for the oxygen electrode of unitized regenerative fuel cells were compared by electrochemical impedance spectroscopy (EIS) techniques. One was a commercial Ebonex sample, which is a mixture of Ti4O7 and other conductive Magneli phases, and the other was a niobium-doped rutile oxide, Ti0.9Nb0.1O 2. Both supports were loaded with a mixed Ir-Ru-Pt oxide catalyst and conditioned anodically. The impedance spectra shows a resistive component which can be assigned, using transmission line modeling of the catalyst/support/electrode structure, to the series resistance of the support particles. Although both supports increase in resistance with anodic conditioning, the increase is greater for Ebonex. This increase in support resistance is consistent with oxidation of TiIII to TiIV, which appears to be reversible in the case of the Nb-doped rutile material but irreversible with Ebonex.",

author = "Guoying Chen and Waraksa, {Chad C.} and Hungoo Cho and Macdonald, {Digby D.} and Mallouk, {Thomas E.}",

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AU - Macdonald, Digby D.

AU - Mallouk, Thomas E.

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AB - Two titanium oxide catalyst supports for the oxygen electrode of unitized regenerative fuel cells were compared by electrochemical impedance spectroscopy (EIS) techniques. One was a commercial Ebonex sample, which is a mixture of Ti4O7 and other conductive Magneli phases, and the other was a niobium-doped rutile oxide, Ti0.9Nb0.1O 2. Both supports were loaded with a mixed Ir-Ru-Pt oxide catalyst and conditioned anodically. The impedance spectra shows a resistive component which can be assigned, using transmission line modeling of the catalyst/support/electrode structure, to the series resistance of the support particles. Although both supports increase in resistance with anodic conditioning, the increase is greater for Ebonex. This increase in support resistance is consistent with oxidation of TiIII to TiIV, which appears to be reversible in the case of the Nb-doped rutile material but irreversible with Ebonex.

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