Non-Faradaic electrochemical modification of catalytic activity
Journal Article
·
· Journal of Catalysis
OSTI ID:263785
- Univ. of Patras (Greece)
The catalytic activity of Pt for the oxidation of ethylene to CO{sub 2} can be markedly and reversibly affected by interfacing polycrystalline Pt films with TiO{sub 2} and applying currents or potentials between the catalyst film and a Au counter electrode at temperatures near 500{degrees}C. The increase in the rate of C{sub 2}H{sub 4} oxidation is up to 20 times higher that the open-circuit (unpromoted) catalytic rate and at least a factor of 5000 higher than the rate of O{sup 2-} supply through the mixed conducting TiO{sub 2} support. The latter is and remains catalytically inert during electrical bias. This electrochemically induced Schwab effect of the second kind has all the same qualitative features with the effect of non-Faradaic electrochemical modification of catalytic activity (NEMCA effect) when using pure O{sup 2-} conductors. Work function measurements and X-ray photo-electron spectroscopic (XPS) investigation of the Pt catalyst surface under UHV conditions has also provided evidence consistent with the electrochemically controlled promoting oxide ion backspillover mechanism which is operative with NEMCA when using pure O{sup 2-} conductors. Under reaction conditions in atmospheric pressure or oxidizing environments in UHV the TiO{sub 2} support exhibits mixed electronic (n-type)-ionic conductivity and thus the catalyst work function and catalytic activity can be controlled by the applied potential. In reducing environments the electronic conductivity of TiO{sub 2} dominates and the catalyst work function remains constant upon application of potential. 44 refs., 18 figs.
- OSTI ID:
- 263785
- Journal Information:
- Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 1 Vol. 159; ISSN 0021-9517; ISSN JCTLA5
- Country of Publication:
- United States
- Language:
- English
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