Switching effect at a platinum electrode on stabilized zirconia during oxygen reduction in the presence of NO |
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Authors: | S I Somov G Reinhardt H -D Wiemhöfer W Göpel |
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Institution: | (1) Institute of High Temperature Electrochemistry, Ekaterinburg, Russia;(2) Institute of Physical and Theoretical Chemistry, Tübingen, Germany |
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Abstract: | A galvanic cell based upon the use of stabilized zirconia as solid oxygen ion conductor has been used to measure cathodic
reduction currents at a porous platinum electrode in both nitrogen-oxygen gas mixtures with and without small amounts of NO
(up to 5450 ppm).
Adding small amounts of NO to the N2/O2 mixture induced a considerable cathodic current peak at the working electrode in the first moment after addition. After interruption
of the NO exposure, the opposite effect, a high current pulse in anodic direction, was observed. The switching effect is reproducible
and its magnitude depends on the concentrations of oxygen and nitrogen monoxide in the gas.
As the main contribution to the current results from the reduction of the excess oxygen in the gas, it must be concluded that
the presence of NO strongly affects the steady state, in particular the adsorbed oxygen at the electrode/electrolyte interface.
These experimental results are interpreted in terms of a reversible change of the interface which may be due to a reconstruction
of the platinum surface in the presence of NO and corresponding drastic change in the amount of adsorbed oxygen at the platinum
surface.
Paper presented at the 1st Euroconference on Solid State Ionics, Zakynthos, Greece, 11 – 18 Sept. 1994 |
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