Voltammetry on BICUVOX.10 microsamples

BICUVOX.10 (Bi2Cu0.1V0.9O5.35) might be a very attractive material for use in oxygen sensors, fuel cells and oxygen separators. The electrochemical stability of BICUVOX.10 is an important factor fdr its future application. The electrochemical reduction and oxidation can be recognized very easily by the voltammetric technique. Our previous voltammetric measurements were made on 3-electrode cells like Pt,O-2\BICUVOX.10\O-2,Pt using BICUVOX.10\O-2,Pt as reference electrode. This investigation showed a reduction of the material in the cathodic scan, followed by an oxidation peak in the anodic one. However, a quantitative elucidation of the reduction processes was not possible. The use of small samples in a cell of the arrangement Pt,Ar\sample\YSZ\Ar,Pt allows to distinguish between different reduction steps during the negative sweep. The reference electrode was a platinum point electrode applied to YSZ. Because of the small size of a sample it can be reduced to a large extent at temperatures above 600 degrees C. We found that the sample started to be reduced irreversibly below -570 mV against the reversible oxygen electrode in 1 atm O-2 during the first negative sweep. Only part of the reduced sample can be reoxidised during the next positive sweep. The subsequent cycles showed reversible reduction and oxidation of the residual oxides. (C) 1998 Published by Elsevier Science B.V. All rights reserved.