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 st ability of BICUVOX.10 is an important factor fdr its future application. Th e electrochemical reduction and oxidation can be recognized very easily by the voltammetric technique. Our previous voltammetric measurements were mad e on 3-electrode cells like Pt,O-2\BICUVOX.10\O-2,Pt using BICUVOX.10\O-2,P t as reference electrode. This investigation showed a reduction of the mate rial in the cathodic scan, followed by an oxidation peak in the anodic one. However, a quantitative elucidation of the reduction processes was not pos sible. The use of small samples in a cell of the arrangement Pt,Ar\sample\Y SZ\Ar,Pt allows to distinguish between different reduction steps during the negative sweep. The reference electrode was a platinum point electrode app lied to YSZ. Because of the small size of a sample it can be reduced to a l arge extent at temperatures above 600 degrees C. We found that the sample s tarted to be reduced irreversibly below -570 mV against the reversible oxyg en 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 subse quent cycles showed reversible reduction and oxidation of the residual oxid es. (C) 1998 Published by Elsevier Science B.V. All rights reserved.