Mixed valent tungsten oxides: New electrode materials for the potentiometric detection of dissolved oxygen at temperatures below 35 °C
✍ Scribed by H. Kohler; W. Göpel
- Book ID
- 103960221
- Publisher
- Elsevier Science
- Year
- 1991
- Tongue
- English
- Weight
- 925 KB
- Volume
- 4
- Category
- Article
- ISSN
- 0925-4005
No coin nor oath required. For personal study only.
✦ Synopsis
WI8049 and La,W03 perovskites are promising electrode materials for application in potentiometric sensors for dissolved oxygen which operate at temperatures below 35 "C. This stimulated us to perform combined electrochemical and surface analytical investigations to understand the electrode reactions involved. The electromotive force (e.m.f.) is a mixed potential from reactions involving W0,2-and OH-ions and dissolved oxygen. The last species adsorbs reversibly at the electrode surface, thereby forming super-oxide ions. This process is catalysed by metallic surface states of an electrode layer formed in situ. The composition of this surface layer is determined by a steady-state equilibrium of reactions forming and decomposing the layer. This gives rise to the notably good reversibility and drift behaviour of the sensor. Preliminary data of a membrane-covered are also presented.