New solid-state glass electrodes by using zinc oxide thin films as interface layer

Abstract

Novel glass electrodes for the determination of cations with reversible internal solid contact are introduced. They are based on a semiconducting zinc oxide layer with a maximum thickness of 1 µm in contact with ion selective glasses on one side and with a metal layer on the other side. The metal oxide layer is thereby generated either by ultrasonic spray pyrolysis from zinc acetate solution, by electrochemical deposition from zinc nitrate solution or by spin coating from a dispersion of ZnO in an organic binder. A following activation in a palladium chloride solution allows the chemical reductive deposition of NiP as electronic conductor. Dipping-type and flow through electrodes as well as planar glass electrodes in thick film technology fabricated in the above-mentioned method are described. In this case gold electrodes are applied by screen printing on isolated steel substrates. The zinc oxide layers, created in different manners, are covered afterwards with cation selective glasses in thick film technology. They cause a stabilisation of the half-cell potentials of the all solid state indicator electrodes proved by suitable measurements.