Development of Solid Electrolyte Reference Electrode for High Temperature Water System

Abstract

A newly designed solid electrolyte internal reference electrode has been developed for electrochemical measurement in high temperature water systems. This reference electrode is composed of an yttria stabilized zirconia (YSZ) disk electrode with a sputter-deposited Ni·NiO composite film on the backside, an asbestos plug soaked with a neutral phosphate buffer solution as an internal solution and an oxidized zircaloy-4 body. The thermodynamic response of the YSZ reference electrode has been confirmed in phosphate buffer solutions (pH4.4-9.3) with an Ag/AgCl (0.1kmol·m^-3KCl) internal reference electrode at temperatures up to 523K. It was found that the potential of the YSZ reference electrode has the following linear relationship with temperature:
E_YSZ/Ni·NiO=2395-5.37T/mVvs. SHE
Using the YSZ reference electrode, the measurement of anodic polarization curves of Type 304 stainless steel in a 0.5kmol·m^-3Na₂SO₄ solution at temperatures up to 563K has been performed. Anodic polarization curves measured with the YSZ reference electrode coincided with those with the Ag/AgCl internal reference electrode in the temperature range from 473K to 563K.