Glass-Coated Mixed Conducting Cobaltites as Solid-Reference Electrode Materials for NASICON-Based Potentiometric CO2 Sensors

Abstract

To improve the stability of (NASICON)-based potentiometric sensors fitted with carbonate/Au layers (sensing electrode), mixed conducting oxides of and were examined for their applicability to solid-reference electrodes in terms of their stability against and humidity. Compared with the electrode, the electrode showed far better stability against . When the electrode was coated with a layer of glass, the electrode showed no response to (200–2000 ppm) and little interference from humidity [21–86% relative humidity (RH)] at . A sensor device using and a glass-coated showed stable electromotive force (emf) responses to in humid air (86% RH) at . The emf of the device was also stable even after it was exposed to humid air (86% RH) containing (400 ppm) at room temperature for 1–2 days. The present study indicates the promising features of the glass-coated as a stable solid-reference material for NASICON-based sensors.