NASICON-based potentiometric CO2 sensor combined with new materials operative at room temperature

The improvement for the deterioration of CO2 sensing properties in lower humidity condition was attempted to a NASICON-based potentiometric CO2 device operative at room temperature. To optimize the sensing electrode, the device was fabricated by using ITO powders with a large specific surface area and by using a mixture of ITO and basic oxide powders. Although CO2 sensing properties of the device were markedly improved by applying the above ideas in lower humidity condition, it was confirmed that the basic EMF drifts with changing the humidity conditions. Further, to find out the appreciate reference electrode material, the thermal and chemical stabilities were examined by XRD measurement for three kinds of oxides such as Li0.62CoO2, Na0.6CoO2 and Li2TiO3. As the results, Na0.6CoO2 and Li2TiO3 were much stabler than Li0.62CoO2 thermally and chemically. It was also found that Li2TiO3 has a poor electric conductivity. Therefore, Na0.6CoO2 is the most suitable material for the reference electrode of the NASICON-based device operative at room temperature. (c) 2005 Elsevier B.V. All rights reserved.