Potentiometric sensor based on NASICON and In2O3 for detection of CO2 at room temperature - modification with foreign substances

In an attempt to improve the CO2 sensing properties of NASICON (Na+ conduct or)-based potentiometric device attached with In2O3 at room temperature, Na 3PO4, NaHCO3 and Na2CO3 were introduced as single-components or combination s in the CO2 sensing layer of the device. Although, the original device suf fered disturbance by humidity seriously, the disturbance could be reduced e ffectively, in some case almost completely, in the resulting modified devic es, while the sensitivity to CO2 could be even promoted. The best device ob tained, for which both of Na3PO4 and NaHCO3 were introduced, showed fairly excellent sensing characteristics, i.e. high sensitivity to CO2 and high re sistance to disturbance by humidity at 30 degreesC. The emf of the device w as linear to the logarithm of CO2 concentration in the range 300-3000 ppm f ollowing well the Nernst equation for a 1.2 electron-reduction of CO2. (C) 2001 Elsevier Science B.V. All rights reserved.