INVESTIGATION INTO AN IMPROVED DESIGN OF CO2 SENSOR

The open-circuit voltage (e.m.f.) of the solid-state potentiometric se nsor for CO2, Pt, P-CO2(I)/Na2CO3//Nasicon(Na+)//P-CO2(I)/Au-Pd, Pt ha s been measured at 650, 690 and 720 K as a function of the partial pre ssure of CO2 between 150 and 10 000 ppm. Nasicon is used as a solid so dium ion conductor and pure Na2CO3 is employed as an auxiliary electro de. The e.m.f. of the sensor is measured in dry and moist gas mixture containing water vapour at a partial pressure of 2.4 kPa. The measured e.m.f. of the sensor was found to be unaffected by the presence of wa ter vapour in the gas mixture. The e.m.f. of the sensor was found to b e Nemstian and was reproducible within +/-5 mV on cycling through the range of partial pressure of CO2 employed in this study.