Fast initializing solid state electrochemical carbon dioxide sensor fabricated by a tape casting technique using yttria stabilized zirconia and sodium beta alumina heterojunction

摘要

Solid-state bi-electrolyte carbon dioxide sensors with an yttira stabilized zirconia (YSZ) and sodium beta alumina (NBA) heterojunction were fabricated using the tape casting method to measure CO_2 concentrations in the air. The enhanced interface between NBA, expressed by (1 +x) Na_2O·11 Al_2O_3 and YSZ was made by the liquid phase sintering method while varying the ratio of Na_2O/Al_2O_3 from x = 0 to x=0.6. YSZ/Pt electrode was used as an air reference, maintaining a constant oxygen concentration of 21%, and Na_2Co_3 was used as a CO_2 sensing electrode. The responses of the sensors to various concentrations of CO_2 were evaluated at temperatures ranging from 550℃ to 650℃. The electric potential difference of the sensors exhibited Nernstian behavior with sensitivity greater than 99% of the theoretical value at 650 ℃. The activity of Na20 at the bi-electrolyte junction remained constant, showing invariance with the CO_2 concentrations tested. The time for the initial stabilization was as short as 66 s.