Mixed potential type ppb-level acetaldehyde gas sensor based on stabilized zirconia electrolyte and a NiTiO3 sensing electrode

An attempt has been performed to develop a selective and sensitive acetaldehyde gas sensor based on yttria-stabilized zirconia (YSZ) solid electrolyte in conjunction with NiTiO3 sensing electrodes (SEs) calcined at different temperatures (800, 1000 and 1200 degrees C). Among all the evaluated sensing devices, the sensor attached with NiTiO3-SE calcined at 1000 degrees C was found to have a maximum sensing response value of -43 mV to 50 ppm acetaldehyde and a lower detection limit of 200 ppb at an optimal working temperature of 575 degrees C. The response and recovery times of the sensing device to 50 ppm acetaldehyde were 10 and 26 s, respectively. The present sensor also exhibited a segmentally linear relationship between the Delta V values and the logarithm of acetaldehyde concentration in the range of 0.2-1 ppm and 1-200 ppm at 575. and the sensitivities were -3 mV/decade and -26.5 mV/decade. Furthermore, the developed sensor had a good selectivity, reproducibility, moisture insensitivity, as well as a high temperature stability for 20 days. On basis of the polarization-curve evaluation of the present sensor, the good agreement between the observed values and the estimated values revealed that the sensing mechanism based on mixed-potential model has been confirmed.