LaNbO4 as an electrode material for mixed-potential CO gas sensors

LaNbO 4 powder was synthesized and first used as sensing material to fabricate potentiometric sensor in the field of carbon monoxide (CO) detecting. The XRD spectrums of LaNbO 4 electrodes sintered at different temperatures showed basically no obvious difference, while the porous network and the most TPB sites were obtained at 1100 °C, bringing the best sensing performance which includes sensitivity of −87.25 mV/decade and a swift response/recovery process within 47/52 s to 400 ppm CO. The response values all take on an approximately linear trend with logarithm of CO concentration from 50 ppm to 400 ppm, which agrees well with the mixed-potential mechanism. The sensor exhibited the most comprehensive sensing properties to CO when operating at 400 °C, and polarization and EIS measurements were then evaluated for the analysis of response mechanism. Moreover, the slight sensitivities to interfering gases like NO x indicated a good selectivity of the sensor, and the response value was also less affected by the oxygen concentration and water vapor. Given the satisfied response signal and swift response/recovery processes, good CO selectivity, adequate stability in repetitive and prolonged test, LaNbO 4 is promising in monitoring CO as a sensing material adopted by potentiometric sensor. • LaNbO 4 was firstly used as an electrode material of mixed-potential CO gas sensor. • The sensor based on LaNbO 4 electrode exhibited fast response/recovery process, excellent selectivity and long-term stability. • LaNbO 4 material has a promising application prospect in the field of CO detection in automobile exhaust.