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

摘要

LaNbO4 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 LaNbO4 electrodes sintered at different temperatures showed basically no obvious difference, while the porous network and the most TPB sites were obtained at 1100 degrees 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 degrees C, and polarization and EIS measurements were then evaluated for the analysis of response mechanism. Moreover, the slight sensitivities to interfering gases like NOx 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, LaNbO4 is promising in monitoring CO as a sensing material adopted by potentiometric sensor.

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