Stabilized zirconia-based selective NO2 sensor using sol-gel derived Nb2O5 sensing-electrode

Niobium pentoxide (Nb2O5) powder was synthesized by citrate-based sol-gel method using niobium pentachloride as precursor and citric acid as gelling agent. The synthesized powder was characterized by X-ray diffraction (XRD), Fourier transformed infra-red spectroscopy (FT-IR) and scanning electron microscope (SEM). Yttria-stabilized zirconia (YSZ)-based electrochemical sensor was fabricated using the Nb2O5 powder as sensing electrode (SE) and Pt as reference electrode (RE), and its sensing characteristics were examined in the temperature range of 750-850 degrees C under each of various O-2 concentrations (5, 10, 15 and 21 vol%). It was observed that the YSZ-based sensor attached with Nb2O5-SE exhibited selective and sensitive response to NO2 at 800 degrees C in all the measured O-2 concentrations. The sensor showed the highest sensitivity and selectivity to NO2 in 5 vol% O-2. The NO2 sensing mechanism of the present sensor was confirmed to be mixed potential-type. The sensor exhibited stable response to NO2 for the examined period of more than a month. (C) 2016 Elsevier B.V. All rights reserved.