NOx Sensing with n-type WO3 - CuWO4 Composites

Abstract

Thin-films of WO3 : CuWO4 composites were used as sensing materials for NO monitoring. The thin-films were prepared by the pulsed laser deposition technique using formulations with molar ratio spanning from 1 to 0. The sensing films were characterized by depth-profilometry, X-ray diffraction (XRD) and electron transport measurements. The transduction mechanism and its relation to the chemical surroundings, including temperature effects, were studied by monitoring the changes in electronic conductance (resistance) with temperature, gas-phase analyte chemical nature and concentration. Sensor performance studies were carried out. It was found that the best sensing material was composed of a nanometric layer of CuWO4. This formulation offers fast response and short recovery times towards both O2 and NO, with a response proportional to analyte concentration and excellent reproducibility.