Characterization and Humidity Sensing Application of WO3-SnO2 Nanocomposite

Abstract

Studies on the sensitivity of the electrical resistance and fabrication process of SnO 2 doped WO 3 nanometer materials for sensing applications are reported in details .Other properties such as reproducibility, aging and hysteresis were also recorded and found satisfactory. The sensing mechanism was discussed based on their annealing temperature, composition, crystallite size, surface area and porosity of the sensing element. In general, at low humidity, surface area and water adsorption plays the dominant role, while at high humidity, mesopore volume and capillary condensation become important. At the annealing temperature 600°C, sample 3 weight % of SnO 2 doped WO 3 nanocomposites have been prepared through solid-state reaction route, shows average sensitivity of 18.61 MΩ/%RH in the 15%-95% RH range, lower hysteresis, less effect of ageing and high reproducibility. It was observed that as resistance of the pellets continuously decreased when relative humidity in the chamber was increased from 15% to 95%. As calculated from Scherer's formula, crystallite size for the sensing elements of SnO 2 doped WO 3 are in 11-234 nm range, respectively.