Design of nanostructured WO3·0.33H2O via combination of ultrasonic spray nozzle and microwave-assisted hydrothermal methods for enhancing isopropanol gas sensing at room temperature

Abstract

Hierarchical WO3·0.33H2O nanocolumns were prepared by a simple combination of ultrasonic spray nozzle (USN) and microwave-assisted hydrothermal (MAH) methods. The USN step promoted a high nucleation rate of H2WO4 clusters, while glycine played an important role in the crystal growth in a preferred direction. The MAH step was responsible for the crystallization of the single orthorhombic WO3·0.33H2O phase and the self-assembly of the hierarchical structure. The as-prepared sample was tested as a volatile organic compound (VOC) sensor at room temperature (22 °C) and wet conditions. Enhanced isopropanol sensitivity and selectivity were achieved due to the high specific surface area provided by the combination of USN and MAH methods. Thus, this synthesis strategy is a promising approach for fabricating different gas sensing devices.