Effect of heat treatment on WO3 nanostructures based NO2 gas sensor low-cost device

Abstract

This study introduces an elaboration of the heat treatment influence on the morphological, structural, and gas sensing performance of Tungsten trioxide. It has been coated by pulsed laser technique (PLT) using optimized conditions. The optimum crystalline size and surface area have been observed at (750 °C) of heat treatment with values of 47.81 nm and 20.45 m2/g, respectively. The surface morphology of Tungsten trioxide depicted that the shape of film has bunches of grapes-like structure with a high number of pores which is the perfect one for the sensing performance. The higher surface roughness investigated by AFM makes it more active for the gas molecules. The electronic structure analysis confirmed the presence of oxygen vacancies which provide a lot of sites for the gas molecules. The gas-sensing performance towards the (NO2) molecules has been measured, and it was found that the film sensor revealed an ultra-gas response at the room temperature with a value of (392%) for the gas concentration of (150) ppm. Furthermore, the limit of detection manifested that the device can detect the minimum value concentration of (1.72 ppm) NO2 gas molecules at the room temperature. Besides, WO3 nanostructures have high selectivity, stability, and reproducibility to the NO2 toxic gas.