Sensitive and selective NO2 gas sensor based on WO3 nanoplates

Abstract Gas sensors based on a chemiresistive metal oxide semiconductor are widely used including nitrogen dioxide (NO 2 ) at a moderate temperature. In this work efforts are taken to fabricate NO 2 gas sensor using thin films of tungsten oxide (WO 3 ) grown directly on to a soda-lime glass substrate without assistance of any seed layer by a simple and a facile hydrothermal technique. As per our knowledge, the deposition of nanostructured WO 3 thin films without assistance of any seed layer on the glass substrate was rarely reported. The WO 3 thin film samples were synthesized at various deposition times ranging from 3 h to 7 h and were characterized by X-ray diffraction, Raman spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, UV–vis spectroscopy and Brunauer-Emmett-Teller techniques. The surface morphological and structural characterization showed the two dimensional (2D) nanoplate-like structure of as synthesized WO 3 thin films with plate thickness ranging from 90 to 150 nm and had an orthorhombic structure, respectively. Moreover, the 2D nanoplates of WO 3 exhibited a gas response ∼10 for 5 ppm for toxic NO 2 gas at relatively low operating temperature. The new synthesis route and sensing behavior of as synthesized WO 3 nanoplates revealed a promising candidate for the fabrication of the cost effective gas sensors.