Investigation on ozone-sensing characteristics of surface sensitive hybrid rGO/WO3 nanocomposite films at ambient temperature

Abstract

Ozone-sensing characteristics of pure WO3 and hybrid rGO/WO3 nanocomposite materials synthesised by hydrothermal method were investigated. The physicochemical properties of prepared samples were studied by XRD, FTIR, Raman, HR-SEM, HR-TEM, and XPS analysis. The XRD analysis confirmed the monoclinic structure of WO3 with an average crystallite size of 22 nm and the WO3 nanoparticles were finely embedded on the surface and between the nanosheets of rGO as confirmed by SEM and TEM analysis. The XPS analysis confirms the presence of C, W, and O elements and their valence states with respect to binding energies in the rGO/WO3 nanocomposite. The prepared rGO/WO3 nanocomposites were developed as thin film with different thickness of conductive polymer matrix layer of 2, 4, and 6 μm to study the effect of thickness on the ozone-sensing characteristics of the sample. An increase of conductive layer thickness could enhance the sensing response of the hybrid rGO/WO3 nanocomposite films and exhibited better sensing performance than pure WO3 film. Moreover, the AFM studies show the formation of cavities and surface uniformity after the exposure of ozone gas. In addition, the calculated ID/IG ratio (~ 1.84) of an optimised rGO/WO3 sensing film was increased dramatically after the ozone exposure, owed to the reduction of rGO through an interaction between ozone molecules and sensing film. The experimental results suggest that the hybrid rGO/WO3 nanocomposite sensing film could be a potential candidate for sensing of ozone molecule at even low ppm level in ambient temperature.