Structural and optical characterization of WO3 and WO3/rGO nanocomposites synthesized by a simple chemical method

The chemical structure and morphology of inorganic metal oxides have attracted increasing interest because of these parameters directly influence their sensing properties. Additionally, the incorporation of reduced graphene oxide (rGO) favors an increase in the sensitivity of these composites. Tungsten oxide (WO3) and tungsten oxide/reduced graphene oxide (rGO) nanocomposites with 3 w% (WO3/rGO) were prepared via reflux method. X-ray Diffraction (XRD), Raman Spectroscopy and Scanning Electron Microscopy (SEM) techniques were used to study the crystalline structure and morphology properties of the prepared WO3 and WO3/rGO nanocomposites. The diffraction pattern of WO3 shows the diffraction peaks of tungsten trioxide hydrate (WO3(H2O), tungstite) with orthorhombic structure; however, with the annealing at 500 °C occur a phase transformation to the monoclinic structure. The incorporation of rGO into the WO3 matrix did not modify its monoclinic chemical structure. The crystallite size of the reduced composites increases as the percentage of rGO increases. Furthermore, the optical properties of WO3/rGO nanocomposites were characterized by Ultraviolet-Visible Diffuse Reflectance Spectroscopy (UV-Vis DRS). The band gap of WO3/rGO composites varies between 3.32 and 3.35 eV. SEM images of WO3 show structures of nanoplates with rectangular transversal section.