Facile Solvothermal Synthesis and Gas Sensitivity of Graphene/WO₃ Nanocomposites

Graphene has attracted enormous attention owing to its extraordinary properties, while graphene-based nanocomposites hold promise for many applications. In this paper, we present a two-step exploitation method for preparation of graphene oxides and a facile solvothermal route for preparation of few-layer graphene nanosheets and graphene/WO₃ nanocomposites in an ethanol-distilled water medium. The as-synthesized samples were characterized by using field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HRTEM), ultraviolet-visible (UV-vis) spectroscopy, Raman spectroscopy, X-ray diffraction (XRD), thermogravimetric-differential thermal analysis (TG-DTA) and gas-sensing test. The resistivity of the thick-film gas sensors based on sandwich-like graphene/WO₃ nanocomposites can be controlled by varying the amount of graphene in the composites. Graphene/WO₃ nanocomposites with graphene content higher than 1% show fast response, high selectivity and fine sensitivity to NO_x.