Improving methane gas sensing performance of flower-like SnO2 decorated by WO3 nanoplates.

The three-dimensional (3D) hierarchical WO3-SnO2 nanoflowers (NFs) composites were successfully synthesized via a simple impregnation method by using WO3 and SnO2 prepared by hydrothermal method as precursors. The structure and morphology of the as-prepared samples were investigated by the techniques of X-ray diffraction (XRD), field-emission electron scanning microscopy (FESEM), transmission electron microscopy (TEM) and N2 sorption. These results indicated that SnO2 and WO3-SnO2 nanostructures with a diameter of about 500 nm self-assembled by numerous nanorods of about 200 nm in length. Gas sensing test results show that the nanostructure WO3-SnO2 nanocomposites possess better methane sensing properties than that of pure SnO2. The modification of WO3 nanoplates reduces the optimum working temperature of SnO2 based sensor from 120 °C to 110 °C, the response of WO3-SnO2 based sensor to 500 ppm methane at 110 °C is 2.3 times of that of pure SnO2 based sensor. In addition, the WO3-SnO2 based sensor possesses lower detection limit, good repeatability and stability. The improved gas-sensing mechanism of the nanocomposite based sensors for methane detection is also discussed in detail.