Improving methane gas sensing performance of flower-like SnO decorated by WO nanoplates.

The three-dimensional (3D) hierarchical WO-SnO nanoflowers (NFs) composites were successfully synthesized via a simple impregnation method by using WO and SnO 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 N sorption. These results indicated that SnO and WO-SnO 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 WO-SnO nanocomposites possess better methane sensing properties than that of pure SnO. The modification of WO nanoplates reduces the optimum working temperature of SnO based sensor from 120 °C to 110 °C, the response of WO-SnO based sensor to 500 ppm methane at 110 °C is 2.3 times of that of pure SnO based sensor. In addition, the WO-SnO 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.