High response methane sensor based on Au-modified hierarchical porous nanosheets-assembled ZnO microspheres

Detecting methane (CH4) gas is very important owing to its widely use as a fossil fuel with an explosive hazard in modern society. In this study, a CH4 gas sensor was prepared, which is based on hierarchical porous nanosheets-assembled Au/ZnO microspheres with diameters of 10-12 mu m. X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) were used to characterize the textural properties and morphology of the nanocomposites. In addition, the gas sensing properties of the sensors basedon pure ZnO and Au/ZnO nanomaterials were systematically investigated. By modifier Au nanoparticles, the characteristics of ZnO based sensor for CH4 detection were significantly enhanced. Especially, the Au/ZnO based sensor with an Au content of 1.0 at.% exhibited the best sensing performances (4.16) of 100 ppm CH4 at 250 degrees C. Furthermore the sensor also exhibited a good linear relation (10-2000 ppm CH4 concentration), excellent repeatability, satisfactory stability and a low detection limit of detection (1.83 ppm). The possible enhanced sensing mechanism could be attributed to the synergism between the unique hierarchical porous nanosheets-assembled microspheres structure and the sensitizing actions utilized by the Au nanoparticles.