Investigation On Preparation,Structure And Gas Sensing Properties Of Metal Oxides

Since gas sensors based on metal oxide semiconductor had been studied in 1962, researchers have basically resolved the problems of low sensitivity and poor selectivity of gas sensors. Recently, gas sensors have been widely used to detect or control inflammable and toxic gases. However, the commercial gas sensors have some disadvantages to overcome, such as the sensitivity non-high enough and shortage stability which caused a big limit in more spread application of the gas sensors provided with great marketable values. It is well known that zinc oxide is the earliest discovered and widely used gas sensing materials, indium oxide is the most valuable materials employed as gas sensor because of its low power consumption and relative high gas selectivity to toxic gas. Thus, we selected ZnO and In2O3 as our research objects, and systemically studied the synthesis of the materials with nanostructure, the relations of material structure, morphology component and gas sensing properties. Some progresses in improving stability and gas selectivity were gained with a view to the control of crystal shape and particle size as well as investigated results of gas sensing mechanism. The details of our research works are presented as follows:1 ZnO one-dimensional nanomaterials included nanorods and nanowires, whiskers and sub-microrods with single crystal structure, satisfactory morphology and high dispersity were synthesized by means of hydrothermal and solvothermal methods. The samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), and electron diffraction (ED). The effects of the factors such as additives, reactive temperature, reactive time on the structure and morphology of the samples were studied. The crystal growth mechanisms of ZnO nanorods, nanowires and whiskers were also suggested.2 The global, cubic, needle and rods-shaped indium oxide nanomaterials were made by chemical precipitation, micro-emulsion, ultrasonic-assisted sol-gel, hydrothermal and solvothermal processes, respectively. The crystal structures, morphology and composition of the samples are characterized by XRD, ED,SEM, TEM,HRTEM, XPS and TG-DSC. In2O3 nanocrystal can be synthesized one-step without any heating...