Synthesis, Properties And Device Study Of The One-dimensional MoO₃Nanomaterials

Gas sensors are widely used in daily life, but the applications of traditional gas sensor were limited due to the large volume, heavy weight and poor flexibility. With the improvement of living standards, people hope sensor can realize integration, miniaturization and intelligent features. One-dimensional nanomaterials were effectively applied in the electronic transmission, preparation of nano functional due to their excellent physical and chemical properties. In recent years, one-dimensional nanomaterials have a promising future in the application of gas sensors, but compared with other metal oxides, MoO3one-dimensional nanomaterials in gas sensor applications still stay in research stage currently. Taking the advantage of the unique layered structure, MoO3has been suggested as a promising candidate for gas sensors. One-dimensional nanomaterials have great application potential in the field of gas sensor due to its large specific surface, the electrons transporting along the axis area and convenient for making flexible or smart devices. To further study the gas sensing performance of one-dimensional MoO3nanomaterials, MoO3nanobelts were obtained via hydrothermal process using two different precursors in this dissertation. The structures and morphologies of the samples were investigated by modern test methods, and the gas sensing property of the products was also studied.1. The peroxo-polymolybdic acid and metallo-organic compound were used as the precursor. And the products were orthorhombic MoO3nanobelts with10μm in length,100～250nm in diameter and20～50nm in thickness via hydrothermal process using peroxo-polymolybdic acid as the precursor. And the products were nanobelts with100～300μm in length,100nm～1μm in diameter and50～500nm in thickness via hydrothermal process using metallo-organic compound as the precursor, a single nanobelt would be separate from the product when the hydrothermal time reach25h.2. The MoO3nanobelts were made into devices and their gas sensing properties for ethanol were studied. The working temperature of MoO3nanobelts prepared using the peroxo-polymolybdic acid as the precursor is150～332℃and the highest sensitivity is33to1000ppm ethanol gas obtained at the temperature of190℃, the detecting limit is20ppm at this temperature. And the working temperature of MoO3nanobelts prepared using the metallo-organic compound as the precursor is150～332℃and the highest sensitivity is13to1000ppm ethanol gas obtained at the temperature of273℃, the detecting limit is5ppm above this temperature.3. The devices based on single nanobelt prepared using the metallo-organic compound as the precursor was made, and studied its electrical and gas sensing properties. It was found that device prepared using Si/SiO2substrate which the thickness of SiO2is more than300nm, metal electrode which work function was less than5.5ev and thinner nanobelt could have ohmic contact with testing voltage rang from-1～+1V. The results showed that the device based on single nanowire had a good response to ethanol. Results show that the response time and recover time of the sensor based on single nanowire to1000ppm ethanol is only10s and2s, to4000ppm ethanol is only3s and3s.