| There is a rapid development in science and technology in recent years. And living standards of people have increased gradually. While many problems due to the rapid development have been brought to us and made us pay more and more attention, such as the environment and the ecology. So there is a chance for gas sensors to develop and also a challenge for the properties of gas sensors. WO3 is a kind of traditional gas sensing materials for testing hydrogen gas and nitrogen oxide gas. WO3 has been widely developed for its good selectivity and low cost. Electrospinning is a kind of technology to produce one-dimensional nanofibers and has a great development in recent years. In this paper, WO3 nanofibers have been prepared by electrospinning to improve the gas sensing properties.It is mainly about the production of WO3 nanofibers in the first part of this experiment. Phosphotungstic acid and tungsten chloride are used as the precursor of producing WO3 nanofibers respectively. Dimethylformamide, ethanol and deionized water are used as organic solvents. PVP has been selected as the organic compound. The electrospinning precursor solutions have been made in different contents of precursor, organic solvent and PVP. WO3/PVP composite nanofibers have been prepared finally by adjusting the different parameters of electrospinning, and the experimental conditions of exploration. And also WO3 nanofibers have been produced through different sintering temperature and sintered at different temperature gradients. Meanwhile, the composition and morphology characteristics of WO3/PVP composite nanofibers, and WO3 nanofibers have been analyzed through XRD and SEM characterization methods. It is proved that pure WO3 nanofibers have been prepared. The best content has been found by comparing different electrospinning parameters and the morphologies of WO3 nanofibers. The best content of electrospinning precursor solution of phosphotungstic acid is that: 1gH3O40PW12?xH2O+2.3gPVP +8mlDFM+2mlH2O. The best content of electrospinning precursor solution of chloride tungsten is that: 1gWCl6+2.3gPVP+3mlC2H5OH+7mlDFM. And the best sintering temperature is 500℃.The second part of this study is about the gas sensing test for NH3 of WO3 nanofibers and WO3 particles. The response of WO3 particles is 4.5 due to 100ppm NH3, the response time is 100s, and the recovery time is 400s. The response of WO3 nanofibers made by phosphorus acid as precursor is 2.5, the response time is 50s, and the recovery time is 100s. The response of WO3 nanofibers made by chloride tungsten as precursor is 5.5, the response time is 1s, and the recovery time is 5s. It can be seen that the sensitivity and the response and recovery characteristics of WO3 nanofibers made by electrspinning have been greatly improved.WO3 nanofibers have been prepared successfully in this paper. It's found that there are a great of grain boundary barrier existing in WO3 particles. And it's very easy to grow up for WO3 particles during the high-temperature sintering and high temperature testing process. So they will not only reduce the particle surface area, but also obstruct the transfer of electrons between WO3 particulates and reduce the speed of response and recovery of WO3 particles. In WO3 nanofibers made by electrospinning in this study, each nanofiber is continuous and grain boundary barrier is small. There are electronic transmission channels in WO3 nanofibers and improving the response and recovery characteristics in gas sensing test.
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