Preparation, Modification And Of Gas Sensing Properties WO_x Nanomaterials

Tungsten oxides (WOx) are one of multifunctional inorganic semiconducting metal oxides. As the new sensing materials, WOx based gas sensors have been widely used in various fields due to their advantageous features. WO3 and W18O49 are common tungsten oxides materials. Their special crystal structures make them have the potential of gas sensitive detection. WO3 nanotubes, WO3 nanosheets and W18O49 nanofibers are prepared three different crystal structures, then studying on the gas sensing properties. Therefore, the experiment results show that the selectivity and sensitivity should -be improved. The experiment chooses graphene as doped material. We hope that with the help of its fast electron transfer the gas sensing properties of WOx can be improved.1、Preparing WO3 nanotubes using the solvothermal treatment method, and the WO3 has high specific surface area of 34.61m2/g. To modify WO3 with graphene, the experiment results shows that the best operating temperature is 340℃ and the sensitivity is not saturated with increasing gas concentration. The test results show that the sensitivity of graphene-doped WO3 gas sensors is much higher than pure WO3 gas sensor, especially graphene-doped WO3 to ethanol is more than two times to pure WO3,which sensitivity is up to 13.1.2、In the experiment, the sensitivity of synthesized WO3 nanosheets with the NH4+-based EDTA sample was tested. The response of the gas sensor is rapid and the time of recovery is short, but the results of sensitivity are not desirable. To modify WO3 with grapheme, the test results show that response - the recovery time still very short. Under the best operating temperature 300℃,graphene-doped WO3 sensitivity to ethanol is up to 14.88, which is more than two times to pure WO3,and has the potential of ethanol gas detection.3、Preparing W18O49 nanofibers using hydro-thermal treatment method. Compared with pure W18O49, the best operating temperature of graphene-doped W18O49 is reduced to 340℃. In addition, the test results show that graphene do improve the sensitivity of W18O49, its sensitivity to ethanol is more than two times to pure W18O49. Graphene-doped W18O49 gas sensor shows a good selectivity to ethanol methanol. So it is obvious that doping graphene can lower W18O49 operating temperature and improve sensitivity.