WO₃-based Semiconducting Nanofibers Prepared By Electrospinning Method And Their Gas Sensing Properties

Metal-oxide semiconductor gas sensor has advantages of high sensitivity, fastresponse, small size, low energy consumption and costs, and easy to operate.Electrospinning technique is easy to operate and can produce continuous nanofibers.In this study, WO₃-based nanofiber gas-sensing materials were prepared byelectrospinning method. The electrospinning process and sintering procedure werediscussed. Finally, we discussed the influence of dopant Co₂O₃and CuO, surfacemodifier Ag nanoparticles, cooling way, and the sensor’s selectivity to acetone.WO₃-based sol was prepared by using H₂WO₄, Co（NO₃）26H₂O andCu（NO₃）23H₂O as raw materials, citric acid as chelating agent, ethanol as solvent,and H₂O2as dispersant. WO₃nanofibers were prepared using electrospinning method.Indirectly heated sensors were prepared after sintering at500℃, which were used forgas sensing measurement.In this study, WO₃nanofibers with controllable diameters and crystallitiy wereprepared by electrospinning technique, combined with sol-gel method and reasonablesintering procedure. According to our results, pure WO₃nanofibers have smalldiameters （¹00nm）, and the membrane exhibits a certain degree of porosity. Whendoping with cobalt, the nanofibers have smaller diameter, and the copper dopingresulted in hollow structures. Besides, the crystal structure of WO₃can be controlledthrough quench method.3mol%Cu-doped WO₃nanofibers （quench） exhibit bestacetone sensing properties; the sensitivity to20ppm acetone attained6.43. Agnanoparticles were linked onto the surface of WO₃nanofibers, and the sensors showgood response to acetone gas.The acetone sensing selective mechanism was also discussed. It was found thation doping and changing heat treatment can influence the diameter, microstructureand crystal structure of WO₃nanofibers. It is more important to control phasestructure than just reduce the nanofibers’ diameters. In this research,3mol%Cu-doped WO₃nanofibers （quench） exhibit high sensitivity and good selectivity toacetone, this is mainly attributed to its triclinic and orthorhombic phase structures,which has lowest symmetry and largest dipole moment. Therefore, the research ofWO₃-based nanofiber gas sensing materials has lay the foundation of environmentalmonitoring, food quality testing, and especially the application of breath diagnose.