In the last years a strong research effort has been devoted to build new sensors based on nanostructured materials. One of the most promising devices is based on metal oxides, which are well known materials for the fabrication of thin film devices.
In this work we will present our recent results on the growth and characterization of WOx nanofibers deposited by electrospinning. This technique permits the growth of nanofibers with diameter between 50 nm to 1 µm. PMMA and WCl6 have been used as precursor to prepare the PMMA/WOx fibers at room temperature and in air atmosphere. After the synthesis these films have been annealed to allow the evaporation of the organic compounds.
The parameter influencing electrospinning process and the morphology of the fiber will be examined. Morphological, chemical and structural analyses have been performed using SEM, TEM, XPS, high spatially resolved Soft XPS, XRD. These techniques have shown the formation of WOx nanofibers, formed by small crystalline grains (20-30 nm). Using soft XPS with high spatial resolution chemical maps of the nanofibers have been acquired, while XPS us allowed to identify the chemical composition of the nanofibers.
Finally they have been tested as gas sensors, in particular for CO, H2 and NO2, monitoring the variation of the electrical resistivity during the gas exposure. These results show a very high sensitivity towards NO2, in the range of the ppb, and a good sensitivity for H2 exposure, while it seems that there is no interaction with CO.
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