Hierarchically connected electrospun WO3 nanowires – An acetaldehyde sensor

Abstract Hierarchically connected low-dimensional metal oxide nanostructures have been preferred to fabricate gas-sensing elements owing to their enhanced sensing response. In this juncture, hierarchical architectures of WO3 nanowires were synthesized using electrospinning technique with polyvinyl alcohol and ammonium metatungstate hydrate as precursor. X-ray diffraction analysis revealed the polymer evaporation and metal oxide formation with phase transformation of WO3 nanowires from monoclinic to orthorhombic and back to monoclinic as an effect of calcination temperatures (673–973 K). The variation in the interconnected grain features of WO3 nanowires as a function of calcination temperature was observed using field emission scanning electron microscope and transmission electron microscope. The formation of higher oxidation states of tungsten (W6+) and increased oxygen vacancies were observed for the samples calcined at higher temperatures through X-ray photoelectron spectrometer. Electrical studies for 873 K sample showed the maximum mobility of electrons due to the highly interconnected nanowires with minimum grain boundary resistance. The gas sensing responses of WO3 nanostructures were investigated and WO3 sample calcined at 873 K with maximum mobility showed a selective response of 5537 towards 75 ppm of acetaldehyde at room temperature.