Effect of Particle Sizes on the Impedance of Electrospun Tungsten Oxide Nanofibers

This work presents the fabrication and the impedance spectroscopy characterization of WO3 nanofibers produced by an electrospinning technique. WO3 nanofibers consisting of various particle sizes are obtained by adjusting synthesis parameters. We highlight the influence of nanoparticle sizes on electrical resistances of electrospun nanofibers. It is found that nanofibers with small particle size have significantly high electrical resistance at the grain boundary. This is due to a significant spanning of the electron-depletion layer as compared to the size of the conduction channel in the structure. The grain boundary resistances of nanofibers with larger particle sizes have shown to be independent of the sizes of nanoparticles. To obtain ultra-sensitive gas sensors, producing nanofibers with restrictedly small particle sizes is a key, since large changes in electrical resistances can take place upon reacting with target gas molecules.