ZnO Hollow Nanofibers: Fabrication from Facile Single Capillary Electrospinning and Applications in Gas Sensors

In this work, ZnO hollow nanofibers with diameters of 120−150 nm were successfully fabricated by electrospinning the precursor solution consisting of polyacrylonitrile (PAN), polyvinylpyrrolidone (PVP), and zinc acetate composite through a facile single capillary, followed by thermal decomposition for removal of the above polymers from the precursor fibers. The as-prepared nanofibers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), resonant Raman spectra, thermal gravimetric and differential thermal analysis (TG-DTA), and Fourier transform infrared spectroscopy (FT-IR) spectra, respectively. The results indicated that, during the electrospinning process, there occurred phase separation between the electrospun composite materials, while the obtained precursor nanofibers of PAN, PVP, and zinc acetate composite might possess a core−shell structure (PAN as the core and PVP/zinc acetate composite as the shell). Furthermore, the composite nanofibers with core/shell structure could play a structural directing template role for preparing ZnO hollow nanofibers during the calcination process. The ZnO hollow nanofibers exhibited excellent sensing properties against ethanol due to their special one-dimensional nanostructural properties.