Synthesis and Optical Properties of Co-Doped ZnO Submicrometer Tubes from Electrospun Fiber Templates

Submicrometer ZnO tubes have been synthesized by a polymer based template approach using sol-gel deposition. Zinc acetate, a precursor to ZnO, was deposited on catalytically active electrospun polycarbonate fibers approximately 250+/-100 nm in diameter. Thermal degradation of the core fibers resulted in the oxidation of zinc acetate to produce ZnO nanotubes with diameters of approximately 500+/-100 nm and an average wall thickness of approximately 100+/-50 nm. Scanning electron microscopy (SEM), Energy dispersive spectroscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy, and UV-visible spectroscopy were used to characterize the composition, structure, and morphology of the tubes. Powder X-ray diffraction results showed that a wurtzite crystalline phase was obtained. The UV-visible absorption spectrum was red-shifted by 25 nm due to narrowing of the ZnO band gap (approximately 3.22 eV) as a result of Co doping. Similarly, green band emission was not observed in the emission spectrum, while emission lifetime was determined to be 620 ps from photoluminescence studies.