Fabrication of TiO2/ZnO composite nanofibers by electrospinning and their photocatalytic property

TiO2/ZnO composite nanofibers with diameters in the range of 85–200 nm were fabricated via the electrospinning technique using zinc acetate and titanium tetra-isopropoxide as precursors, cellulose acetate as the fiber template, and N,N-dimethylformamide/acetone 1:2 (v/v) mixtures as the co-solvent. After treated with 0.1 mol/L NaOH aqueous solution, TiO2/zinc acetate/cellulose acetate composite nanofibers were transformed into TiO2/Zn(OH)2/cellulose composite nanofibers. TiO2/ZnO composite nanofibers were obtained by calcinating the hydrolyzed composite fibers at 500 and 700 °C for 5 h. The structure and morphology of composite nanofibers were characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. With the blending of ZnO into TiO2, a new crystallite ZnTiO3 was formed in addition to the ZnO and TiO2 crystallites, and the ultraviolet light absorption efficiency was enhanced according to the UV–vis diffuse reflectance spectroscopy. The photocatalytic activity of TiO2/ZnO composite nanofibers toward the decomposition of Rhodamine B and phenol was investigated. Almost 100% Rhodamine B and 85% phenol were decomposed in the presence of TiO2/ZnO composite nanofibers under mild conditions. The results demonstrated that the blending of ZnO in the TiO2/ZnO composite nanofibers increased the photocatalytic efficiency. The optimum ZnO content in the TiO2/ZnO composite nanofibers was 15.76 wt% to reach the most efficient photocatalytic activity. A schematic diagram of photocatalytic mechanism of TiO2/ZnO composite nanofibers was also presented.