Preparation and photocatalytic property of mesoporous ZnO/SnO2 composite nanofibers

In this paper, we prepared mesoporous ZnO/SnO2 composite nanofibers via the electrospinning technique using zinc acetate (Zn(OAc)2) and stannic chloride pentahydrate (SnCl4·5H2O) as precursors, cellulose acetate (CA) as the fiber template, and N,N-dimethylformamide (DMF)/acetone (1:1, v/v) as the co-solvent. The structure and morphology of composite nanofibers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), UV–vis diffuse reflectance spectroscopy (DRS) and nitrogen adsorption–desorption isotherm analysis. TEM images showed that the mesoporous ZnO/SnO2 composite nanofibers were composed of grain-like nanoparticles. The nanoparticles size increased with the increasing of the calcination temperature from 500 to 900 °C. Moreover, the crystal phases, grain sizes, and band gap energy of the mesoporous ZnO/SnO2 composite nanofibers were influenced by the molar ratio of Zn:Sn and the calcination temperatures. The photocatalytic activity of the mesoporous ZnO/SnO2 composite nanofibers toward the decomposition of Rhodamine B (RhB) was investigated. It was found that the photocatalytic activity of the mesoporous ZnO/SnO2 composite nanofibers was dependant on their surface areas, light utilization efficiency, and the separation of photogenerated electron/hole pairs. The maximum photocatalytic activity was shown for composite nanofibers with the molar ratio of Zn:Sn = 2:1 and calcination at 500 °C for 5 h, more or less Zn:Sn ratios lowered the photocatalytic efficiency. A mechanism of the charge separation and photocatalytic reaction for the mesoporous ZnO/SnO2 composite nanofibers was also presented.