Visible and UV photocatalytic characterization of Sn–TiO2 electrospun fibers

Nanostructured fiber-mats have large surface area, high reactivity, low weight and low agglomeration tendency. These are advantages if compared with nanoparticles for photocatalytic application. In this work, high temperature stable anatase titanium dioxide fiber-mats doped with tin (0.5–15%) were produced by electrospinning technology. The precursors used were titanium propoxide (TiP) and Tin 2-ethylhexanoate. They were hydrolyzed in acetic acid and mixed with an alcoholic solution of 10 wt.% PVP. The effect of heat treatment on the microstructure characteristics and the photocatalytic activity of the fiber-mats in comparison with a commercial TiO2 powder (Degussa P-25) were studied. After the electrospinning process, a thin, porous fiber-mat was obtained. This material was dried in air at room temperature for 24 h. These fibers were then heat treated from 450 to 800 °C for 3 h at a heating rate of 1.4 °C/min. The fiber-mats were then, characterized using N2 adsorption – BET surface area, X-ray diffraction for crystalline phase determination, and SEM and TEM analyses for morphological characterization. The photocatalytic properties were studied using as model system the degradation of methyl orange in water (20 ppm) under UV-A or visible light. The results show that the photoactivity increases with the increment in heat treatment temperature until 650 °C, when the fibers start to become densified and the surface area drops significantly due to sintering. The addition of Sn was beneficial to the photoactivity of TiO2 fibers.