Papers by Author: Wen Ma

Abstract: Ag/TiO₂ nanofibers were obtained by sol-gel method combined with uniaxial electrospinning. The effects of different sintering temperatures (400°C, 500°C, 600°C) and different concentrations of silver (0 wt%, 0.5 wt%, 1.0 wt%, 1.5 wt%) on photocatalytic activity of TiO₂ were investigated. The morphology and interface interaction of the Ag/TiO₂ composites were investigated by SEM, TEM, XRD and UV-visible spectrophotometer. The experimental results showed that the diameter of the fiber sintered at 400°C is about 120 nm and the fiber is composed of 10-20 nm small particles. The degradation rate of methylene blue was 71% for the Ag/TiO₂ composites fiber with 1.0wt% silver and sintered at 400°C.

Abstract: The PVP+Ti (OC₄H₉)₄+SnCl₄·5H₂O/sesame oil composite fibers were successfully prepared by a sol-gel method combined with a coaxial electrospinning technique. The Sn⁴⁺/TiO₂ nanotubes were obtained by calcining the above-mentioned composite fibers and characterized by XRD and TEM. XRD results show that increasing reaction temperature facilitates to form a stable phase. TEM results show that the Sn⁴⁺/TiO₂ nanotubes have smooth surface with wall thickness of ~120 nm and are composed of small particles of ~5 nm. The photocatalytic activity of Sn⁴⁺/TiO₂ nanotubes was investigated. The photodegradation efficiency of Sn⁴⁺/TiO₂ nanotubes decreases in UV region but increases in visible light region. The photocatalytic properties of three 0.52at% Sn⁴⁺/TiO₂ nanomaterials with different morphologies were also evaluated. The photodegradation efficiencies of Sn⁴⁺/TiO₂ nanopowers, Sn⁴⁺/TiO₂ nanofibers and Sn⁴⁺/TiO₂ nanotubes increase in visible light region in sequence. In summary, chemical modification by doping Sn⁴⁺ and morphology changing for TiO₂ can improve its photocatalytic activity in visible light region significantly.

Abstract: TiO₂ nano powder doping with Sn⁴⁺ was directly synthesized by a low temperature hydrothermal method using tetrabutyl titanate (TBOT) as a Ti resource and NH₄Cl as a dispersant. The synthesized nano powder was characterized by XRD, BET, TEM and EDS analyses. XRD results show that increasing reaction temperature facilitates to form a stable phase, and the synthesized nano power size is uniform with particle size of 10-20 nm. Doping Sn⁴⁺ ion does not result in an obvious lattice distortion. The effect of doping Sn⁴⁺ ion on photocatalytic activity in visible light region for modified TiO₂ was investigated by degrading methylene blue solution.