The Research On Magnetic TiO₂Nanofibers And Effects Of Composite Structure Design On Photocatalysis

Nanofibers (NFs) has attracted intensive research interests due to theone-dimensional morphology, large surface area and the inner space and outer surfaceemployed to design composites. TiO2is the typical photocatalytically active materials.However, it still faces challenges of low utilization of visible light and unrecoverablerecycling after photocatalytic degradation process. Herein, we develop strategies tospace-separated integrate magnetism, heterojunctions, plasmon effects and Schottkyjunctions into TiO2NFs by designing magnetic components inside the NFs and otherfunctional units on the surface, and finally to endow the TiO2NF with magneticrecovery, visible light response and enhanced photocatalytic activity. Thephotocatalytic activity and magnetic recovery are investigated by using Rhodamine(RhB) solution as the model under the irradiation of UV, Visible light and simulatedsolar light. The results include:1. The magnetic Fe3O4@TiO2NFs are prepared by Electrospun process. Thedispersive Fe3O4@SiO2with particle size of20nm was obtained by coating the citricacid surface modified Fe3O4with SiO2shell. The Fe3O4@SiO2nanoparticles wereentrapped inside the TiO2NFs by electrospun the precursors of Fe3O4@SiO2, PVPand Tetrabutyl titanate. After heat treatment, the anatase Fe3O4@TiO2NFs withsmooth surface and diameters of100-150nm were produced. The magnetizationcurve of the Fe3O4@TiO2NFs exhibits near-zero coercivity and remanence,suggesting a superparamagnetic nature. The saturation magnetization strength was3.7234emu g-1. It can be separated and recovered by applying a contactless magneticfield. Compared with TiO2NFs, the photocatalytic activity of Fe3O4@TiO2isincreased to1.06times and1.62times under UV light and simulated solar light separately.2. The CdS nanoparticles were deposited on the surface of Fe3O4@TiO2NFs byhydrothermal treatment (Fe3O4@TiO2/CdS). The photocatalytic activity ofFe3O4@TiO2/CdS is7.65times of that of Fe3O4@TiO2, and1.53times of CdS undervisible light irradiation. The utilization of solar spectrum is also enhanced forFe3O4@TiO2/CdS. The photocatalytic activity under simulated solar light is1.11times higher than the one under visible light irradiation. The saturation magnetizationstrength was1.5766emu. g-1. It can be separated and recovered by applying acontactless magnetic field. The photocatalytic activity is stable following thesequence cycles.3. The Plasmon photocatalytic NFs were synthesized by hydrothermallydeposited Ag nanoparitlces on the surface of Fe3O4@TiO2NFs (Fe3O4@TiO2/Ag).The enhanced photocatalytic activity is shown by the increased degradation activity.Under the irradiation of solar light, the activity of Fe3O4@TiO2/Ag is2.18timeshigher than that of Fe3O4@TiO2. The saturation magnetization strength was2.06853emu. g-1. It can be separated and recovered by applying a contactless magnetic field.The photocatalytic activity is stable during the following cycles.4. The Schottky junctions between the Pt nanoparticles and Fe3O4@TiO2wereaccomplished by photochemical reduction of Pt precursor solution (Fe3O4@TiO2/Pt).The enhanced effect of schottky junctions is lower than that of Plasmon effects andheterojunctions. The photocatalytic activity of Fe3O4@TiO2/Pt is only the1.64timesof the one of Fe3O4@TiO2under simulated solar light. The saturation magnetizationstrength was2.06853emu. g-1. It can be separated and recovered by applying acontactless magnetic field.