Abstract
The crystal phases and surface states of TiO2 can intrinsically determine its performance in the applications of photocatalysis. Here, we prepared TiO2 nanofibers with different crystal phase contents by electrospinning followed via calcination at different temperatures. The TiO2 nanofibers were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectrometry, transmission electron microscopy (TEM), and photocatalytic performance testing. The results showed that the phases of TiO2 nanofibers were layered, that surface crystal phase transition rate was faster than that of internal layers contributed the difference in the ratio of anatase and rutile in the outer and inner layer of TiO2 nanofibers. The TiO2 nanofibers obtained at 575 °C had the best photocatalytic activity, taking only 25 min to degrade Rhodamine B. At 575 °C, the rutile content of the sample surface was about 80 wt.%, while the internal rutile content was only about 40 wt.%. Subsequently, we prepared two different structures of anatase–rutile core-shell TiO2 nanofibers. The core-shell structure can be clearly seen by TEM characterization. The photocatalytic activity of two kinds of core-shell TiO2 nanofibers was tested. The results showed that the photocatalytic activity was close to that of the pure phase TiO2 nanofibers, which corresponded with the surface phase. This further proves that the photocatalytic activity of the material is mainly affected by its surface structure.
Highlights
With the acceleration of industrial modernization, people have discharged large amounts of production waste water into the environment they live in, which contain many toxic pollutants such as pesticides and industrial dyes
It is expected that if the proportion of anatase/rutile in the inner and outer layers of TiO2 nanofibers could be tunable, the interaction between rutile and anatase phases can exert a variable influence on the surface structure and properties of TiO2 nanofibers, which would be important for designing superior photocatalysts and for further understanding of the photocatalysis processes
We studied the photocatalytic properties of TiO2 nanofibers where the inner and outer layers contained different anatase/rutile ratios and discussed the relationship between crystal structure and its photocatalytic performance in detail
Summary
With the acceleration of industrial modernization, people have discharged large amounts of production waste water into the environment they live in, which contain many toxic pollutants such as pesticides and industrial dyes. Titanium dioxide (TiO2) has been widely investigated in the field of photocatalysis because of its superior photocatalytic activity, chemical stability, low cost, and nontoxicity [8,9,10,11] It is well-known that the crystal phase of TiO2 plays an important role in photocatalysis. It is expected that if the proportion of anatase/rutile in the inner and outer layers of TiO2 nanofibers could be tunable, the interaction between rutile and anatase phases can exert a variable influence on the surface structure and properties of TiO2 nanofibers, which would be important for designing superior photocatalysts and for further understanding of the photocatalysis processes. We studied the photocatalytic properties of TiO2 nanofibers where the inner and outer layers contained different anatase/rutile ratios and discussed the relationship between crystal structure and its photocatalytic performance in detail. In order to prove that the surface morphology of TiO2 nanofibers plays a decisive role in its photocatalytic activity, the core-shell TiO2 nanofibers with different crystal structures were prepared by the hydrolysis treatment of TiO2 nanofibers, and the photocatalytic properties of the core-shell nanofibers were studied
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