Abstract
A series of mixed-phases TiO2 is fabricated via a mild hydrothermal process using titanium trichloride as the Ti source and ammonia water for regulating the ratio of anatase, rutile, and brookite. As a result, TiO2 nanocrystals comprised of anatase/brookite, anatase/rutile/brookite and anatase/rutile phases can be obtained. The longest optical edge is observed for triphase TiO2 system among all of the as-prepared samples in UV–vis absorption spectroscopy. However, the results for the photodegradation of levofloxacin indicate that the diphase TiO2 (A61B39) shows higher degradation ratio of levofloxacin instead of triphase TiO2. The reasons for these are attributed to the lowest recombination rate of photoinduced charges, the most negative of flat potential, and the larger specific surface area (SBET = 101 m2/g) for A61B39 sample, which are demonstrated by photoluminescence spectra, Mott-Schottky plots, and N2 adsorption-desorption isotherms. Besides, the intimate interfacial structure of different phase can be observed from high resolution transmission electron microscopy, which contributes to charge transfer. Meanwhile, the photodegradation mechanism of levofloxacin over A61B39 is expounded. This work demonstrates a facile method to regulate the phase ratio of TiO2 and facilitate its application in environmental remediation.
TiO2 nanocrystals with tunable anatase/rutile/brookite phase ratios were synthesized by a hydrothermal reaction of TiCl3 with different concentration of NH3·H2O and photocatalytic degradation of antibiotic levofloxacin was investigated. [Display omitted]
•Mixed-phase TiO2 nanocrystals are obtained via hydrothermal treatment of TiCl3 and NH3·H2O.•The tunable phase ratio of TiO2 is achieved by changing the added concentration of NH3·H2O.•The intimate interfacial structure of different phase contributes to photoinduced charge transfer.•Biphasic TiO2 (A61B39) shows the highest photodegradation activity of levofloxacin.•High photocatalytic properties are results of multiple factors together rather than single factor.