F-doped TiO2 Research Articles

Preparation, Characterization and Photocatalytic Activities of F-doped TiO2 Nanotubes

F-doped TiO2 nanotubes were prepared by impregnation method. The prepared catalysts were characterized by XRD, TEM, and XPS. The photocatalytic activity of F-doped TiO2 nanotubes was evaluated through the photodegradation of aqueous methyl orange. The experiments demonstrated that the F-doped TiO2 nanotubes calcined at 300 °C possessed the best photocatalytic activity. Compared with pure TiO2 nanotubes, the doping with F− significantly enhanced the photocatalytic efficiency. The high photocatalytic activity was ascribed to several beneficial effects produced by F-doping: creation of oxygen vacancies, presence of Ti3+, and so on.

Synthesis of Self-Organized Polycrystalline F-doped TiO2 Hollow Microspheres and Their Photocatalytic Activity under Visible Light

A wet-chemistry method was used to dope F- ions into crystalline TiO2 by hydrothermal treatment of TiF4 in an HCl solution. Field-emission electron microscope and transmission electron microscope images showed that the products exhibited a flowerlike morphology with a hollow interior. X-ray photoelectron spectroscope data demonstrated the doping of F in the lattice of crystalline TiO2. The flowerlike F-doped TiO2 hollow microspheres synthesized at 180 °C showed the highest photocatalytic activity for the degradation of methylene blue under visible light irradiation. Ostwald ripening is the main reason responsible for the formation of the hollow interior of the F-doped TiO2 micropheres, and the HF species generated from the hydrothermal reaction is believed to accelerate the formation of the TiO2 hollow spheres.

Synthesis of F-Doped Flower-like TiO2 Nanostructures with High Photoelectrochemical Activity

We report on a novel and facile approach for the direct growth of F-doped flower-like TiO(2) nanostructures on the surface of Ti in HF solutions under low-temperature hydrothermal conditions. The influence of the experimental parameters such as temperature, reaction duration, and the HF concentration on the morphology and photoelectrocatalytic activity of the formed F-doped flower-like TiO(2) nanostructures was systematically studied. The presence of HF and the reaction time play an important role in the formation of the F-doped flower-like TiO(2) nanostructures. The synthesized novel F-doped TiO(2) flower-like nanomaterials possess good crystallinity and exhibit high photoelectrochemical activity for water-splitting and photodegradation of organic pollutants compared with P-25, which is currently considered to be one of the best commercial TiO(2) photocatalysts. The approach described in this study provides a simple and novel method to synthesize F-doped TiO(2) nanostructured materials that are ready for practical applications such as the photodegradation of wastewater.

Low-temperature preparation of F-doped TiO 2 film and its photocatalytic activity under solar light

A novel and simple method for preparing F-doped anatase TiO 2 (defined as FTO) film with high photocatalytic activity was developed using titanium- n-butoxide and NH 4F as TiO 2 and fluorine precursors under mild condition, i.e. low temperature (lower than 373 K) and ambient pressure. The prepared samples were characterized by XRD, SEM, X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectrum (DRS), photoluminescence spectrum (PL) and TG–DSC analysis. The photocatalytic activity was evaluated by decomposing X-3B under artificial solar light. The results showed that the crystallinity of TiO 2 was improved by F-doping. F − ions can prevent the grain growth, and the transformation of anatase to rutile phase was also inhibited. The doped fluorine atoms existed in two chemical forms, and the ones incorporated into TiO 2 lattice might take a positive role in photocatalysis. Compared with surface fluorination samples, FTO film exhibited better photocatalytic activity. The high photocatalytic activity of FTO may due to extrinsic absorption through the creation of oxygen vacancies rather than the excitation of the intrinsic absorption band of bulk TiO 2. Furthermore, the FTO can be recycled with little photocatalytic activity depression. Without any further treatment besides rinsing, after 6 recycle utilization, the photocatalytic activity of FTO film was still higher than 79%.

Direct growth of F-doped TiO 2 particulate thin films with high photocatalytic activity for environmental applications

Here we report on a novel and facile approach to directly grow F-doped TiO 2 particulate thin films with superb visible light photoelectrical response and high photocatalytic efficiency by oxidizing titanium plates in the presence of H 2O vapor assisted with NaF at relatively low temperatures. The effects of the oxidation temperature and the amount of the NaF coated on the titanium plates on the morphology and the photocatalytic properties of the formed F-doped TiO 2 particulate thin films have been investigated. The formed F-doped TiO 2 particulate thin films show a significant increase in the photocurrent of photoinduced splitting of water into hydrogen and oxygen compared with that of commercial P-25 TiO 2, under irradiation of either UV or visible light. In addition, the photocatalytic activity of the formed F-doped TiO 2 particulate thin films out perform the commercial P-25 TiO 2 for the photodegradation of 4-nitrophenol under UV and visible light irradiation. The approach described in this study can be easily commercialized to fabricate F-doped TiO 2 particulate thin films on a large-scale for very promising environmental applications in the photodegradation of organic pollutants and photoinduced splitting of water into hydrogen, a green energy source.

Synthesis of hierarchical nanoporous F-doped TiO2 spheres with visible light photocatalytic activity

Hierarchical porous F-doped TiO2 microspheres exhibiting high visible light photocatalytic activity have been fabricated by a one-step low-temperature hydrothermal approach without using any templates.

Visible-light-driven photocatalysis on fluorine-doped TiO 2 powders by the creation of surface oxygen vacancies

F-doped TiO 2 (FT) powders were prepared by spray pyrolysis from an aqueous solution of H 2TiF 6. These FT powders demonstrated very high visible-light (Vis) photocatalytic activities for decompositions of both acetaldehyde and trichloroethylene, although their UV–Vis spectra indicated that F-doping had less effect on the optical absorption property of bulk TiO 2. However, photoluminescence (PL) spectra revealed that two kinds of oxygen vacancies ( F and F + centers) were formed by F-doping. The appearance of Vis photocatalytic activity for FT powders was ascribed to the creation of these oxygen vacancies.

Fluorine-doped TiO 2 powders prepared by spray pyrolysis and their improved photocatalytic activity for decomposition of gas-phase acetaldehyde

F-doped TiO 2 (FTO) powders were synthesized by spray pyrolysis (SP) from an aqueous solution of H 2TiF 6. The resulting FTO powders possessed spherical particles with a rough surface morphology and a strong surface acidity. The fluorine concentrations in the FTO powders calculated from XPS spectra significantly depended on SP temperature and ranged from 2.76 to 9.40 at.%. The FTO powder prepared at SP temperature of 1173 K demonstrated the highest photocatalytic activity for the decomposition of gas-phase acetaldehyde under both ultraviolet (UV) and visible light (vis) irradiations, and it was higher than that of commercial P 25. This high photocatalytic activity was ascribed to several beneficial effects produced by F-doping: enhancement of surface acidity, creation of oxygen vacancies, and increase of active sites. It was interesting to point out that the vis photocatalytic activity of FTO powders was achieved by the creation of surface oxygen vacancies rather than the improvement of optical absorption property of bulk TiO 2 in vis region.

High photocatalytic activity of F-doped TiO2 film on glass

The photoreactivity of sol-gel (SG)-TiO2 films was enhanced significantly with addition of a small amount of trifluoroacetic acid (TFA) into the starting solution. The promoting effect was confirmed in two separate experiments of the methylsiloxane monolayer oxidation and the photocurrent measurements. The results of film characterization indicated that the absorption coefficient for ultraviolet light (λ < 360 nm) increases due to film densification and the crystallinity is improved upon F doping. The improvement in the photoreactivity was ultimately attributed to the increase in the rate at which the photogenerated charge carriers reach the surface in the photostationary state.