Vendula Houšková

Photocatalytic Activity of Boron-Modified Titania under UV and Visible-Light Illumination

Nanosized boron(III) oxide-doped titania was prepared by homogeneous hydrolysis of titanium oxo-sulfate with urea in aqueous solutions in the presence of amorphous boron. The prepared samples were annealing at 700 degrees C. The structure of as-prepared samples was characterized by X-ray powder diffraction (XRD) and selected area electron diffraction (SAED) and surface area (BET) and porosity determination (BJH). The morphology and microstructure characteristics were obtained by scanning electron microscopy (SEM) and high-resolution electron microscopy (HRTEM). The method of UV/vis diffuse reflectance spectroscopy was employed to estimate band gap energies of the boron-doped titania. The photoactivity of the prepared samples was assessed by the photocatalytic decomposition of Orange II dye in an aqueous slurry during irradiation at 365 and 400 nm wavelength. The prepared titania samples doped with boron(III) oxide showed better photocatalytic activity in comparison with the reference TiO(2) sample. These photocatalysts showed better photocatalytic performance under visible-light irradiation.

Photocatalytic degradation of acetone and butane on mesoporous titania layers

Mesoporous titania was prepared by homogeneous hydrolysis of titanium oxo-sulfate with urea in aqueous solutions in the presence of the cationic and anionic surfactants, cetyl trimethyl ammonium bromide (CTAB) and sodium dodecyl benzene sulfonate (SDBS), respectively. Following annealing at 600 °C the structure of prepared samples was determined with X-ray powder diffraction (XRD) and selected area electron diffraction (SAED). The morphology and microstructure characteristics were also obtained by scanning electron microscopy (SEM) and high resolution electron microscopy (HRTEM). Surface area (BET) and porosity were also determined. From the mesoporous titania samples, a 300 μm thin layer on glass desk 10 × 15 cm was created. The photocatalytic activity of the prepared layers was assessed from the kinetics of the photocatalytic degradation of butane and acetone in the gas phase.

Niobium and tantalum doped titania particles

Niobium and tantalum doped anatase were prepared by thermal hydrolysis of peroxotitanium complex aqueous solutions containing of niobium or tantalum peroxo-complexes at 100 °C for 3 days. Niobium-doping increased the unit cell constants of anatase and changed the morphology of TiO 2 from spindle-like to rectangular or square cross section. Nb and Ta doping in the TiO 2 nanostructure increases the anatase to rutile transformation temperature to >1000 °C. In the visible region, the photocatalytic activity is directly proportional to the concentration and increases with increasing of Nb concentration. The niobium addition enhances the photocatalytic activity of titania in the visible light region.

Photocatalytic properties of Ru-doped titania prepared by homogeneous hydrolysis

Nanocrystalline titania particles doped with ruthenium oxide have been prepared by the homogenous hydrolysis of TiOSO4 in aqueous solutions in the presence of urea. The synthesized particles were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), High Resolution Transmission Electron Microscopy (HRTEM), Selected Area Electron Diffraction (SAED) and Nitrogen adsorption-desorption was used for surface area (BET) and porosity determination (BJH). The photocatalytic activity of the Ru-doped titania samples were determined by photocatalytic decomposition of Orange II dye in an aqueous slurry during irradiation at 365 nm and 400 nm wavelengths.