New insights into polymer mediated formation of anatase mesocrystals

The reaction between (NH4)2TiF6 and H3BO3 in the presence of varying quantities of PEG-6000 was used to form NH4TiOF3 mesocrystals (MCs). The amount of PEG-6000, employed as a template, is crucial to the formation of defect free, non-agglomerated NH4TiOF3 MCs; high concentrations lead to MC agglomeration, lower ones result in centralized defects. This polymer-mediated formation process may be understood using an analogy with known polymerization reactions. The oxofluorotitanate MCs readily undergo a thermal topotactic transformation to give anatase MCs with photocatalytic activity. The TiO2 MCs are porous, with highly orientated lamellar crystallites that form part of the larger mesocrystal structure

Nanowhiskers of K2Ti6O13 as a promoter of photocatalysis in anatase mesocrystals

Here we describe the development of a new mesocrytalline anatase-based photocatalyst with an activity nearly double that of the commercial Evonik Aeroxide® TiO2 P25 catalyst. An extensive characterization of this new catalytic material with XRD, TEM, SAED, EELS, SEM, RAMAN and XPS shows that its activity is promoted by its hybrid structure comprising mesocrystalline anatase and K2Ti6O13 whiskers formed within the TiO2 mesocrystals. This new and unexpected component is formed in situ within the TiO2 mesocrystalline framework at a surprisingly low temperature of 500 °C as a result of potassium diffusion from polymer-matrix phase. The growth of whiskers occurs at the 001 TiO2 planes of mesocrystals and their sizes attain 60 nm in a section and a few μm in length

One step microwave-assisted synthesis of fluorinated titania photocatalyst

Microwave-assisted high temperature hydrolysis of titanium oxysulfate, in the presence of ammonium fluoride, allows synthesizing nanocrystalline titanium dioxide photocatalysts possessing photocatalytic activity as high as the commercial photocatalyst Evonik Aeroxide® TiO2 P 25. Dye-sensitized reactions play an important role in organic dye discoloration in the presence of fluorinated titania

One step microwave-assisted synthesis of fluorinated titania photocatalyst

Microwave-assisted high temperature hydrolysis of titanium oxysulfate, in the presence of ammonium fluoride, allows synthesizing nanocrystalline titanium dioxide photocatalysts possessing photocatalytic activity as high as the commercial photocatalyst Evonik Aeroxide® TiO2 P 25. Dye-sensitized reactions play an important role in organic dye discoloration in the presence of fluorinated titania

Hydrothermal synthesis of nanocrystalline titanium dioxide for use a photoanode of DSSCs

Nanocrystalline TiO2 powder was synthesized using microwave-assisted hydrothermal treatment of titanium oxysulfate in the presence of NH4F. X-ray powder diffraction analysis and Raman spectroscopy were used to determine phase composition and particle size of obtained titanium dioxide. The studies using methods of TEM and EDX spectroscopy have shown that synthesized TiO2 powder is a promising functional material for fabrication of photoanode of dye-sensitized solar cells (DSSCs)

Hydrothermal synthesis of nanocrystalline titanium dioxide for use a photoanode of DSSCs

Nanocrystalline TiO2 powder was synthesized using microwave-assisted hydrothermal treatment of titanium oxysulfate in the presence of NH4F. X-ray powder diffraction analysis and Raman spectroscopy were used to determine phase composition and particle size of obtained titanium dioxide. The studies using methods of TEM and EDX spectroscopy have shown that synthesized TiO2 powder is a promising functional material for fabrication of photoanode of dye-sensitized solar cells (DSSCs)

Enhanced interfacial Dzyaloshinskii-Moriya interaction and isolated skyrmions in the inversion-symmetry-broken Ru/Co/W/Ru films

An enhancement of the spin-orbit effects arising on an interface between a ferromagnet (FM) and a heavy metal (HM) is possible through the strong breaking of the structural inversion symmetry in the layered films. Here, we show that an introduction of an ultrathin W interlayer between Co and Ru in Ru/Co/Ru films enables to preserve perpendicular magnetic anisotropy (PMA) and simultaneously induce a large interfacial Dzyaloshinskii-Moriya interaction (iDMI). The study of the spin-wave propagation in the Damon-Eshbach geometry by Brillouin light scattering spectroscopy reveals the drastic increase in the iDMI value with the increase in W thickness (tW). The maximum iDMI of −3.1 erg/cm2 is observed for tW = 0.24 nm, which is 10 times larger than for the quasi-symmetrical Ru/Co/Ru films. We demonstrate the evidence of the spontaneous field-driven nucleation of isolated skyrmions supported by micromagnetic simulations. Magnetic force microscopy measurements reveal the existence of sub-100-nm skyrmions in the zero magnetic field. The ability to simultaneously control the strength of PMA and iDMI in quasi-symmetrical HM/FM/HM trilayer systems through the interface engineered inversion asymmetry at the nanoscale excites new fundamental and practical interest in ultrathin ferromagnets, which are a potential host for stable magnetic skyrmions

Photocatalytically active fluorinated nano-titania synthesized by microwave-assisted hydrothermal treatment

Nanocrystalline fluorinated titania has been prepared using microwave-assisted hydrothermal crystallization of hydrous titania in a NH4F aqueous solution. Thus, obtained TiO2 has exhibited excellent photocatalytic activity in the reaction of crystal violet dye photodegradation – up to twofold higher than the photocatalytic activity of the commercial Evonik Aeroxide® TiO2 P25 photocatalyst. Hydrothermal treatment temperature and the concentration of ammonium fluoride in the reaction mixture have been shown to be key parameters, providing the most significant effect on the microstructure and photocatalytic activity of titania

Photocatalytically active fluorinated nano-titania synthesized by microwave-assisted hydrothermal treatment

Nanocrystalline fluorinated titania has been prepared using microwave-assisted hydrothermal crystallization of hydrous titania in a NH4F aqueous solution. Thus, obtained TiO2 has exhibited excellent photocatalytic activity in the reaction of crystal violet dye photodegradation – up to twofold higher than the photocatalytic activity of the commercial Evonik Aeroxide® TiO2 P25 photocatalyst. Hydrothermal treatment temperature and the concentration of ammonium fluoride in the reaction mixture have been shown to be key parameters, providing the most significant effect on the microstructure and photocatalytic activity of titania