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Dive into the research topics where Andri Vital is active.

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Featured researches published by Andri Vital.


International Journal of Photoenergy | 2005

One-step flame synthesis of SnO2 / TiO2 composite nanoparticles for photocatalytic applications

Kranthi K. Akurati; Andri Vital; Roland Hany; Bastian Bommer; Thomas Graule; Markus Winterer

SnO2 / TiO2 composite nanoparticles have been synthesized in a single-step by feeding evaporated precursor mixtures into an atmospheric pressure diffusion flame. Particles with controlled Ti: Sn ratios were produced at various flow rates of oxygen, and the resulting powders were characterized by BET surface area analysis, XRD, TEM, EDAX and UV-Vis spectroscopy. For the lowest concentration (3.4 mol %) of SnO2 employed in this study anatase phase of TiO2 is stabilized, while segregation of SnO2 is seen at medium (6.9 to 12.4 mol %) and high concentrations (20.3 mol %). Though the equilibrium phase diagram predicts complete solubility of one oxide in another at all compositions, segregation of SnO2 phase is observed which is explained by the usage of diffusion flame in the present study. The particle formation mechanism of SnO2 / TiO2 composites is proposed basing on the single component aerosol formation. Photocatalytic activity of the composite particles is tested for the degradation of methylene blue and is compared with pure TiO2 synthesized under similar conditions. Improved photocatalytic activity of the composite particles is attributed to the stabilized anatase phase and better charge separation due to the coupling of TiO2 and SnO2 within the composite nanoparticles.


Journal of Advanced Oxidation Technologies | 2008

Photocatalytic Activity of W-Doped TiO2 Nanopowders

Katarzyna A. Michalow; Andri Vital; Andre Heel; Thomas Graule; Felix A. Reifler; Axel Ritter; K. Zakrzewska; M. Rekas

Abstract Polycrystalline tungsten-doped titanium dioxide nanopowders within a dopant concentration of 0-1 at.% were prepared by a one-step flame spray synthesis (FSS). Mixtures of titanium tetra-isopropoxide dissolved in ethanol and tungsten hexacarbonyl solubilized in tetrahydrofuran were used as precursors. The specific surface area (SSA) of the powders was between 40 and 130 m2/g depending on the process parameters, namely the flame combustion stoichiometry and their chemical composition. Irrespective of their composition the powders consisted of spherical particles, as visible by transmission electron microscopy (TEM). They are highly crystallized with anatase as the predominant phase, according to X-ray diffraction (XRD). The band gap energy was determined by spectrophotometric measurement and was between 3.29 eV and 3.34 eV. The photocatalytic performance of the powders was studied by the degradation of methylene blue (MB) and methyl orange (MO) in aqueous suspensions under UV-A (365 nm) as well as visible (400-500 nm) irradiation. The catalytic activity was determined as a function of the tungsten concentration, the specific surface area and the flame combustion stoichiometry. It was found that the TiO2-0.7 at %W particles with high SSA have the highest photoactivity for degradation of MB and MO. This can be explained by the incorporation of the tungsten into the TiO2 crystal lattice as well as modification surface properties.


Archive | 2003

Synthesis of Spherical, Non-Aggregated Silica Nanoparticles

Andri Vital; U. Klotz; T. Graule; R. Mueller; H. K. Kammler; Sotiris E. Pratsinis

Commercially available SiO2 nanopowders synthesised by flame aerosol processes consist to a major part of large aggregates, formed by collision and sintering of primary particles during the process. These aggregates impair the physical and chemical benefits, which could be achieved from the properties of the primary, non-aggregated nanoparticles.


Applied Catalysis B-environmental | 2008

Flame-made WO3/TiO2 nanoparticles: Relation between surface acidity, structure and photocatalytic activity

Kranthi K. Akurati; Andri Vital; Jean-Philippe Dellemann; Katarzyna A. Michalow; Thomas Graule; Davide Ferri; Alfons Baiker


Composites Part A-applied Science and Manufacturing | 2005

Innovative, scratch proof nanocomposites for clear coatings

Elisabeth Barna; Bastian Bommer; Jürg Kürsteiner; Andri Vital; Oliver von Trzebiatowski; Walter Koch; Bruno Schmid; Thomas Graule


Powder Technology | 2004

Non-agglomerated dry silica nanoparticles

Roger Mueller; Hendrik K. Kammler; Sotiris E. Pratsinis; Andri Vital; Gregory Beaucage; Peter Burtscher


Solid State Sciences | 2007

Flame synthesis of TiO2 nanoparticles with high photocatalytic activity

Kranthi K. Akurati; Andri Vital; Giuseppino Fortunato; Roland Hany; Frank Nueesch; Thomas Graule


Polymer Degradation and Stability | 2007

Thermal stability of poly(methyl methacrylate)/silica nano-and microcomposites as investigated by dynamic-mechanical experiments

Nikolaos Katsikis; Franz Zahradnik; Anne Helmschrott; Helmut Münstedt; Andri Vital


Journal of Physical Chemistry C | 2010

Nitrogen Doping of TiO2 Photocatalyst Forms a Second eg State in the Oxygen 1s NEXAFS Pre-edge

Artur Braun; Kranthi K. Akurati; Giuseppino Fortunato; Felix A. Reifler; Axel Ritter; Ashley S. Harvey; Andri Vital; Thomas Graule


Powder Technology | 2006

Synthesis of non-aggregated titania nanoparticles in atmospheric pressure diffusion flames

Kranthi K. Akurati; Andri Vital; Ulrich E. Klotz; Bastian Bommer; Thomas Graule; Markus Winterer

Collaboration


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Thomas Graule

Freiberg University of Mining and Technology

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Kranthi K. Akurati

Swiss Federal Laboratories for Materials Science and Technology

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Bastian Bommer

Swiss Federal Laboratories for Materials Science and Technology

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Giuseppino Fortunato

Swiss Federal Laboratories for Materials Science and Technology

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Andre Heel

Swiss Federal Laboratories for Materials Science and Technology

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Katarzyna A. Michalow

Swiss Federal Laboratories for Materials Science and Technology

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R. Dittmann

Swiss Federal Laboratories for Materials Science and Technology

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Axel Ritter

Swiss Federal Laboratories for Materials Science and Technology

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Felix A. Reifler

Swiss Federal Laboratories for Materials Science and Technology

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Roland Hany

Swiss Federal Laboratories for Materials Science and Technology

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