Search results for "Tecnologie"
showing 10 items of 1379 documents
TiO2 photocatalysts prepared by thermohydrolysis of TiCl4 in aqueous solutions
2010
Abstract Nanostructured TiO 2 photocatalysts were synthesized by thermohydrolysis of TiCl 4 at 100 °C in various aqueous solutions. Anatase or rutile, binary mixtures of anatase and rutile or anatase and brookite, and ternary mixtures of anatase, brookite and rutile were obtained depending on the hydrolysis solution. The most efficient catalysts consisted of ternary mixtures of the three polymorphic TiO 2 phases.
Nature of Interactions at the Interface of Two Water-Saturated Commercial TiO2 Polymorphs
2013
Two commercial TiO2 samples, a 100% anatase and a 100% rutile, were used for the fast field cycling NMR experiments. The results showed a different behavior between the different samples. In particular, water molecules were unbonded to the solid surface for the rutile sample, whereas they appeared to chemically interact with the surface through H-bond formation with the anatase sample. The above findings accord with the generally lower activity of rutile with respect to anatase reported in literature for photocatalytic oxidation reactions in water. The difficulty of water to interact with rutile surface, indeed, could hinder the formation of OH radicals, which are the most important oxidant…
Effect of titanium dioxide crystalline structure on the photocatalytic production of hydrogen
2011
The effect of the crystalline phase of TiO 2 (anatase, rutile and brookite) on its photocatalytic activity in hydrogen production from methanol-water vapours has been investigated by testing a series of both home-made and commercial TiO 2 photocatalysts, either bare or surface-modified by deposition of a fixed amount, i.e. 1 wt%, of platinum as co-catalyst. For all of the TiO 2 samples the rate of hydrogen production increased by one order of magnitude upon Pt deposition, because of the ability of Pt to enhance the separation of photoproduced electron-hole pairs. Under irradiation in the 350-450 nm wavelength range, brookite and anatase showed similar photoactivities, both superior to that …
Step-by-Step Growth of HKUST-1 on Functionalized TiO2 Surface: An Efficient Material for CO2 Capture and Solar Photoreduction
2018
The present study reports on a simple preparation strategy of a hybrid catalyst, TiO2/HKUST-1, containing TiO2 anatase nanoparticles (NPs) with tailored morphology and photocatalytic activity coupled with a porous metal-organic framework (MOF), namely HKUST-1, as an advanced material for the CO2 photocatalytic reduction. In detail, TiO2/HKUST-1 catalyst was prepared via an easy slow-diffusion method combined with a step-by-step self-assembly at room temperature. The growth of crystalline HKUST-1 onto titania surface was achieved by functionalizing TiO2 nanocrystals, with phosphoesanoic acid (PHA), namely TiO2-PHA, which provides an intimate contact between MOF and TiO2. The presence of a cr…
Preparation and photoactivity of nanostructured anatase, rutile and brookite TiO2 thin films
2006
Photoactive films consisting of pure anatase, brookite or rutile TiO2 were prepared by dip coating from water dispersions obtained by using TiCl4 as the precursor under similar mild experimental conditions
Effect of the addition of different doping agents on visible light activity of porous TiO2 photocatalysts
2018
Abstract The influence of the addition of different doping agents (N, W and Hf) on the macroporous TiO2 photoactivity toward the Rhodamine B degradation and ethanol photo-oxidation was evaluated. The samples were characterized by XRD, XPS, SEM, TEM, N2 adsorption-desorption, UV–vis Diffuse Reflectance and Photoluminescence spectroscopies to study also the changes in the physico-chemical properties due to the presence of dopants. The photonic effect and the high ordered porous structure of the macroporous TiO2 that lead to increase the path length of the light, were the key factors that allow to enhance the catalytic activity towards the dye and VOC degradation under visible and solar light …
Reduced grey brookite for noble metal free photocatalytic H2evolution
2021
Herein we introduce for the first time a reduced “grey” brookite TiO2 photocatalyst, produced by thermal hydrogenation of brookite nanoparticles, that shows a remarkable noble metal free photocatalytic H2 evolution. Its activity is substantially higher than that of other TiO2 polymorphs, i.e. anatase or rutile, comparably sized and activated by hydrogenation under optimized conditions. Along with brookite powders, an oriented brookite single crystal was investigated as a defined surface to confirm the effects of the hydrogenation treatment. By a combination of electron paramagnetic resonance (EPR), electron and X-ray characterization techniques applied to the powders and single crystal, we …
Preparation and photoactivity of samarium loaded anatase, brookite and rutile catalysts
2011
Abstract Pure and samarium loaded anatase, brookite and rutile nanopowders were synthesized by thermohydrolysis of TiCl 4 . The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), specific surface area (SSA) determination, UV–vis diffuse reflectance spectroscopy (DRS), atomic force microscopy (AFM), contact angle (CA) measurements and photoluminescence (PL) spectroscopy. The photocatalytic activity of pure and Sm-loaded TiO 2 polymorphs was investigated by employing the photodegradation of 4-nitrophenol as probe reaction in a liquid-solid system. Loading with Sm resulted in an improvement of the photoreactivity of the three TiO 2 polymorphs. The benefi…
Photocatalytic Selective Oxidation of 5-(Hydroxymethyl)-2-furaldehyde to 2,5-Furandicarbaldehyde in Water by Using Anatase, Rutile, and Brookite TiO2…
2013
5-(Hydroxymethyl)-2-furaldehyde (HMF) was selectively oxidized to 2,5-furandicarbaldehyde (FDC) in; aqueous medium by using home prepared (HP) anatase, rutile, and brookite TiO2 nanoparticles. HP samples were prepared via a sol-gel method by using TiCl4 as the TiO2 precursor. Commercial TiO2 catalysts were also used for, comparison. All samples were characterized by BET specific surface area, XRD, TGA, and SEM, and the reactivity results showed that HP catalysts are predominantly amorphous and give rise to selectivities toward FDC more than twice that of commercial and well crystallized catalysts.
Home-prepared anatase, rutile, and brookite TiO2 for selective photocatalytic oxidation of 4-methoxybenzyl alcohol in water: reactivity and ATR-FTIR …
2009
5th European Meeting on Solar Chemistry and Photocatalysis -- OCT 04-08, 2008 -- Palermo, ITALY