Search results for "element"
showing 10 items of 13601 documents
Pulsed laser growth and characterization of thin films on titanium substrates
2007
Abstract Colored layers were obtained by laser surface treatment of Ti substrates with a pulsed Nd:YAG Q-switched laser. The changes in the morphology, structure and chemical composition of the layers were studied by SEM, EDS, XPS, SIMS and Raman spectroscopy as a function of the laser fluence in the 4–60 J cm −2 . For laser fluences lower than 25 J cm −2 , the layers are colorless or yellow. Their surface is smooth, but they display cracks which increase when the fluence increases. The O/Ti ratio, determined by XPS analysis, varies from 0.7 (colorless layers) to 1.3 (yellow layer). Moreover, XPS spectra evidence non-negligible amounts of nitrogen and carbon in these layers. Raman spectra s…
A comparative study of the photocatalytic activities of iron-titanium (IV) oxide photocatalysts prepared by various methods; spray pyrolysis, impregn…
1995
Abstract A series of iron/titanium oxide photocatalysts of varying Fe 3+ content have beenprepared by a number of different methods and subjected to controlled thermal treatment. Specimens have been characterised in terms of their crystalline structure and morphology, and indicate solid solutions containing both the anatase and rutile phases of TiO 2 , together with the formation of pseudo-brookite in some specimens. Intrinsic photo-activity measurements have been performed using a standard liquid-phase photocatalytic reaction. Results indicate that the photocatalytic activity of the specimens differs according to the method of preparation, and that all solids containing iron (III) species …
Preparation and characterisation of TiO2 (anatase) supported on TiO2 (rutile) catalysts employed for 4-nitrophenol photodegradation in aqueous medium…
1999
Abstract In this paper the preparation of two sets of polycrystalline photocatalysts prepared by supporting TiO2 (anatase) on TiO2 (rutile) or Al2O3 is reported. The powders were prepared by a wet impregnation method using titanium(IV) isopropylate. The impregnation was followed by thermal treatment and this procedure was repeated several times in order to obtain samples with progressively increasing amounts of TiO2 (anatase). The photocatalytic activity of all of the specimens was tested by carrying out the 4-nitrophenol photodegradation, used as a “probe” reaction, in aqueous medium and in different kinds of batch photoreactors. The solids were characterised by X-ray diffraction (XRD), sp…
Cr- and Sb-containing TiO 2 inorganic orange nano-pigments prepared by a relative long hydrocarbon chain polyol
2016
Abstract We report the preparation of a series of orange Cr- and Sb-containing TiO 2 nano-pigments by the polyol via using triethylenglycol (TEG). Poorly crystallized anatase nanopowders with nominal stoichiometric compositions Cr x Sb x Ti 1−2x O 2 , with 0 ≤ x ≤ 0.2, were obtained by heating at 180 °C a solution of antimony acetate, chromium acetylacetone and titanium butoxide in TEG. The transition temperature of the chromium- and antimonium-containing anatase nanoparticles into the rutile crystalline form occurred over the range of temperature between 500 and 650 °C, depending on the dopant amount. After annealing at 800 °C for short time the series of samples displaying the rutile stru…
Combined Adsorption/Photocatalytic dye removal by copper-titania-fly ash composite
2020
Abstract Achieving both photocatalytic efficiency and adsorption capacity is essential to produce a highly efficient photocatalyst. This study fabricated a new photocatalyst by combining copper (Cu) doped titanium dioxide (TiO2) with fly ash (FA). The photocatalysts were synthesized using mild acid (acid-FA/Cu/TiO2), base (base-FA/Cu/TiO2), and deionized water (rFA/Cu/TiO2) activated FA. EDX confirmed the inclusion of Cu in both Cu/TiO2 and FA/Cu/TiO2 composites. XRD analysis indicated the presence of the anatase form of TiO2 after Cu doping and incorporation into modified FA. All three FA/Cu/TiO2 composites demonstrated high absorption (UV and visible region) compared to their TiO2 and Cu/…
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 …
Nanostructured Pt–TiO2 composite thin films obtained by direct liquid injection metal organic chemical vapor deposition: Control of chemical state by…
2015
Abstract Nanostructured Pt–TiO 2 composite thin films were synthesized by direct liquid injection metal organic chemical vapor deposition process, using trimethyl(methylcyclopentadienyl)platinum and titanium isopropoxide as precursors. Surface and cross-sectional morphologies obtained by scanning electron microscopy and transmission electron microscopy evidenced the uniform distribution of platinum nanoparticles in the TiO 2 matrix. At higher Pt content, the X-ray diffraction analysis showed that the face-centered cubic phase of platinum appeared together with an anatase TiO 2 structure. In addition, as far as the platinum chemical state is concerned, the co-deposition of TiO 2 and Pt allow…
A study of the interaction between iron(III)oxide and titanium(IV)oxide at elevated temperatures
1991
Abstract The bulk interaction between iron(III) oxide and titanium(IV) oxide occurs at temperatures in excess of 773 K. Initially iron(III) ions dissolve in the titanium(IV) oxide structure to produce a substitutional solid solution. Magnetic evidence suggests that there is a solubility limit of iron(III) ions in the region of ca. 3 atom %. Significantly the phase transition from the anatase phase to the rutile phase is observed to occur approximately 200 K lower in the presence of iron than when it is absent. Further reaction between iron(III) oxide and the saturated solution in the rutile phase occurs at 1073 K with the formation of pseudo-brookite. Under high vacuum conditions the therma…
Preparation characterization and photocatalytic activity of polycrystalline ZnO/TiO2 systems. 2. Surface, bulk characterization, and 4-nitrophenol ph…
2001
Electron spin resonance spectroscopy (ESR), Fourier transform infrared spectroscopy (FTIR), and monitoring of pyridine (py) and boric acid trimethyl ester (BATE) adsorption for determining surface acidity and basicity, respectively, were used to carry out further characterization of mixed ZnO/TiO2 polycrystalline solids prepared by different methods. Moreover, the powders were tested in a batch photoreactor for a probe reaction, i.e., 4-nitrophenol photodegradation in aqueous medium. ESR results indicated the presence of signals attributable to Zn+ species in ZnO/TiO2 (anatase) solids, while in ZnO/TiO2 (rutile) samples the presence of zinc induced only the formation of signals probably due…
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