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Hydrothermal synthesis, structural and photocatalytic properties of iron and europium doped TiO2 nanoparticles

Lucian Diamandescu 1Florin Vasiliu 1Doina Tarabasanu-Mihaila 1Marcel Feder 1Mihai Vlaicu 1Cristian M. Teodorescu 1Dan Macovei 1Ionut Marius Enculescu 1Viorica Parvulescu 2Virginia V. Danciu 3Eugen Vasile 4

1. National Institute of Materials Physics (NIMP), Atomistilor 105 bis, Bucharest 077125, Romania
2. Instituite of Physical Chemsitry (ICF), Splaiul Independentei 202, Bucharest 060021, Romania
3. Babes-Bolyai University, Arany Janos 11, Cluj-Napoca 400028, Romania
4. METAV-CD SA, CA Rosetti Nr 31 Sect. 2, Bucharest 70000, Romania

Abstract

Iron and Europium doped TiO2 (titania) nanoparticles powders have been synthesised by a hydrothermal route starting with TiCl4, FeCl3.6H2O and EuCl3.6H2O (Aldrich p.a.) as raw materials.  A stainless steel Teflon lined autoclave was utilized for the hydrothermal runs at 200 °C.  The structure, morphology and optical peculiarities were investigated by means of X-ray diffraction (XRD), transmission electron microscopy (TEM / HRTEM), extended X-ray absorption fine structure (EXAFS), Mössbauer spectroscopy and UV-Vis measurements.  The photocatalytic performance was analysed in the photodegradation of salicylic acid and phenol in water.  Rietveld refinements of XRD patterns reveal that the as resulted samples consist in iron and europium doped TiO2 in the tetragonal-anatase structural shape, with particle dimensions as low as 16 nm.  The doping levels were limited to 1 at. % Fe and Eu, correspondingly.  By means of Mössbauer spectroscopy on both 57Fe and 151Eu isotopes as well as by EXAFS analyses, the presence of Fe3+ and/or Eu3+ ions in the nanosised powders was evidenced.  It was found that both iron and europium ions can substitute titanium ions in the anatase structure.  From UV-Vis reflection spectra, by using the transformed Kubelka-Munk [1] functions, the band gap energy (Eg) for all hydrothermal samples has been determined in comparison with that of Degusa photocatalyst.  A decrease of Eg from 2.9 eV found for Degusa photacatalyst to 2.8 eV for the titania doped with 1 at. % Fe has been evidenced; this behaviour indicates a valuable absorption shift (~ 20 nm) to the visible light region, for the hydrothermally synthesised titania doped sample.  The photocatalytic properties in correlation with the structural and optical peculiarities of the hydrothermal samples are discussed.

1. W. N. Delgass, “Spectroscopy in Heterogeneous Catalysis”, Academic Press, New York, 1979.

 

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Presentation: Poster at E-MRS Fall Meeting 2007, Symposium A, by Lucian Diamandescu
See On-line Journal of E-MRS Fall Meeting 2007

Submitted: 2007-05-02 10:55
Revised:   2009-06-07 00:44