Francesca Visentin

Fe2O3-TiO2 systems grown by MOCVD: an XPS study

The present work was devoted to the X-ray photoelectron spectroscopy (XPS) investigation of the principal core levels of a Fe2O3-TiO2 system. The sample was synthesized on a glass substrate at 430 °C in N2/O2 atmospheres by low-pressure metal organic chemical vapor deposition (MOCVD) co-evaporating the precursors titanium(IV)isopropoxide [Ti(OiPr)4] and bis-(methylcyclopentadienyl)Fe(II) [Fe(MeCp)2] through independent sources. Beside the wide scan spectrum, detailed spectra for O 1s, Fe 2p and Ti 2p regions and related data are presented and discussed. XPS analysis revealed the presence of iron(III) and titanium(IV) oxides as the main phases, with a possible Fe2O3 segregation on the specimen surface.

Effective and Low-Cost Synthesis of Sulphur-Modified TiO 2 Nanopowder with Improved Photocatalytic Performances in Water Treatment Applications

In the present paper, sulphur-modified titanium dioxide (S-TiO2) is prepared as nanopowder in mixed rutile-anatase phase by an unprecedented simple, reproducible and cheap synthetic procedure, directly employing elemental sulphur powder as sulphur source. TiO2 and several reference TiO2 samples obtained in pure rutile or anatase phase were also prepared with nanometric size and compared to S-TiO2 as well as Degussa P25. The prepared samples and the reference benchmark were characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FT-IR), BET specific surface area and X-ray photoelectron spectroscopy (XPS) techniques, while their photoactivity was determined with respect to methyl red degradation as typical probe reaction. The results from the characterisation and photocatalytic measurements were discussed and inter-correlated, thus providing a complete and consistent analysis of the samples performances. The prepared sulphur-modified titanium dioxide appeared as a very efficient and long-lasting photocatalyst with respect to the unmodified TiO2 and to the benchmark Degussa P25 (S-TiO2 appears to be two times faster than P25) for the methyl red removal under UV lighting, also in repeated cycles.