Photocatalytic, spectroscopic and transport properties of lanthanide-doped TiO₂nanocrystals

Abstract

The photocatalytic properties of the anatase form of nanocrystalline TiO 2 doped with lanthanide ions (Eu 3+ , Sm 3+ and Er 3+ ), obtained by a sol-gel preparation method, are studied by means of the degradation of methylene blue. It is observed that the presence of Sm 3+ ion as a dopant significantly improves the photocatalytic activity of anatase TiO 2 with respect to the Eu 3+ or Er 3+ ions.For the understanding of such a catalytic process the charge transport in these systems is studied by an appropriate Monte Carlo simulation which includes phonons, charged impurities and traps. The obtained results evidence the important role of the traps for the transit of the electrons in the systems investigated here. They decrease the diffusion coefficient by about three orders of magnitude with respect to the bulk, from which it is possible to obtain a simple estimate of the reaction rate in agreement with experimental results. All the lanthanide-doped samples show a strong luminescence in the visible region. The emission bands are affected by a notable inhomogeneous broadening, indicating a high disorder of the crystalline environment of the lanthanide ions in the titania host.

Multisite luminescence of rare earth doped TiO2 anatase nanoparticles

“…These systems are of possible interest in white light emission diode (LED) industry [7e10] and as photocatalysts [11,12]. At the same time, being non-toxic and biocompatible, rare-earth doped anatase has strong potential to replace standard types of fluorophores (quantum dots, organic dyes, etc.…”

Long-lived photoinduced charge-carriers in Er3+ doped CaTiO3 for photocatalytic H2 production under UV irradiation

“…S4). In this sense, Betenelli et al argued that a small fraction of the trapping-detrapping process would be responsible for the lowering of the diffusion coefficient of the photogenerated electrons [19]. In order to confirm the above discussion, the photoluminescence spectra were carried out at room temperature.…”

Upconverting Ho–Yb doped titanate nanotubes

“…The precursor powders of the titanate nanotubes were obtained by sol-gel method [19]. The starting materials were titanium (IV) butoxide (Aldrich, 97%), Yb(NO 3 ) 3 ·5H 2 O (Aldrich, 99.9%), Ho(NO 3 ) 3 ·5H 2 O (Aldrich, 99.9%), absolute ethanol and HCl (37%).…”