In this work, we report on the optoelectronic and photocatalytic features of europium (Eu3+)-doped TiO2 nanoscale particles synthesized via a sol-gel mediated rapid-condensation technique. X-ray diffraction studies have revealed the mixed phases of the synthesized systems. In particular, a mixture of anatase, brookite, and rutile phases was found to coexist beyond a sintering temperature of 600 °C while a pure anatase phase was witnessed below 500 °C. The photoluminescence spectra of ∼7 nm sized anatase TiO2 nanoparticles have exhibited different intra 4f (Eu3+ ion related) transitions with the most intense red emission (5D0→7F2) peak located at ∼613 nm. The emissions due to color centers and oxygen vacancies of TiO2 were also evident in the PL spectra. The Brunauer-Emmett-Teller surface area analysis has revealed a significant increment of surface area and pore volume owing to the enhanced interfacial region introduced by point defects and dislocations due to Eu doping. The photocatalytic activity of the Eu3+ doped TiO2 nanoscale system was found to be ∼12% stronger than its un-doped counterpart, as assessed from the degradation of methyl orange (MO) solution under UV light irradiation. The percentage of degradation was found to be strongly dependent on the duration of the UV exposure and Eu doping concentration. As an efficient photosensitive candidate, rare earth sensitized TiO2 systems would bring new insights while displaying both optoelectronic and photocatalytic characteristics through use of the localized states present in the band gap of the host.
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One of the authors (NP) acknowledges DST, New Delhi for providing fellowship through INSPIRE scheme. We thank SAIF, NEHU, Shillong for extending TEM facility. NP would like to thank Ms. Giti Das for her assistance during synthesis steps. The authors also thank Prof. R.C. Deka, Dr. G.A. Ahmed, and Ms. Rasna Devi for their help and support in BET surface analysis through N2 adsorption/desorption study. A part of the work was carried out through project no. UFR-50307/2011 supported by IUAC, New Delhi.
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Paul, N., Mohanta, D. Effective optoelectronic and photocatalytic response of Eu3+-doped TiO2 nanoscale systems synthesized via a rapid condensation technique. Journal of Materials Research 28, 1471–1480 (2013). https://doi.org/10.1557/jmr.2013.122