Fast and continuous obtaining of Eu3+ doped CeO2 microspheres by ultrasonic spray pyrolysis: characterization and photocatalytic activity

• Published in: Journal of materials science. Materials in electronics 2019-06, Vol.30 (12), p.11508-11519
• Main Authors: Santiago, A. A. G., Andrade Neto, N. F., Longo, E., Paskocimas, C. A., Motta, F. V., Bomio, M. R. D.
• Format: Article
• Language: English
• Subjects: Catalytic activity; Cerium oxides; Characterization and Evaluation of Materials; Chemical composition; Chemistry and Materials Science; Conduction bands; Defects; Europium; Fluorite; Lattice vacancies; Materials Science; Microspheres; Morphology; Optical and Electronic Materials; Organic chemistry; Photocatalysis; Raman spectra; Rhodamine; Spectrum analysis; Spray pyrolysis; Ultrasonic testing; Vacancies; X ray fluorescence analysis; X-ray diffraction
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-019-01506-7

In this work, CeO 2 : x Eu 3+ ( x  = 0, 0.01, 0.02, 0.04 and 0.08 mol%) microspheres were obtained by the fast and continuous ultrasonic spray pyrolysis method. Powders were characterized by X-ray diffraction (XRD), X-ray fluorescence analysis (XRF), scanning electronic microscopy (FESEM), Raman spectra, UV–Visible spectroscopy (UV–Vis) and photocatalytic activity. All XRD patterns were indexed by the cubic structure of the fluorite type, without the presence of secondary phases, indicating success in the Eu 3+ doping in the CeO 2 structure. In addition, The XRF analysis confirmed the presence of Eu in the CeO 2 powders. In the Raman spectra of the samples occurs the vibrational mode F 2 g , which is a characteristic band of materials with the fluorite type structure. Moreover, as the Eu 3+ ion increased, it was noticed the appearance of additional bands referring to oxygen vacancies. FESEM showed that the CeO 2 : x Eu 3+ particles have a spherical morphology with homogeneous chemical composition and particle size between 73 and 1560 nm. It can be seen a slight increase of defects in their morphology as the Eu 3+ ion increases. The band gap varies between 3.22 and 3.28 eV, being influenced by defects in oxygen vacancies and the concentration of Ce 3+ ion. The addition of Eu 3+ generates the introduction of intermediary levels in the conduction band of CeO 2 , besides increasing the reactive species effects, favoring the photocatalysis of Rhodamine B dye.