The effect of Co dopant on TiO2 structure of sol–gel nanopowders used as photocatalysts

Un-doped and Co-doped sol–gel TiO2 nanopowders have been prepared and structurally characterized. Three Co mass concentrations related to TiO2 content have been used: 0.5, 1 and 2wt%. The morpho-structural changes due to the thermal treatment and dopant presence were followed by: thermal analysis me...

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Bibliographic Details
Published in:Ceramics international 2014, Vol.40 (8), p.12273-12284
Main Authors: Drăgan, Nicolae, Crişan, Maria, Răileanu, Mălina, Crişan, Dorel, Ianculescu, Adelina, Oancea, Petruţa, Şomăcescu, Simona, Todan, Ligia, Stănică, Nicolae, Vasile, Bogdan
Format: Article
Language:English
Subjects:
A. Sol–gel processes
B. X-ray methods
Crystallites
D. TiO2
Dopants
Lattice strain
Nanostructure
Photocatalysis
Photocatalysts
Sol gel process
Solid solutions
Titanium dioxide
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Summary:Un-doped and Co-doped sol–gel TiO2 nanopowders have been prepared and structurally characterized. Three Co mass concentrations related to TiO2 content have been used: 0.5, 1 and 2wt%. The morpho-structural changes due to the thermal treatment and dopant presence were followed by: thermal analysis methods, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and magnetic measurements. A detailed XRD analysis, based on an own calculus program, has established the lattice constants, the average size of the crystallites, , and the average lattice strains, , which can give some information about the structural disorder. The values of the lattice constants lead to the conclusion that a solid solution of the CoxTi1−xO2 form was obtained. The Co concentration imprints the paramagnetic behavior to the solid solutions. It influences the evolution of the and factors by the competition between: the deficit of oxygen acquired by un-doped TiO2 in the sol–gel process (influenced by temperature), the dopant diffusion in the host lattice (influenced by ionic radius and valence) and the super-exchange interactions between the magnetic moments of the molecules of the solid solution (influenced by the concentration of Co). The sample with 1wt% Co thermally treated at 400°C ensures the best photocatalytic activity in the advanced degradation of nitrobenzene from water.
ISSN:0272-8842
1873-3956
DOI:10.1016/j.ceramint.2014.04.072