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

• Published in: Ceramics international Vol. 40; no. 8; pp. 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: Journal Article
• Language: English
• Published: Elsevier Ltd 2014
• 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; B. X-ray methods; A. Sol–gel processes; Photocatalysts; D. TiO2
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2014.04.072

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.