Effects of Additives on Anatase to Rutile Phase Transformation of TiO2 Powder Synthetized by Sol-Gel Route
N. Belabeda, A. Charia, A. Ayadib, K. Boussninaa, S. Kasouitc
aSemiconductor physico-chemistry laboratory, Department of Physics, University Frères Mentouri Constantine 1, Algeria
bLaboratory of Microstructure and Defects in Materials, Department of Physics, University Frères Mentouri Constantine 1, Algeria
cLam Research Corporation 4300 Cushing Parkway 94538, Fremont, California USA
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The titanium oxide (TiO2) powders were synthesized by a sol-gel route with TiCl4 as a precursor and at ambient conditions. The powders have been dried up at 100° for 12 h and annealed for 1 h at temperatures between 400 and 800°. In the present work, the effects of dissolved ions (e.g., Na+, Cl-, and F-) on the structural particle morphology were investigated using various additives, such as NaCl, NaOH, HCl, and HF. The powders were analyzed by X-ray diffraction and Raman spectroscopy, and the scanning electron microscopy technique was used for agglomerate observations. The photocatalytic activities of the TiO2 powders were evaluated using the degradation reaction of methylene blue. The results show that the presence of Na+ accelerates the transition from anatase to rutile, while that of Cl- and F- delays this transition. The additives modify the pH of the solution and, as a result, the size of the spherical agglomerates constituted of nanoparticles crystalline. These agglomerates are constituted of grains, the size of which depends on the temperature. A more acid solution leads to smaller agglomerates of 0.5 μm size, while a solution that is more basic gives bigger agglomerates. The better photoactivity is obtained in an anatase/rutile mixture with a high fraction of the rutile. Na+ in the TiO2 films affects photocatalytic activity. The surface states on the metal oxide have a considerable influence on the photocatalytic activity with varying pH.

DOI:10.12693/APhysPolA.142.226
topics: TiO2 nanoparticles, sol-gel method, anatase-rutile phases, photocatalytic activity