Synthesis, Luminescent and Antibacterial Properties of Sol-Gel TiO2/TeO2/Nb2O5 Powders

The present paper deals with the synthesis, characterization, and properties of sol-gel-derived TiO2/TeO2/Nb2O5 nanopowders. The gels were prepared using a combination of organic [Ti (IV) n-butoxide, Nb (V) ethoxide (C10H25NbO5)] and inorganic [telluric acid (H6TeO6)] precursors. The aging of gels was performed in air for several days in order to enable further hydrolysis. The phase formation of the gels was investigated by XRD upon heating in the temperature range of 200-700 degrees C. It was established that the gels heat-treated up to 300 degrees C exhibited a predominantly amorphous phase in all binary and ternary compositions. The amount of amorphous phase gradually decreased with increasing temperature, and the first TiO2 (anatase) crystals were detected at about 400-500 degrees C. The average crystallite size of TiO2 (anatase) in the powdered samples heat-treated at 400 degrees C was about 10 nm. By DTA, it was established that the decomposition of organics is accompanied by strong weight loss occurring in the temperature range of 200-300 degrees C. The completeness of the hydrolysis-condensation reactions was verified by IR and UV-Vis analyses. The UV-Vis spectra of the as-prepared gels exhibited red shifting of the cut-off. Photoluminescence spectra exhibited a change in intensity with varying temperature and composition. The performed photocatalytic tests showed that all powders possess photocatalytic activity toward Malachite green organic dye. The obtained nanopowders exhibited good antibacterial properties against E. coli ATCC 25922. The obtained samples can be considered as prospective materials for use as environmental catalysts.