Photoactive TiO2 Nanopowder Synthesized at Low Temperature without a Catalyst

Nanocrystalline titanium dioxide (TiO2) anatase powder was synthesized at 50 degrees C under normal pressure using the sol-gel method without a base or acid catalyst. The structural and photocatalytic properties of the produced anatase powder were determined with X-ray diffraction, transmission electron microscopy and nitrogen adsorption testing, and compared to those of anatase powder synthesized in a conventional process by calcining at 450 degrees C. The photocatalytic activity was confirmed with methylene blue (MB) discoloration tests. The obtained results showed that the crystal size of anatase produced with the low-temperature catalyst-free method averaged 5.5 nm, while it was 12 nm for the anatase made by calcining. As a consequence, the specific surface area of the anatase powder synthesized at low temperature was three times higher than that of the calcined powder. The weight-based photocatalytic activity of the low-temperature-synthesized powder was 2.5 times higher than that of calcined powder. Therefore, the activity per unit of surface area was slightly higher for calcined anatase.