Effect of fuels on combustion synthesis of TiO2 - Towards efficient photocatalysts for methylene blue oxidation and Cr (VI) reduction under natural sunlight

A facile synthesis of carbon and nitrogen co-doped nano-TiO2 with pure anatase phase and high surface area was achieved by using combustion synthesis without the need of surfactants in a single step approach. Organic fuels such as hexamine, triethyl amine and glycine were tested as different fuels with titanylnitrate as the common oxidant. Effect of mixture of fuels has also been studied by taking the combinations of the above mentioned fuels. X-ray diffraction confirms the anatase phase titania and nano-crystalline size of the prepared catalysts was confirmed by transmission electron microscopy (TEM). N-2 adsorption confirmed the high surface area of nanocrystalline titania. Red shifts in UV-Vis absorption spectra was assigned due to the C and N-doping into the TiO2 matrix, whereas the presence of C and N in the TiO2 matrix was confirmed by X-ray photoelectron spectroscopy. Photocatalytic activity of the catalysts has been estimated from the oxidation of methylene blue (MB) and reduction of Cr (VI) under natural sunlight in open atmosphere. Among the TiO2 catalysts prepared, the one obtained with glycine as the fuel showed the best photocatalytic activity, which was correlated to the number of moles of gases evolved during the synthesis. (C) 2013 Elsevier B.V. All rights reserved.