T. Gavasheli, G. Mamniashvili, M. Nadareishvili, T. Zedginidze
Ivane Javakhishvili Tbilisi State University,
Keywords: renewable energy, nanotechnology, photocatalysis, titanium oxide, cobalt nanoclusters, cobalt nanowires, magnetometry, optical spectrometry
Summary:Photocatalysis decomposition of water into hydrogen and oxygen under the effect of sunlight is one of promising trends in finding the alternative energy sources. Water is not split by sunlight immediately. Currently titanium dioxide TiO2 is a promising photocatalyst for this purpose. In this substance electron-hole pairs, formed under the effect of solar rays on the photocatalyst surface interact with water molecules and split them into hydrogen and oxygen. Hence photocatalysts are used in the form of fine powder, to increase the surface area. Here comes a new problem: reaching the surface of a fine particle pairs undergo recombination very quickly. That is why it is necessary to coat the particles surface with nanoclusters which capture electrons or holes and hinder their recombination. At Andronikashvili Institute of Physics at TSU, a novel method for electroless (chemical) deposition of nanoclusters of different substances on the surface of nanopowders was developed. The specific feature of this method is that the deposition proceeds at low temperature. Therefore, the method is simple and low-cost, it changes neither the properties of the matrix nor those of the material to be deposited. With this method, Co nanoclusters were deposited on TiO2 micro- (44 m) and nano- (10 nm) powders. The magnetometry and optical spectroscopy measurements of the photocatalytic activity of these micro- and nanopowders coated by Co nanoclusters were carried out. It was found that the TiO2 nanopowders are more suitable for photocatalysis not only because they have a larger specific surface area but also the specific efficiency of nanopowders is much higher than that of micropowders. It is shown also that this electroless deposition method could be effectively used for the production of cobalt nanopowders and nanowires having great scientific and technology importance due to their unique properties different from the bulk. Simple magnetometry methods are proposed to control their magnetic properties.