NANOSTRUCTURED METAL-DOPED TIO2 THIN FILMS

Simina Dreve1,a, E. Indrea1,bDan T. Silipas1, Nascu Horea-Iustin2

1National R&D Institute of Isotopic and Molecular Technologies, P.O. Box 700, R-3400 Cluj-Napoca , Romania
2 Technical University of Cluj-Napoca, Romania
a simina@s3.itim-cj.ro , beindrea@s3.itim-cj.ro

One of the major goals behind designing metal semiconducting nanocomposites is to improve the catalytic properties or to tune the luminescent or sensing properties. Nanoscale metal particles dispersed on nanosized TiO2 support exhibit remarcable specific structures and properties. There are different strategies that have been adopted with the aim to increase the response of the material to visible light and/or increase its efficiency in photo-oxidation processes. In the present work, we report on material modification by doping with small amounts of metal impurities. As an example, while inert as bulk material, gold nanoparticles dispersed on semiconducting oxides surface have a very important catalytic activity [1]. During the early years of photocatalysis it was shown that the photoinduced deposition of noble metals such as Pt or Au on semiconductor nanoclusters enhance their photocatalytic activity [2,3].
 With a view to the development of eco-friendly photoacatalytic surfaces, this work examines metal-doped TiO2-based materials, where the semiconducting oxide is doped by low amounts of metal ions.
The preparation of metal-doped TiO2 composite thin layer on glass surface have been realised by preparing separately the stock solutions of doping metals and the sol of nanostructured TiO2, followed by the two solutions mixing.
The sol of nanostructured TiO2 (Degussa-P25) was prepared by grinding in a mortar the titanium dioxide powder with water, poly-ethylene-glycol and acetyl-acetone [4]. The mixture of gold-titanium dioxide was obtained by mixing the two stock solutions, as the final metal concentration is 10-3 M.
It is shown that transparent preparations of anatase titanium dioxide (nanostructured TiO2), doped with metals when applied on glass, can preserve the original appearance of the surface, without altering the characteristics of the material. In order to determine the microstructural metal nano-crystallites X-ray diffraction technique was used to microstructure characterization of nanocystalline metal-TiO2 composite [5]. 

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