Gold nanoparticles have been utilized for centuries by artists due to the vibrant colors produced by their interaction with visible light. More recently, these unique optoelectronic properties have been researched and utilized in high technology applications such as organic photovoltaics, sensory probes, therapeutic agents, drug delivery in biological and medical applications, electronic conductors and catalysis. The optical and electronic properties of gold nanoparticles are tunable by changing the size, shape, surface chemistry, or aggregation state.

The control of the particle sizes that can be achieved is due to the choice of synthetic methods and the careful application of operating conditions. Thus, researchers have developed a new method for preparing Au / TiO₂ catalysts by deposition-precipitation with urea [1, 2]. This method gives the same gold nanoparticle size as that obtained by Haruta with the deposition-precipitation method with NaOH [3], while allowing a higher gold loading. In the present study, we studied gold nanoparticles supported on titanium oxide, prepared by impregnation with ionic exchange. In the first stage, the conditions of fixing the metal precursor on titanium oxide are optimized. In the second stage, the samples are calcined at various temperatures (T=250, 350, 500C). Several experimental techniques are used for the characterization of the samples at the various stages of their elaboration (MEB, DRX, FTIR). A change of morphology of the oxide titanium grains was observed by Scanning Electron Microscope. The X-rays diffraction made it possible to evidence the formations of nanoparticles of gold sized 3 nm in the case of catalysts Au/TiO₂ calcined at 250C.At superior temperature, its size increases following the phenomenon of coalescence.

Key words : Nanoparticules, Au, TiO₂, catalysis.

References:

[1] S. Tsubota, M. Haruta, T. Kobayashi, A. Ueda, Y. Nakahara. (1991). Studies in Surface Science and Catalysis, 72, 695-704.

[2] Hayato Yuzawa, Tomoko Yoshida, Hisao Yoshida. (2012). Applied Catalysis B: Environmental 115 116, 294 302

[3] S. Tsubota, D. A. H. Cunningham, Y. Bando, M. Haruta, (1995). Studies in Surface Science and Catalysis, 91, 227-235.