In this work, we present a study of growth and characterization of nanocomposites, based on multiwalled carbon nanotubes and metal nanoparticles (Al, Ag, Au, Co, Cu, Fe, Ni and Ti). We observe a very different behavior between noble and transitions metals. All the nanocomposites are characterized by a network of carbon nanotubes with randomly insertion of spherical metal particles with dimensions of about 100 nm (clearly visible in SEM images). In particular, in transition metal nanocomposites, each tube on sheet surface is covered by particles of about 40-50 nm and for all metals the XPS measurements indicate the absence of chemical bonds and the simply physisorption of nanoparticle on carbon nanotube buckypaper. Furthermore, the nanocomposites show very different properties respect to pure carbon nanotubes: they are hydrophobic, their roughness is about 50% smaller than carbon nanotube and they exhibit a strong visible photoluminescence, which is absent in pure nanotube.

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The optical and chemical properties of Ag/TiO2nanocomposites were investigated to explore the possibilities of incorporating these new materials in Gratzel photoelectrochemical cells. The nanocomposites were obtained doping TiO2, in both allotropic species anatase and rutile, with silver nanoparticles (grown by laser ablation process). X-ray photoelectron data indicate the absence of Ag-Ti chemical bonds, while measurements of photoluminescence and optical absorbance in UV-visible range show a quench in photoluminescence emission of about 50% and an increase in visible absorbance of about 20%. Measurements of optical band gap, obtained by Tauc’s equation, indicate a variation of about 1.6 eV.

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