New carbon multiwall nanotubes – TiO2 nanocomposites obtained by the sol–gel method

Carbon nanotubes-anatase nanocomposites obtained by the sol–gel method could be interesting materials due the semiconducting properties of TiO2. In the present study, nanotubes, produced by catalytic decomposition of acetylene, were covered with a TiO2 thin layer or with TiO2 nanoparticles obtained by the sol–gel method. In the sol–gel process, two different classical alkoxides were used: titanium tetra-ethoxide and titanium tetra-isopropoxide with or without addition of cetyltrimethylammonium bromide as surfactant. Thermal treatment removes organic moieties and allows TiO2 crystallization as anatase on the nanotubes surface. Without surfactant, the TiO2 crystallized as a thin film or as nanoparticles on the nanotubes surface. In the presence of a surfactant, the rate of anatase crystallization was observed to decrease.