Synthesis of carbon nanotube/TiO2 composites by titanium evaporation in ultra high vacuum ambient

In this work we present a method for preparing carbon nanotubes/titanium dioxide (CNTs/TiO2) composites with a simple metal vaporization technique in ultra high vacuum ambient at high temperature. We obtain a composite with a highly uniform layer of Ti/TiO2 on CNT and measure exactly the ratio between composites with X-ray Photoemission Spectroscopy (XPS). The obtained Ti–TiO2 film has a thickness of about 1.5 micron and it is perfectly super imposed to carbon nanotubes buckypaper without formation of chemical bonds between tubes and Ti at interface. Comparison between TEM images taken from CNT before and after the treatment indicates the absence of deformation and changes in tube structures. The crystallinity of deposed TiO2 was investigated by Fourier Transform Infrared Spectroscopy (FTIR) which indicate the only presence of anatase. Titanium dioxide is produced by bonds between evaporated Ti atoms and oxygen already adsorbed on carbon nanotubes. Moreover the produced film is very stable and we do not observe changes in Ti percentage after several annealing cycles at high temperatures (500 °C).