Surface characterizations of carbon multiwall nanotubes: Comparison between surface active sites and Raman Spectroscopy

In carbon nanotubes and nanofilaments, the surface properties play a fundamental role for any use or application. It is therefore necessary to know and to control their surface characteristics, which are dependent on the fabrication process and surface treatments. In this work, two selected series of multiwalled nanotubes on which a thermal treatment and/or a controlled surface oxidation, using nitric acid solutions, have been carried out. The structural changes of the nanotubes due to these treatments have been followed by means of two different approaches: first, a solid-state chemistry approach with the determination of chemical surface properties of the carbon characterized by the active surface area (ASA) concept and, second, a more physical approach with Raman inicrospectroscopy. With this track, it was possible to quantify the surface/morphology ratio in nanotubes, especially in relation with their wettability and adhesion. Hence, we have established a general relationship between physical and chemical approaches that should be valid for any mesoporous, and even macroporous, carbons.