Thermogravimetric analysis of the oxidation of multiwalled carbon nanotubes: Evidence for the role of defect sites in carbon nanotube chemistry

Thermogravimetric analysis (TGA) has demonstrated that multiwalled nanotubes (MWNTs) annealed at 2200 to 2800 degreesC are more air stable than as-produced MWNTs, diamond, graphite, and annealed diamond. The annealed MWNTs are similar in stability to annealed graphite. Defect sites along the walls and at the ends of the raw MWNTs facilitate the thermal oxidative destruction of the nanotubes. Thermal annealing removes these defects, thereby providing MWNTs with enhanced air stability.