Low-temperature catalytic oxidation of multi-walled carbon nanotubes

When in a pure form, carbon nanotubes are known to be stable in air up to ∼800 K making them attractive for a large variety of applications. In this work, we report a significant decrease of ignition temperature (in some cases occurring at ∼500 K) and a reduction in the apparent activation energy for oxidation in air as a result of impregnation with nanoparticles (<2 nm) of metal (Pt, Pd, Ni and Co) acetylacetonates or by decoration with corresponding oxides. Surprisingly, defects introduced by partial oxidation of the carbon nanotubes do not in practice have any influence on the enhancement of further oxidation. Reduction temperatures of metal oxides with H2 were close to those of other carbon supported catalyst materials. However, the carbon nanotubes showed a tendency for low temperature gasification in the presence of hydrogenation catalyst metals (Pt, Pd).