Interaction of molecular oxygen with single wall nanotubes: role of surfactant contamination

The interaction of molecular oxygen with single wall nanotubes in the form of a commercial bucky paper was investigated by high resolution photoemission spectroscopy. Sodium contamination was found in the sample, which was completely removed only after prolonged heating at 1250 K. The C1s core level spectrum measured on the sample annealed to 1020 K dramatically changed upon exposure to molecular oxygen. On the contrary, when exposing the Na free SWNTs to several KL of O2, the sample remained oxygen free and no modification in the C1s core level was observed. Therefore the observed sensitivity of the sample to O2 was due to a Na mediated oxidation, determining a charge transfer from the C tubes to the Na–O complex.