XPS characterization of MWCNT and C₆₀-based composites

Abstract

X-ray photoelectron spectroscopy was used for characterization of MWNT-C60 composites with assistance of scanning and transmission electron microscopy. The composites were received by immerison of nanotubes into fullerene solution in CS2 with consequent processing with green laser irradiation at aproximately 10 W/cm2. It was shown that C1s spectra of composites are different from simple addition of MWNT and C60 features. It found that preliminary nanotube purification by oxidative treatment influences strongly the nature of fullerene-nanotube bonding. Hydrophilic surface of oxidized nanotube material has lower affinity to C60 molecules and provides for concentration of C60 molecules into clusters, which show differential charging effect in XPS spectra. The differential charging effect disappears after laser processing, which induces photopolymerization of fullerene clusters. The as-synthesized nanotubes form composites with more evenly distributed fullerene.