Surface-to-Depth Analysis of Functionalized Multi-Wall Carbon Nanotubes (FMWCNTS)

Surface-to-depth analysis of functionalized multi-wall carbon nanotubes, FMWCNT was achieved by the use of high resolution x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometer (SIMS). The pristine nanotubes were functionalized through various steps. These included i) treatment in nitric acid followed by dispersion in dimethylformimide (DMF) and ii) further modification by the linking molecule, 1-ethyl-3-(3-dimethylaminopropyl carbodiimide), (EDC) through covalent attachment. Pristine nanotubes dispersed in DMF, possessed an atomic percentage of oxygen up to 3%, which more than doubled after treatment in nitric acid. After the second functionalization step, the atomic percent of oxygen was lowered relative to nitrogen as some oxygen was possibly displaced by the anchored molecules of EDC. In addition positive ions of CHNH, N2, CO, CH3NH, C2H3O, and negative ions of O, OH, and CN were detected by SIMS. On SIMS depth profiling, the intensity levels of both OH- and CN- ions were found to be steady throughout the 180 sec etch duration, indicating good in depth chemical functionalization of the carbon nanotube structure. Preliminary studies on functionalization of carbon nanotubes by atmospheric pressure dielectric barrier discharges (APDBD) are also reported. Copyright Taylor and Francis 2005