Effects of Gas Composition on Highly Efficient Surface Modification of Multi-Walled Carbon Nanotubes by Cation Treatment
1 Department of Materials Science and Engineering, National Chiao Tung University, HsinChu, Taiwan
2 Department of Vehicle Engineering, National Pingtung University of Science and Technology, Neipu, Pingtung, Taiwan
3 Institute of Materials and Systems Engineering, MingDao University, ChangHua, Taiwan
Nanoscale Research Letters 2008, 4:234-239 doi:10.1007/s11671-008-9231-4Published: 16 December 2008
High incident energy hydrogen and/or oxygen cations are generated by electron cyclotron resonance system, and then used to highly efficiently modify multi-walled carbon nanotubes (MWCNTs). The effects of various H2/O2 gas compositions on the modification process are studied. A systematic characterization method utilizing a combination of X-ray photoelectron spectroscopy (XPS), scanning electron microscopy, Raman spectroscopy, and thermogravimetric analysis (TGA) is used to evaluate the effects of various H2/O2gas compositions on MWCNT functionalization. The Raman results show that the ID/IG ratio is directly affected by H2 concentration in gas mixture, and the treatment applying a H2/O2 gas mixture with ratio of 40/10 (sccm/sccm) can yield the nanotubes with the highest ID/IG ratio (1.27). The XPS results suggest that the gas mixture with ratio of 25/25 (sccm/sccm) is most effective in introducing oxygen-containing functional groups and reducing amorphous carbon. The TGA suggests that the structural change of the treated nanotubes is marginal by this method with any gas condition.