X-ray photoelectron spectroscopic studies of surface modified single-walled carbon nanotube material

X-ray photoelectron spectroscopy (XPS) has been used to investigate the sur face chemical state of two carbon nanotube materials and determine the evid ence of surface modification from a reaction with dichlorocarbene. Carbon a nd oxygen were the major elements observed on the surface of the pristine c arbon nanotube produced by electric arc discharge. After reaction with dich lorocarbene, chlorine atoms amounting to about 1.6 at.% were detected and t he peak position of Cl 2p was at 201.3 eV, which can be attributed to exist ence of organic chlorocarbons. A new intense peak addition to the peak at 2 85 eV for the elemental sp(2) and sp(3) carbon atoms appears at the binding energy of about 287.5 eV in the C 1s narrow scan spectrum. This binding en ergy is typical for C 1s ionization of sp(3) carbon in organic chlorocarbon s. It was found that C-C was the major carbon functional component in the s urface modified carbon nanotube but other functional forms of carbon were a lso present such as C-Cl, C-O, and O-C=O. With Ar+ ion sputtering, the atom ic percent concentration of chlorine decreased by 65%, the carbon concentra tion increased significantly and the oxygen surface concentration decreased from 20.7 to 5.5 at.%. The surface chemical treatment with dichlorocarbene has thus modified the surface of the carbon nanotube with localization of small amounts of chlorine atoms on the carbon surface without disrupting th e single walled nanotube bundles. (C) 2001 Elsevier Science B.V. All rights reserved.