Sensitivityof single wal carbon nanotubes to oxidative processing:structural modification,intercalation and functionalisation

摘要

The effect of oxidation on modification of single wall carbon nanotubes (SWCNTs)through succssive purification steps has been studied.The efficient eliminatin of metal impurities has been follwoed by induced coupled plasma spectroscopy.Upon acid treatment,Raman spectroscopy clearly proofed that HNO_3 molecules wee intercalated into the bundles of SWCNTs.At the same time,SWCNTs also have suffered a high degree of degradation and defects were interoduced.The subsequent thermal processes led to the removal of further defect carbon materials and to the almost complete deintercalation of the HNO_3 molecules.Changes in the structure of the SWCNT bundles have been observed by transmission electron microscopy.While bundles tend to separate upon acid treatment,after the complete purification process,the remaining SWCNTs tend to form thick bundles again.The existence of functiona groups in the raw single wall carbon nanotubes material and their modification and almost complete removal after the final annealing step has been studied by Fourier transform infrared spectroscopy,X-ray photoelectron spectroscopy and temperature programmed desorption.Nitrogen adsorption isotherms analysed according to Brunauer-Emmet-Teller showed important changes in the pore volume and surface area through the purifiation steps.