Fuctionalization of Single-Walled Carbon Nanotubes with Organo-Lithium Compounds: A Combined XPS, STM, and AFM study

摘要

A covalent sidewall functionalization of Single-Walled Carbon Nanotubes (SWCNTs) has been achieved by a reaction with butyllithium in benzene. The nucleophilic attack of the lithium organyl leads to a transfer of nagative charge to the SWCNTs which is balanced by the positive charge of the Li-ions. In our investigation we were able to verify the negative charge on the SWCNTs by a concomitant shift of the binding energy of the C 1s core levels of the SWCNTs in X-ray induced photoelectron spectroscopy (XPS). Moreover, scanning tunneling microscopy (STM) reveals a decoration of the tubewalls by features which exhibit the expected threefold symmetry of the butyl-groups. The charging of the SWCNTs in solution could also be verified by applying a homogeneous electric field using Au coated glass electrodes. The electrodes were chraracterized by XPS and atomic force microscopy (AFM). These measurements reveal the appearance of Li on one electrode, and the occurance of SWCNTs on the counter electrode.