Electrochemistry of Controlled Diameter Carbon Nanotube Fibers at the Cross Section and Sidewall

Electrochemistry at open ends and sidewalls of carbon nanotubes (CNTs) has been under debate, with opposing viewpoints as to which sites are more electrochemically active. A particular challenge in this field has been the ability to conduct electrochemical studies at the open ends of CNTs, without measuring contributions from the sidewalls. Here, we report on electrochemical measurements taken from the sidewall of highly densified multiwalled carbon nanotube fibers (HD-CNTf) and the cross section (i.e., open ends) of highly densified multiwalled carbon nanotube fibers (HD-CNTfs) embedded in a polymer matrix. The cross section of the HD-CNTfs was exposed to reveal only open ends to the electrolyte interface, and this platform allowed us to compare electrochemistry at the open ends and sidewalls of HD-CNTfs. Cyclic voltammetry was employed to examine the electrochemical properties of HD-CNTfs by using a conventional bulk electrochemical cell and microcapillary electrochemical measurements. The cross sections and sidewalls of HD-CNTfs are shown to promote similar electron transfer kinetics and electrochemical activity.