Relationship between Carbon Nanotube Structure and Electrochemical Behavior: Heterogeneous Electron Transfer at Electrochemically Activated Carbon Nanotubes |
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| Authors: | Martin Pumera Dr Toshio Sasaki Hideo Iwai Dr |
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| Institution: | 1. Biomaterial Systems Group, Biomaterials Center and International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Nanomaterials & Biomaterials Research Building, 1‐1 Namiki, Tsukuba, Ibaraki (Japan), Fax: (+81)?29‐860‐4706;2. High Voltage Electron Microscope Laboratory, Eco‐Topia Science Institute, Nagoya University, Furo‐Cho, Chikusa‐ku, 464‐0814 Nagoya (Japan);3. Materials Analysis Center, National Institute for Materials Science, 2‐1 Sengen, Tsukuba, Ibaraki (Japan) |
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| Abstract: | The electrochemical activation of multiwalled carbon nanotubes (MWCNTs) (at potentials of 1.5–2.0 V vs Ag/AgCl for 60–360 s) results in significantly increased rate constants ( ) for heterogeneous electron‐transfer with Fe(CN)6]3?/4? (from 8.34×10?5 cm s?1 for as‐received MWCNTs to 3.67×10?3 cm s?1 for MWCNTs that were electrochemically activated at 2.0 V for 180 s). The increase in the value of  arises from the introduction of wall defects exposing edge planes of the MWCNTs, as observed by high‐resolution TEM. The density of the edge plane defects increases from almost zero (for as‐received MWCNTs) to 3.7 % (for MWCNTs electrochemically activated at 2.0 V for 180 s). High‐resolution X‐ray photoelectron spectroscopy (HR‐XPS), Raman spectroscopy, and electrochemical impedance spectroscopy were used to gain a better understanding of the phenomena. HR‐XPS revealed that the increase in electrochemical activation potential increases the number of oxygen‐containing groups on the surface of carbon nanotubes. |
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| Keywords: | carbon nanotubes electrochemistry electron transfer nanostructures photoelectron spectroscopy |
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