Effects of nitrogen-doping on the microstructure, bonding and electrochemical activity of carbon nanotubes

Vertically aligned carbon nanotubes produced with in-situ doping of nitrogen (CNx NTs) during chemical vapor deposition exhibit unique structural and electrochemical properties, which are strongly correlated with their nitrogen (N) doping level. In this work, the effects of N-doping on CNx NTs have been systematically investigated via microstructure and bonding studies, electron-transfer (ET) behaviors, and subsequent electrochemical deposition of catalyst. The CNx NTs doped with an optimal N level, while showing a nearly reversible ET behavior, in fact exhibit uniform and high density of surface defects. These surface defects are desirable for further modification and/or nucleation of catalytic particles on the surface of CNx NTs to form a composite electrode for electrochemical energy device applications such as fuel cells and capacitors.