Synthesis of vertically aligned CNTs with hollow channel on Al2O3-Al substrate electroplated with fe nanoparticles

The vertically aligned carbon nanotube (VA-CNT) arrays, in which all individual nanotubes possessed totally hollow channels, were first control prepared in a large amount on Al2O3-Al substrate electroplated with Fe nanoparticles. The comparison of addition or no addition of Mg species in the electroplating solution was found to be crucial to controlling the channel structure of CNTs. Generally, bamboolike VA-CNT arrays were produced in the process without Mg addition, in contrast to the VA-CNT arrays with totally hollow channels by adding Mg. Such results revealed the easy sucking of Fe nanoparticles into the nanotube channel via the capillary filling effect. And the tuning of the metal-substrate interaction by Mg, as forming MgAl2O4 spinel structure, was effective to stabilize Fe nanoparticles on the substrate and consequently to produce nanotubes with hollow channels. The cheap Al2O3-Al substrate allows the preparation of such arrays in a large area, which may be easily used to construct nanoscale catalytic reactors or to prepare CNT-polymer membranes with known pore characterization. (C) 2008 The Electrochemical Society.