Nanodevices that explore the synergies between PDCs and carbon nanotubes

There is now good evidence that carbon nanotubes can be coated uniformly with a very thin, perhaps even a monolayer, of a polymer-derived ceramic (SiCN) by a simple process of soaking the nanotube surfaces with the liquid precursor followed by pyrolysis. The ceramic coating bonds the nanotubes to one another, which suppresses time-dependent creep that is present without the ceramic bonding. In this article we address the influence of the ceramic coating on two functional properties of carbon nanotube structures-the electrolytic supercapacitance and electrochemico-mechanical actuation. The results, when expressed as the equivalent surface capacitance of carbon sheets, are quite unexpected. The ceramic coating appears to increase the surface capacitance of the nanotube structure. The actuation induced by capacitive charging is also shown to be somewhat enhanced, although the principal influence of the coating is to suppress the drift of the actuation seen in unbonded carbon nanotube structures. It is inferred that the thickness of the SiCN coating amounts to approximately one monolayer of coverage of the nanotubes. (C) 2004 Elsevier Ltd. All rights reserved.