Metal-nanocluster-filled carbon nanotubes: Catalytic properties and possible applications in electrochemical energy storage and production

Ensembles of highly aligned and monodisperse graphitic carbon nanotubules have been prepared via the template method using chemical vapor deposition of carbon within the pores of alumina membranes. Tubules with diameters of 200 nm have been prepared, and smaller diameters are possible. Free-standing aligned carbon-tubule membranes are formed by this template method. These novel carbon tubule membranes can be filled with nanoparticles of electrocatalytic materials (i.e., Pt, Ru, Pt/Ru), which can then be used to electrocatalyze O-2 reduction and methanol oxidation as well as the gas-phase catalysis of hydrocarbons. Hence, these membranes have potential applications in fuel cell development. Smaller, highly ordered graphitic-carbon tubules can also be prepared within the template-synthesized carbon tubules, using Fe nanoparticles as catalysts. In these novel tube-in-tube structures, both the outer and the inner tubules are electrochemically active for Li+ intercalation, suggesting possible applications such as Li ion battery anodes.