Individual alumina nanotubes coaxially wrapping carbon nanotubes and nanowires

Al-based anodic porous alumina membranes with ordered nanopore arrays are fabricated for exploring the template synthesis of carbon nanotubes and nanowires. Via the polymerization of acrylonitrile in the ordered nanopores of the membranes and subsequent heating, the polymer structure was converted into a quasi-graphitic structure. Atomic force microscopy observations revealed that the quasi-graphitic nanostructures are located in the pores of the porous alumina membrane, displaying a hexagonal symmetry. Raman scattering investigation confirmed the formation of carbon nanotubes in the nanopores. With further mild, controlled treatment in aqueous alkali and acidic solution, individual alumina nanotubes (ANTs) coaxially wrapping the carbon nanotubes and nanowires are obtained, as evidenced by transmission electron microscopy observations.