This invention provides ways to fabricate nanotubes and nanobead arrays by utilizing nanopores in anodic aluminum oxide (AAO) membranes. Nanotubes of bismuth and other low melting point metals with controlled diameters and lengths can be fabricated by sintering AAO coated with appropriate metals at temperatures above their melting points. Carbon nanotubes may also be readily formed by carbonizing a polymer on the interior walls of the nanopores in AAO membranes. Palladium nanobead arrays which can be used as ultrafast hydrogen sensors are fabricated by coating the flat surface of AAO membranes with controlled pore-wall ratios.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
 The United States Government has rights in this invention pursuant to Contract No. W-31-109-ENG-38 between the United States Department of Energy and the University of Chicago representing Argonne National Laboratory.