NOVELTY - Depositing a contiguous noble metal thin film on carbon nanostructures involves oxidizing a surface of carbon nanostructures; forming a dipole at the surface of the carbon nanostructures; adsorbing metal ions (3) on surface of carbon nanostructures; reducing the adsorbed metal ions; and immersing the carbon nanostructures in a solution containing a salt of at least one noble metal to form thin film of noble metal (4).    USE - For depositing a contiguous noble metal thin film on carbon nanostructures (claimed), used in fuel cells, batteries, and other electrochemical processes or energy storage devices.    ADVANTAGE - Since conventional carbon nanotubes are only a few nm in diameter, access to inner wall surfaces is highly physically constrained. On the other hand, carbon nanohorns are open-ended, thus by making a larger fraction of their surface available as reaction sites. When spherical aggregates of carbon nanohorns are assembled into a three-dimensional network, fine pores on the order of tens of nanometers are formed between the aggregates themselves. These pores are larger than that found in activated carbon (which are typically only a few nm), thus permitting greater physical access to intrapore surfaces. In addition to the increase in accessible surface area, carbon nanohorns have the added advantage of ease of synthesis since they can be easily fabricated without the aid of a catalyst. The larger pore size of carbon nanotubes and nanohorns enables the deposition of thin conformal metal or oxide films on the surfaces of these nanostructures. The metals and their oxides can further improve the capacitance by improving the electrostatic charge storage capability (for non-Faradaic capacitors) of the surface, acting as a catalyst to facilitate chemical surface reactions (for Faradaic capacitors), and/or lowering the internal resistance of the electrodes.    DESCRIPTION OF DRAWING(S) - The figure shows sequence of steps and accompanying surface chemical reactions which leads to deposition of a monatomic layer of the desired noble metal.    Carbon (1)    Oxygen (20)    Metal ions (3)    Noble metals (4)