The present invention is directed to the production of nanostructures, e.g., single wall carbon nanotubes (“SWNT”) and/or multi-wall carbon nanotubes (“MWNT”), from solutions containing a polymer, such as polyacrylonitrile (PAN). In particular, the invention is directed to the production of nanostructures, for example, SWNT and/or MWNT, from mixtures, e.g., solutions, containing polyacrylonitrile, polyaniline emeraldine base (PANi) or a salt thereof, an iron salt, e.g., iron chloride, and a solvent. In one embodiment, a mixture containing polyacrylonitrile, polyaniline emeraldine base or a salt thereof, an iron salt, e.g., iron chloride, and a solvent is formed and the mixture is electrospun to form nanofibers. In another embodiment, the electrospun nanofibers are then oxidized, e.g., heated in air, and subsequently pyrolyzed to form carbon nanostructures.