PURIFICATION OF CARBON FILAMENTS AND THEIR USE IN STORING HYDROGEN

摘要

Carbon structures, e.g. carbon nano-fibers, suitable for absorbing hydrogen at low pressures and low temperatures are produced by a selective oxidation and/or acid reflux process. The process includes heating an impure mixture containing a crystalline form of carbon in the presence of an oxidizing gas at a temperature and time sufficient to selectively oxidize and remove a substantial amount of any amorphous carbon impurities from the mixture. Metal containing impurities can be removed from the mixture by exposing the desired carbon and accompanying impurities to an acid to produce a carbon fiber that is substantially free of both non-fiber carbon impurities and metal impurities. Another aspect of the present invention includes purified carbon structures that can store hydrogen at low pressures and temperatures.