Preliminary studies conducted with graphite nanofibers have indicated that the material exhibits a superior performance for the removal of metal ions from low concentration solutions when used as an electrode in an electrochemical cell over that of graphite felts, metal mesh, and other forms of conductive carbon. Furthermore, by application of a reverse potential, the metal species that are bound on the nanofiber surface can be rapidly released into a more concentrated solution for eventual recovery or disposal. Failure to create a practical storage system has up to now prevented hydrogen from reaching the commercial forefront as a transportation fuel. The ideal hydrogen storage unit should be lightweight, compact, relatively inexpensive, safe, and reusable without the need for complex regeneration treatments. While the latter two approaches may offer advantages over the other technologies with regard to cost and safety aspects, they do have their own drawbacks.
Metal hydrides are heavy, expensive, and release heat during the hydrogen absorption process.
It is clear that both storage and controlled release of hydrogen at moderate conditions of temperature and pressure are major issues that must be addressed if this technology is to be exploited on a commercial scale. The ideal solution would be an inexpensive, lightweight material capable of not only absorbing and retaining hydrogen at room temperature and moderate pressures, but also possessing the ability to release the gas at moderate temperatures. One material that fulfills this requirement is graphite nanofiber. Data obtained in our laboratory has demonstrated that when these structures are pretreated under conditions whereby all adsorbed and absorbed gases are eliminated, then on subsequent exposure to hydrogen at moderate pressures, they are capable of absorbing and retaining up to 30 liters of molecular hydrogen per gram of carbon at room temperature . Theoretical calculations made on the hydrogen absorption capacity of single-crystal graphite have indicated that it is possible to store 6.2 liters of molecular hydrogen per gram of graphite as a single flat layer.