Synthesis and Characterization of Fullerene-based Hydrogen Storage Materials

Storing hydrogen safely and efficiently is an area of great interest for the utilization of hydrogen as an energy carrier in transportation applications. The feasibility of using fullerenes in hydrogen storage materials was investigated. Alkali decorated fullerenes Li_xC₆₀ [LixC60] and Na_xC₆₀ [NaxC60] were found to enhance the hydrogen chemisorption and physisorption properties of fullerenes. Although the overall hydrogen physisorption uptake in these materials is low due to the crystalline nature of the material, the isosteric heats of adsorption of fullerenes were increased by lithium doping. C₆₀ [C60] is also capable of acting as a catalyst in the dehydrogenation and rehydrogenation of lithium borohydride. Evidence for hydrogenated fullerenes (fulleranes) in the LiBH₄:C₆₀ [LiBH4:C60] nanocomposite gives evidence for the catalyzation mechanism of LiBH₄ [LiBH4] to involve the surface of the fullerene. This effect is unlike other carbon materials used for kinetic enhancement in that it does not solely rely on nanoconfinement and particle size reduction to enhance the hydrogen storage properties of complex metal hydrides. The addition of C₆₀ [C60] to lithium borohydride resulted in a reduced dehydrogenation temperature, increased hydrogen desorption kinetics, and reversibility of hydrogen adsorption under much milder conditions than pure LiBH₄ [LiBH4]. Characterization of hydrogenated fullerenes by various mass spectrometric techniques (LDI-TOF-MS, SPALDI-TOF-MS, MALDI-TOF-MS, and APPI-MS) and the advantages of each technique is reviewed. Furthermore, initial findings on the catalyzation of lithium amide and hydrogenated lithium nitride with iridium, in which the dehydrogenation temperatures and ammonia emission are reduced, is discussed.