Hydrogen storage properties of transition metals doped fullerides

Carbon based materials,such as fullerides and graphene derivatives,are fascinating systems for solid state H2 storage. Theoretical studies have shown that some metal-decorated fullerides, namelyNa8C60and Li12C60, may absorb up to 9.5 and 13.5 wt% H2 respectively. Recent experimental works proved alkali metal intercalated compounds(Li6C60 andNa10C60) are able to reversibly absorb up to 5 wt% and 3.5 wt% H2 through the formation of a hydrogenated phase of C60 (called “fullerane”) at temperatures higher than 250 °C. Muon spin relaxation studies performed on Li6C60 and Na10C60 samples evidenced that hydrogenation of charged C60 molecules is even more efficient at cryogenic temperatures, suggesting that the high T required for the hydrogen uptake of these materials are required only for the metal cluster assisted H2 molecule dissociation.The insertion of a transition metal able to promote H2 dissociation could therefore decrease the thermal energy required for H2 dissociation and drive the material uptake properties to higher stored values. In this work we describe the new synthesis and the improved H2 sorption behavior (kinetic and thermodynamic features) of Li–fullerides doped with different amounts of Pd and Pt as evaluated by coupled manometric – calorimetric analyses. X-Ray powder diffraction studies were used to describe the hydrogenation mechanism of the compounds.