Characterization and hydriding properties of Mg-graphite composites prepared by mechanical grinding as new hydrogen storage materials

The characteristics and hydriding properties of novel Mg/G composites as prepared by mechanical grinding (MG) of magnesium metal powder and graphite (G) in the presence of cyclohexane (CH) or tetrahydrofuran (THF) have been studied. The use of graphite led to chemical modifications that improved the hydriding properties of magnesium. The Mg/G composites were more active and effective for hydrogen absorption than reported previously. The additives CH and THF in the MG process influenced strongly the hydriding activity of (Mg/G)(CH) and (Mg/G)(THF), respectively. The quantities of CH and THF required for optimal activity of (Mg/G)(CH) and (Mg/G)(THF) are quite different. For (Mg/G)(THF), MG of 1 h and THF of 6.1 cm(3) gave the best results while the formation of good (MgG)(CH) composites required MG of 20 h and the presence of CH of 12 cm(3). The different influence of CH and THF on the characteristics of the Mg/G composites are also discussed. The composites formed upon grinding in the presence of CH or THF contain finely divided magnesium which is in intimate contact with the aromatic carbon of graphite. This leads to synergetic effects which result in the formation of an effective hydrogen-absorbing material.