Enhanced hydrogen properties of MgH2 by Fe nanoparticles loaded hollow carbon spheres

In the present investigation, we have reported the synergistic effect of Fe nanoparticles and hollow carbon spheres composite on the hydrogen storage properties of MgH2. The onset desorption temperature for MgH2 catalyzed with hollow carbon spheres and Fe nanoparticle (MgH2-Fe-HCS) system has been observed to be 225.9 °C with a hydrogen storage capacity of 5.60 wt %. It could be able to absorb 5.60 wt % hydrogen within 55 s and desorb 5.50 wt % hydrogen within 12 min under 20 atm H2 pressure at 300 °C. The desorption activation energy of MgH2-Fe-HCS has been found to be 84.9 kJ/mol, whereas the desorption activation energies for as received MgH2, Hollow carbon sphere catalyzed MgH2 and Fe catalyzed MgH2 are found to be 130 kJ/mol, 103 kJ/mol, and 94.2 kJ/mol respectively. MgH2-Fe-HCS composite lowered the change in enthalpy of hydrogen desorption from MgH2 by 20.02 kJ/mol as compared to pristine MgH2. MgH2-Fe-HCS shows better cyclability up to 24 cycles of hydrogenation and dehydrogenation of MgH2. The mechanism for the better catalytic action of Fe and HCS on MgH2 has also been discussed.