Superior hydrogen storage properties of Mg_(95)Ni_5 + 10 wt.% nanosized Zr_(0.7)Ti_(0.3)Mn_2 + 3 wt.% MWCNT prepared by hydriding combustion synthesis followed by mechanical milling (HCS + MM)

摘要

Significant improvement of the hydrogen storage property of the magnesium-based materials was achieved by the process of hydriding combustion synthesis (HCS) followed by mechanical milling (MM) and the addition of nanosized Zr_(0.7)Ti_(0.3)Mn_2 and MWCNT. Mg_(95)Ni_5 doped by 10 wt.% nanosized Zr_(0.7)Ti_(0.3)Mn_2 and 3 wt.% MWCNT prepared by the process of HCS + MM absorbed 6.07 wt.% hydrogen within 100 s at 373 K in the first hydriding cycle and desorbed 95.1% hydrogen within 1800 s at 523 K. The high hydriding rate remained well and the hydrogen capacity reached 5.58 wt.% within 100 s at 423 K in the 10th cycle. The dehydrogenation activation energy of this system was 83.7 kJ/mol, which was much lower than that of as-received MgH_2. A possible hydrogenation-dehydrogenation mechanism was proposed in terms of the structural features derived from the HCS + MM process and the synergistic catalytic effects of nanosized Zr_(0.7)Ti_(0.3)Mn_2 and MWCNT.