MgH2–ZrFe2Hx nanocomposites for improved hydrogen storage characteristics of MgH2

Abstract The unfavorable de/re-hydrogenation aspects of high storage capacity material, Mg can be overcome by synthesis of composites with known intermetallic hydrogen storage alloys. In this work, a new additive, ZrFe 2 H x intermetallic hydride, is used to synthesize MgH 2 –ZrFe 2 H x nanocomposite by reactive mechanical milling technique. Also this report describes the comparison of hydrogen sorption behavior of MgH 2 –ZrFe 2 and MgH 2 –ZrFe 2 H x nanocomposites. It is found that the composite containing ZrFe 2 and ZrFe 2 H x leads to decrease in desorption temperature from 410 °C (for MgH 2 ) to 350 and 290 °C respectively. The activation energy for rehydrogenation of composite is found to be ∼61 kJ/mol. This is lowered by 30 kJ/mol compared to the pristine milled MgH 2 (92 kJ/mol). Thus, the results show significant improvement of hydrogenation behavior with the addition of ZrFe 2 H x . Reasons for better catalytic activity achieved by using ZrFe 2 H x have been put forwarded. Based on the present studies it can be suggest that the use of hydride version instead of the parent intermetallic phase for synthesizing the composite with MgH 2 has a distinct advantage in improving the hydrogenation behavior of MgH 2 .