Hydrogen storage properties of Mg2Ni affected by Cr catalyst

The effect of Cr as a catalyst in different proportions was investigated to monitor the hydrogen storage properties of Mg2Ni including their thermodynamic aspects. The P–C–T isotherms for absorption/desorption were measured at 225 °C, 250 °C, 275 °C and 300 °C temperatures. A significant increment in the plateau pressures at different temperature was observed, which shows the positive impact of Cr content in the formation of less stable hydrides. The active sites produced by the ball milling may be the reason for the formation of less stable hydrides. Decrements in the storage capacity with the Cr content were attributed to the formation of MgNi2 phase which does not absorb hydrogen at the employed temperature-pressure conditions. XRD and SEM technique were used to identify the structural and morphological changes induced by the hydrogenation cycles. ► In this work, hydrogen storage and thermodynamic properties of Mg2Ni with Cr has been studied. ► Hydrogen storage capacity of Mg2Ni is found to be decreased from 3.56 wt% to 1.81 wt% for high Cr content. ► Enthalpy (−ΔH) is found to be decreased from 54.24 to 39.73 kJ(mol H)−1. ► MgNi2 is supposed to be responsible for formation of less stable hydride as well as for decreased storage capacity.