Nanostructural Perspective for Destabilization of Mg Hydride Using the Immiscible Transition Metal Mn.

Phase segregation in hydride-forming alloys may persist under the action of multiple hydrogenation/dehydrogenation cycles. We use this effect to destabilize metal hydrides in the immiscible Mg-Mn system. Here, in the MgMn thin films, the Mg and Mn domains are chemically segregated at the nanoscale. In Mn-rich compositions, the desorption pressure of hydrogen from MgH is elevated at a given temperature, indicating a thermodynamic destabilization. The increase in the desorption pressure of hydrogen reaches ∼2.5 orders in magnitude for = 0.30 at moderate temperatures. Such large thermodynamic destabilization allows the MgH to reversibly absorb and desorb hydrogen even at room temperature. Our strategy to use immiscible elements for destabilization of MgH is effective and opens up the possibility for the development of advanced and low-cost hydrogen storage and supply systems.