Thermodynamic and electrochemical properties of nanocrystalline Mg2Cu-type hydrogen storage materials

Mechanical alloying (MA) process was used to synthesize the nanocrystalline Mg2Cu and nanocomposite Mg2Cu/Pd hydrogen storage materials. The structure of these materials has been examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Thermodynamic and electrochemical properties have also been investigated. The mechanical alloying for 18 h led directly to the formation of the orthorhombic-type structure with a crystallite sizes of about 30 nm. The results show that the maximum absorption capacity reaches 2.25 wt.% for nanocrystalline Mg2Cu alloy. This is lower than in the polycrystalline Mg2Cu alloy (2.6 wt.%) because of a significant amount of strain, chemical disorder and defects introduced into the material during the mechanical alloying process. On the other hand, mechanically coated Mg2Cu alloy with palladium has effectively reduced the degradation rate of the studied electrode material.