Hydrogen sorption properties for surface treated MgH2 and Mg2Ni alloys

In our group, strong enhancement of the hydrogen sorption capacities and kinetics of Mg and intermetallic alloys was recently achieved by surface treatments using physical and chemical means separately or in convert. In the latter, our approach consists in the preparation of tailor-made composites by ball-milling the alloy with preground graphite using specific milling conditions, followed by the deposition of Pd nanoparticles on the alloys surface using the polyol process. The benefit of graphite was ascribed to the carbon coating leading to the protection of the reactive metallic particles toward oxidation and the reduction character of carbon cleaning the alloy surface of NiO. Finally, the fine Pd particles deposited at the metallic surface probably act as hydrogen pumps during the desorption process. By combining both techniques, a hydrogen desorption as high as 3 wt.% in 60 min at 150 ° C and 6.2 wt.% in 30 min at 300 ° C are obtained for surface treated Mg2Ni alloy and MgH2, respectively. The latter treatment for MgH2 is compared with the deposition of CeO2 doped 6 at.% of Pt.