Enhanced Hydrogen Storage Performance of MgH2 by the Catalysis of a Novel Intersected Y2O3/NiO Hybrid

MgH2 is one of the most promising hydrogen storage materials due to its high hydrogen storage capacity and favorable reversibility, but it suffers from stable thermodynamics and poor dynamics. In the present work, an intersected Y2O3/NiO hybrid with spherical hollow structure is synthesized. When introduced to MgH2 via ball-milling, the Y2O3/NiO hollow spheres are crushed into ultrafine particles, which are homogenously dispersed in MgH2, showing a highly effective catalysis. With an optimized addition of 10 wt% of the hybrid, the initial dehydrogenation peak temperature of MgH2 is reduced to 277 °C, lowered by 109 °C compared with that of the bare MgH2, which is further reduced to 261 °C in the second cycle. There is ca. 6.6 wt% H2 released at 275 °C within 60 min. For the fully dehydrogenation product, hydrogenation initiates at almost room temperature, and a hydrogenation capacity of 5.9 wt% is achieved at 150 °C within 150 min. There is still 5.2 wt% H2 desorbed after 50 cycles at a moderate cyclic condition, corresponding to the capacity retention of 79.2%. The crystal structure and morphology of the Y2O3/NiO hybrid is well preserved during cycling, showing long-term catalysis to the hydrogen storage of MgH2. The Y2O3/NiO hybrid also inhibits the agglomeration of MgH2 particles during cycling, favoring the cyclic stability.

Study of a highly porous composite material based on an aluminum matrix with an ordered cellular structure formed by hollow copper-graphite spherical granules

The structure and properties of a highly porous cellular composite material based on a framework of hollow spherical granules with a thin copper-graphite coating impregnated with an aluminum alloy have been investigated. Highly porous composite composite casting with molten form, filled with expanded polystyrene spherical granules with a thin copper-graphite layer applied to their surface. When the polymer core of the granules burns out in the casting, a highly porous cellular composite material is formed with an aluminum matrix filled with spherical pores ∅ 4 – 8 mm, adjoining the metal matrices through a thin (300 – 500 μm) copper shell. The density of the porous composite material obtained in this way is 1.67 g/cm3. In order to fill the space between the granules with aluminum melt, their surfaces were coated with a thin layer of titanium, molybdenum, or chromium borides, which positively affected the strength characteristics of the composite material as a whole. Estimated calculation of the shock absorber index of a new highly porous structural material based on aluminum matrices with a cellular structure made of spherical hollow granules regularly distributed over the volume proved the prospects of its subsequent use as an absorber of shock energy in shock-absorbing devices.