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Hydrogen desorption and absorption properties of magnesium borohydride (Mg(BH4)2) were studied for three cycles. Effect of cobalt additives and their local structure upon cycling were investigated in detail.

The decomposition and rehydrogenation of γ-Mg (BH 4 )

Nanoconfined 2LiBH4–MgH2 is prepared by direct melt infiltration of bulk 2LiBH4–MgH2 into an inert nanoporous resorcinol–formaldehyde carbon aerogel scaffold material. Scanning electron microscopy (SEM) micrographs and energy dispersive X-ray spectroscopy (EDS) mapping reveal homogeneous dispersion of Mg (from MgH2) and B (from LiBH4) inside the carbon aerogel scaffold. Moreover, nanoconfinement of LiBH4 in the carbon aerogel scaffold is confirmed by differential scanning calorimetry (DSC). The hydrogen desorption kinetics of the nanoconfined 2LiBH4–MgH2 is significantly improved as compared to bulk 2LiBH4–MgH2. For instance, the nanoconfined 2LiBH4–MgH2 releases 90% of the total hydrogen storage capacity within 90 min, whereas the bulk material releases only 34% (at T = 425 °C and p(H2) = 3.4 bar). A reversible gravimetric hydrogen storage capacity of 10.8 wt % H2, calculated with respect to the metal hydride content, is preserved over four hydrogen release and uptake cycles.

In-situ synchrotron radiation powder X-ray diffraction (SR-PXD) technique is a powerful tool to gain a deeper understanding of reaction mechanisms in crystalline materials. In this paper, the implementation of a new in-situ SR-PXD cell for solid-gas reactions is described in detail. The cell allows performing measurements in a range of pressure which goes from light vacuum (10-2 bar) up to 200 bar and temperatures from room temperature up to 550°C. The high precision, with which pressure and temperature are measured, enables to estimate the thermodynamic properties of the observed changes in the crystal structure and phase transformations.

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