Hydrogen storage in 2NaBH4 + MgH2 mixtures: Destabilization by additives and nanoconfinement

We focus on the H2 desorption properties of the 2NaBH4 + MgH2 system destabilized by different methods. Nanostructured powder mixtures were prepared by ball milling the starting hydrides and nanoconfined reactive composites were obtained by melting infiltration of the hydrides into a Si-based SBA-15 support. NbF5 was tested as catalyst in both the preparations.Structural characterization by X Ray Diffraction and Transmission Electron Microscopy allowed evaluating the successful synthesis of SBA15 matrix, the microstructural features of ball milled and nanoconfined hydrides as well as the success of infiltration process. The evaluation of the sorption properties, by manometric Sievert-type apparatus and thermal desorption spectroscopy, revealed the efficiency of the hydride destabilization, obtained by the different routes, in decreasing the hydrogen release temperature and improving desorption kinetics.

► Nanoconfinement of 2NaBH4 + MgH2 into SBA-15 silica was successful in improving the thermodynamic and kinetic properties of the multi-component system
► The use of NbF5 as additive reduced the NaBH4 decomposition temperature and increased the desorption kinetics.
► Destabilization of hydrides can be gained by synergic effect of nanoconfinement and use of additive materials.