A mechanical-force-driven physical vapour deposition approach to fabricating complex hydride nanostructures

Nanoscale hydrides desorb and absorb hydrogen at faster rates and lower temperatures than bulk hydrides because of their high surface areas, abundant grain boundaries and short diffusion distances. No current methods exist for the direct fabrication of nanoscale complex hydrides (for example, alanates, borohydrides) with unique morphologies because of their extremely high reducibility, relatively low thermodynamic stability and complicated elemental composition. Here, we demonstrate a mechanical-force-driven physical vapour deposition procedure for preparing nanoscale complex hydrides without scaffolds or supports. Magnesium alanate nanorods measuring 20–40 nm in diameter and lithium borohydride nanobelts measuring 10–40 nm in width are successfully synthesised on the basis of the one-dimensional structure of the corresponding organic coordination polymers. The dehydrogenation kinetics of the magnesium alanate nanorods are improved, and the nanorod morphology persists through the dehydrogenation–hydrogenation process. Our findings may facilitate the fabrication of such hydrides with improved hydrogen storage properties for practical applications. Due to their high reactivity and relatively low thermodynamic stability, direct routes to nanoscale complex hydrides are highly difficult to achieve. Here the authors show a vapour deposition method driven by mechanical force, which allows the formation of complex metal nanorods for hydrogen storage.