Comprehensive Study of Melt Infiltration for the Synthesis of NaAlH4/C Nanocomposites

摘要

In the search for suitable solid state hydrogen storage systems, NaAlH4 (7.4 wt H2) holds great promise due to its suitable thermodynamical properties. However, hydrogen release and uptake are hampered by high activation energies, most likely due to solid state mass transfer limitations. A recent strategy to improve the hydrogen de- and rehydrogenation properties of NaAlH4 is to reduce the particle size to the nanometer scale. We prepared high loadings of nanosized NaAlH4 confined in the pores of a carbon support by melt infiltration. XRD, nitrogen physisorption, high pressure DSC and solid-state NMR are used to evidence that the molten NaAlH4 infiltrates the carbon support, and forms a nanosized NaAlH4 phase lacking long-range order. The confined NaAlH4 shows enhanced hydrogen dehydrogenation properties and rehydrogenation under mild conditions that is attributed to the nanosize and close contact to the carbon matrix.