One of the most technically challenging barriers to the
widespread commercialization of hydrogen-fueled
devices and vehicles remains hydrogen storage. More environmentally
friendly and effective nonmetal catalysts are required to improve
hydrogen sorption. In this paper, through a combination of experiment
and theory, we evaluate and explore the catalytic effects of layered
graphene nanofibers toward hydrogen release of light metal hydrides
such as sodium alanate. Graphene nanofibers, especially the helical
kind, are found to considerably improve hydrogen release from NaAlH4, which is of significance for the further enhancement of
this practical material for environmentally friendly and effective
hydrogen storage applications. Using density functional theory, we
find that carbon sheet edges, regardless of whether they are of zigzag
or armchair type, can weaken Al–H bonds in sodium alanate,
which is believed to be due to a combination of NaAlH4 destabilization
and dissociation product stabilization. The helical form of graphene
nanofibers, with larger surface area and curved configuration, appears
to benefit the functionalization of carbon sheet edges. We believe
that our combined experimental and theoretical study will stimulate
more explorations of other microporous or mesoporous nanomaterials
with an abundance of exposed carbon edges in the application of practical
complex light metal hydride systems.