Nano-inclusion in one step: spontaneous ice-templating of porous hierarchical nanocomposites for selective hydrogen release

Abstract

3-Dimensional porous scaffold materials can be fabricated by ice templating sheets of graphene oxide (GO) or partially reduced graphene oxide (rGO). Aqueous suspensions of GO (or rGO) can be cast into monoliths or formed as beads on cooling and the solid matrices then fashioned with either laminar or radial porosity as a result. Further, ammonia borane (AB) can be integrated into the hierarchical structures in situ in a one-step process without the requirement of melt infiltration or solution impregnation techniques. Compared to AB itself, the ensuing self-assembled beads release hydrogen at a reduced onset temperature and without volume expansion on heating, suppressing the release of diborane, borazine and ammonia. Pre-reduction of the GO matrix material (to rGO) eliminates CO/CO₂ release from the composites.