Fe3O4 nanoclusters highly dispersed on a porous graphene support as an additive for improving the hydrogen storage properties of LiBH4.

Abstract

Fe3O4 nanoclusters anchored on porous reduced graphene oxide (Fe3O4@rGO) have been synthesized by a one-step hydrothermal route, and then ball milled with LiBH4 to prepare a hydrogen storage composite with a low onset dehydrogenation temperature, and improved dehydrogenation kinetics and rehydrogenation reversibility. The LiBH4–20 wt% Fe3O4@rGO composite begins to release hydrogen at 74 °C, which is 250 °C lower than for ball-milled pure LiBH4. Moreover, the composite can release 3.36 wt% hydrogen at 400 °C within 1000 s, which is 2.52 times as high as that of pure LiBH4. Importantly, it can uptake 5.74 wt% hydrogen at 400 °C under 5 MPa H2, and its hydrogen absorption capacity still reaches 3.73 wt% after 5 de/rehydrogenation cycles. The activation energy (Ea) of the hydrogen desorption of the composite is decreased by 79.78 kJ mol−1 when 20 wt% Fe3O4@rGO is introduced into LiBH4 as a destabilizer and catalyst precursor, showing enhanced thermodynamic properties. It could be claimed that not only the destabilization of Fe3O4, but also the active Li3BO3 species formed in situ, as well as the wrapping effect of the graphene, synergistically improve the hydrogen storage properties of LiBH4. This work provides insight into developing non-noble metals supported on functional graphene as additives to improve the hydrogen storage properties of LiBH4.