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 (E_a) 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.