Nano-synergy enables highly reversible storage of 9.2 wt% hydrogen at mild conditions with lithium borohydride

Abstract

In this work, we report an effective synthetic strategy to obtain LiBH 4 featuring low-temperature and highly reversible hydrogen cycling. This is achieved by a unique nanocomposite structure where LiBH 4 nanoparticles of 5–10 nm on graphene are decorated by Ni nanocrystals of 2–4 nm. The prepared LiBH 4 nanocomposite reversibly desorbs and absorbs ~9.2 wt% hydrogen at 300 °C with a stable cyclability for up to 100 cycles, superior to all the literature results reported so far. The decisive factor affecting the hydrogen cycling is the reactivity of boron toward hydrogen. The formation of stable B 12 H 12 2- cluster during hydrogen cycling has been successfully prevented. The synergetic effects of nanostructuring and nanocatalysis lead to efficient formation of BH 4 ¯ during hydrogenation and elemental boron during dehydrogenation. This breakthrough sheds light on new strategies to explore borohydride family for practical hydrogen storage applications. A unique nanocomposite of Ni nanocrystal-decorated LiBH 4 nanoparticles smaller than 10 nm anchored on graphene delivers a reversible hydrogen storage capacity of 9.2 wt% at 300 °C with a stable cyclability for 100 cycles. ● A novel one-pot solvothermal process is proposed for the fabrication of LiBH 4 nanostructures. ● 5–10 nm LiBH 4 nanoparticles decorated by Ni nanocrystals on graphene are successfully synthesized. ● The LiBH 4 nanocomposite stores reversibly 9.2 wt% H 2 at 300 °C and 100 bar H 2 . ● Formation of volatile B 2 H 6 and stable Li 2 B 12 H 12 during hydrogen cycling is prevented.