High-loading LiBH4 Confined in Structurally Tunable Ni Catalyst-decorated Porous Carbon Scaffold for Fast Hydrogen Desorption

Catalysts combined with nanoconfinement can improve the sluggish desorption kinetics and poor reversibility of LiBH4. However, at high LiBH4 loading, their hydrogen storage performance is significantly reduced. Herein, a porous carbon-sphere scaffold decorated with Ni nanoparticles (NPs) was synthesised by calcining a Ni metal-organic framework precursor, followed by partial etching of the Ni NPs to fabricate an optimised scaffold with a high surface area and large porosity that accommodates high LiBH4 loading (up to 60 wt.%) and exhibits remarkable catalyst/nanoconfinement synergy. Owing to the catalytic effect of Ni2B (formed in situ during dehydrogenation) and the reduced hydrogen diffusion distances, the 60 wt.% LiBH4 confined system exhibited enhanced dehydrogenation kinetics with >87% of the total hydrogen storage capacity released within 30 min at 375 degrees C. The apparent activation energies were significantly reduced to 110.5 and 98.3 kJ/mol, compared to that of pure LiBH4 (149.6 kJ/mol). Moreover, partial reversibility was achieved under moderate conditions (75 bar H-2, 300 degrees C) with rapid dehydrogenation during cycling.