Synthesis of highly stable Ni nanoparticles via electrostatic self-assembly for enhanced hydrogen storage of MgH₂

Magnesium-based hydrides have been widely recognized as an appropriate choice for solid-state hydrogen storage. However, its undesirable thermodynamics and sluggish hydrogenation/dehydrogenation kinetics are major bottlenecks for its application. Herein, a highly stable and highly dispersed Ni-based catalyst (Ni/Al₂O₃/GN) was fabricated to promote the hydrogen storage performance of MgH₂ via the electrostatic effect of NiAl-LDH/GN precursor with a co-calcination reduction process. MgH₂-5 wt% Ni/Al₂O₃/GN exhibits excellent hydrogen storage performance, releasing about 5.7 wt% hydrogen in 3500 s at 250 °C, and can reach a saturation hydrogen absorption of about 6.15 wt% in 3000 s at 100 °C. Furthermore, it also shows low dehydrogenation apparent activation energy of 89.1 and 118.2 kJ·mol⁻¹. Impressively, the catalyst ensures the stability of both the physical phase and structure during ball milling and cycling process. The role of each phase in Ni/Al₂O₃/GN on the hydrogen storage performance of MgH₂ was also discussed through experiments and theoretical calculation, and the synergistic catalytic mechanism of Ni/Al₂O₃/GN was clearly elaborated. This work provides a unique perspective for the preparation of highly stable and highly dispersible catalysts.