Synthesis of highly stable Ni nanoparticles via electrostatic self‐assembly for enhanced hydrogen storage of MgH 2

Abstract 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/Al 2 O 3 /GN) was fabricated to promote the hydrogen storage performance of MgH 2 via the electrostatic effect of NiAl‐LDH/GN precursor with a co‐calcination reduction process. MgH 2 ‐5 wt% Ni/Al 2 O 3 /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/Al 2 O 3 /GN on the hydrogen storage performance of MgH 2 was also discussed through experiments and theoretical calculation, and the synergistic catalytic mechanism of Ni/Al 2 O 3 /GN was clearly elaborated. This work provides a unique perspective for the preparation of highly stable and highly dispersible catalysts.