Enhanced hydrogen generation via hydrolysis of Mg–Mg₂NiH₄ system

Producing hydrogen via hydrolysis of light weighted metal-based materials is a promising technology for exploiting portable hydrogen–air fuel cells. Various additives have been designed to catalyze the hydrolysis behavior of Mg-based materials. In most cases, however, the kinetic promotion is in the expense of the systematic hydrogen generation yield. In this work, Mg–Mg₂NiH₄ system with extraordinary hydrolysis property is explored for hydrogen generation in 3.5% NaCl aqueous solution for the first time. The Mg-10 wt% Mg₂NiH₄ composite releases 845.1 mL g⁻¹ (yield of 94.7%) hydrogen in just 20 s, with a maximum hydrogen generation rate (mHGR) of 6391 mL g⁻¹ min⁻¹. Our results have experimentally shown the synergistic effect between Mg and Mg₂NiH₄ on hydrolysis reaction. The in-situ ultrafine Ni particles derived from the rapid hydrolysis of Mg₂NiH₄ form a large amount of micro-galvanic cells with Mg, accelerating the electrochemical corrosion of Mg efficiently. In turn, the hydrolysis reaction of Mg₂NiH₄ can be dramatically driven by the local solution heat due to the violent exothermic reaction of Mg. The cooperative effect provides fresh strategy designing high-property hydrolysis materials with no substantial loss of the hydrogen supply capacity.