Rapid Hydrolysis of Submicron Magnesium Catalyzed by In Situ-Generated Multi-Nickel Alloys

The hydrolysis of lightweight metal-based materials is a promising technology for supplying hydrogen to portable fuel cells. Various additives for the catalytic modification of Mg hydrolysis have been investigated. Efficient catalysts and small magnesium particle sizes are key to enhancing the rate of hydrogen production. In this study, submicron Mg and in situ-generated multi-Ni alloy catalysts (NiM@Gn) are prepared and composited for the first time. Among the composites prepared, Mg-5 wt.%NiM@Gn exhibits the best hydrolysis performance. This composite can release 804.4 mL g^-1 hydrogen within 30 s (98.32% of the total yield), and its initial hydrogen release rate is as high as 5480 mL g^-1 min^-1, with a low apparent activation energy of hydrolysis of 10.85 kJ mol^-1. Submicron Mg greatly improves the rate of the hydrolysis reaction, and graphene facilitates the exfoliation of agglomerated Mg particles in water. Mg₂Ni and (Fe, Ni) alloys generate microgalvanic cells with Mg in situ, significantly enhancing the electrochemical corrosion efficiency of Mg. Theoretical calculations show that these alloys accelerate electron transfer and coupling on the Mg surface. This study guides for the design and preparation of multi-catalysts and establishes the feasibility of submicron Mg for hydrogen generation through hydrolysis.