This paper reported the performance and mechanism of hydrogen generation via hydrolysis of ball-milled Mg-Mg₂Si composite (5.3 wt % Si-94.7 wt % Mg) in deionized water and in MgCl₂ solution. The results showed that the obtained Mg-Mg₂Si composite presented relatively higher hydrogen generation performance than pure magnesium. Adoption of 0.5 M MgCl₂ solution to replace deionized water sufficiently and vastly enhanced the hydrolysis properties of the Mg-Mg₂Si composite. The composite in 0.5 M MgCl₂ solution generated 445 mL/g hydrogen in 5 min, 688 mL/g hydrogen in 10 min and 889 mL/g hydrogen (conversion rate 99%) in 40 min at 328 K. This remarkable improvement is due to that the addition of Si element in the composite and the introduction of MgCl₂ in solution, as well as the special preparation process of the materials, could decrease the formation of continuous magnesium hydroxide passive layer on the particle surface, directly or indirectly. Moreover, the apparent activation energies for composite hydrolysis in deionized water, in 0.5 and 2.0 M MgCl₂ solution were calculated to be 30.1 ± 0.6, 9.5 ± 0.1 and 3.7 ± 0.2 kJ/mol, respectively. This work demonstrates that the hydrogen generation system based on low-cost and high-performance Mg-Mg₂Si composite is very applicable and promising; and it may open a new avenue for onsite hydrogen supply.

本文报道了在去离子水和MgCl ₂溶液中球磨Mg-Mg ₂ Si复合材料（5.3 wt％Si-94.7 wt％Mg）水解产生氢的性能和机理。结果表明，所获得的Mg-Mg ₂ Si复合材料具有比纯镁更高的产氢性能。采用0.5 M MgCl ₂溶液足以代替去离子水，并大大增强了Mg-Mg ₂ Si复合材料的水解性能。0.5 M MgCl _2中的复合物在328 K下，溶液在5分钟内产生445 mL / g氢，在10分钟内产生688 mL / g氢，在40分钟内产生889 mL / g氢（转化率99％）。在复合材料中加入MgCl _2和在溶液中引入MgCl ₂，以及材料的特殊制备工艺，都可以直接或间接减少在颗粒表面上形成连续的氢氧化镁钝化层。此外，在去离子水中，0.5 MgCl ₂和2.0 M MgCl ₂溶液中，复合水解的表观活化能分别计算为30.1±0.6、9.5±0.1和3.7±0.2 kJ / mol。这项工作证明了基于低成本高性能Mg-Mg ₂的制氢系统硅复合材料非常适用且很有前途；它将为现场氢气供应开辟一条新途径。