MgCl 2 promoted hydrolysis of MgH 2 nanoparticles for highly efficient H 2 generation

The hydrolysis reaction of many hydrides delivers very high hydrogen capacity and is very attractive for onsite hydrogen generation. However, in real application, large excess of water is required to ensure complete hydrolysis, which causes significant capacity loss. Hydrolysis of MgH2 gives insoluble Mg(OH)2, which allows easy separation and repeated using of the excessive water. This will minimize the capacity loss caused by the excessive water. The low solubility of Mg(OH)2, however, usually causes incomplete utilization of MgH2. In this paper, we solve this paradox by using MgH2 nanoparticles together with the promotion effect of MgCl2 solution. Complete and efficient hydrogen generation can be achieved despite of the Mg(OH)2 formation. We show that by recycling the MgCl2 solution, this reaction system can approach the theoretical hydrogen capacity of 6.5wt%, providing a promising solution for onsite hydrogen generation.