Ultrafast Hydrogen Production via Hydrolysis of MgH2-NaH Composite

Abstract

Magnesium hydride (MgH2) has attracted considerable interest due to a number of favourable characteristics for hydrogen production via hydrolysis. In this study, MgH2-NaH composites with varying composition ratios were prepared by ball milling for different durations. The hydrogen production performances and enhancement mechanisms were subjected to meticulous investigation. The results revealed that the hydrogen production rate and kinetic properties of the composites were significantly improved with the rise in NaH content. For the MgH2-10 wt% NaH composites, the hydrogen production rate exhibited an initial increase followed by a subsequent decrease with the prolongation of ball milling. It is noteworthy that the hydrolysis of the composites in deionised water exhibited a significant improvement in reaction kinetics even after a mere 1 h of ball milling, releasing 1119 mL g−1 of hydrogen in 30 s, with a conversion rate of 69.2%. The highest hydrolysis hydrogen generation rate of the 10 h milled MgH2-10 wt% NaH composite in deionised water at 30 °C was 1360 mL g−1, with a hydrogen conversion rate of 83.7% and a hydrolysis activation energy of 17.79 kJ mol−1. The notable improvement in the hydrolysis performance of the MgH2-NaH composite is attributed to the rapid generation of high temperatures at the interface, resulting from the exothermic reaction of sodium hydride hydrolysis.