They published their work on Dec. 20 in Energy Material Advances.
"Economic, efficient, and safe hydrogen storage methods play a crucial role in exploiting hydrogen energy, reducing carbon emissions, and improving the utilization efficiency of renewable clean energies," said paper author Jianxin Zou, professor in National Engineering Research Center of Light Alloys Net Forming & State Key Laboratory of Metal Matrix Composites. "Solid-state hydrogen storage in hydrides has been considered as a promising hydrogen storage technology. Although the industrial application of solid-state hydrogen storage technologies with metal hydride is still in the stage of an attack."
"Take Magnesium-based hydrides as an example, Magnesium is the eighth most abundant element in Earth's crust, and low-cost, with excellent operation safety and environmentally friendly," Zou said. "Magnesium-based hydrides are attractive candidates for large-scale hydrogen energy storage systems due to their high hydrogen storage densities, good cyclic performance, and high abundance of Mg on earth."
"The implementation of MgH2 as a hydrogen-storage medium has long been restricted by two dominating intrinsic challenges."
Zou explained that the first obstacle is the high thermodynamic stability (ΔH = 74.7 kJ mol−1 H2) resulting in the high decomposition temperature of MgH2. Another obstacle is the rather sluggish hydrogen ab/de-sorption kinetics originating from high H2 dissociation energy barrier, slow hydrogen diffusion rate in MgH2 bulk.
To improve hydrogen storage performance of MgH2/Mg, many efforts have been made, such as catalyst doping, nano-crystallization, alloying, destabilization. And achieving dual regulation of the kinetics and thermodynamics of MgH2 is essential for the practical applications. Previous works proved that introducing catalysts into Mg/MgH2 could accelerate the hydrogen de-/absorption kinetics obviously. Among all the catalytic compounds, MXenes-based catalysts have attracted significant attention owing to the unique two-dimensional structure and the component tunability of MXenes. However, similar to common catalysts, most MXenes-based catalysts, such as Ti3C2
