Hydrogen-induced magnesium-zirconium interfacial coupling: enabling fast hydrogen sorption at lower temperatures

The implementation of magnesium (Mg) as a hydrogen-storage medium has long been restricted because of its rather sluggish hydrogen sorption at high temperatures. Here, we report a method for using hydrogen-induced Mg-Zr interfacial coupling to manipulate the migration of hydrogen atoms and thus tune their uptake and release in a micrometer-sized Mg-rich composite. The associated Mg-Zr-H interfaces were assembled in situ by high-pressure ball milling and isothermal treatment of MgH 2 and Zr powders under a hydrogen atmosphere. The interfaces gradually disintegrated upon MgH 2 desorption but also recovered their original compositions upon absorption while the ZrH 2 originating from Zr hydrogenation remained completely unchanged. Compared to pure MgH 2 , the hydrogen sorption of the Mg-Zr-H composite was thus shown to be dramatically faster at lower temperatures, whereby it not only absorbed hydrogen close to saturation at 100 °C within 2 h, while the pure Mg did not absorb hydrogen at all, but also started to release hydrogen at ∼235 °C with a reduction in the activation energy of desorption by ∼40 kJ mol −1 . These remarkable enhancements cannot be explained by the decrease in the size of the MgH 2 grains alone but are most likely due to the introduction of Mg-Zr-H interfaces and large fractions of defects that provide channels for facile hydrogen dissociation and migration into the Mg/MgH 2 matrix. The construction of energy-favorable Mg-Zr-H interfaces provides channels to control hydrogen transfer to realize fast storage in Mg-based materials.