A Single-Atom Interface Engineering Strategy to Promote Hydrogen Sorption Performances of Magnesium Hydride

Magnesium hydride (MgH 2 ) is regarded as a promising hydrogen storage material owing to its high gravimetric and volumetric capacity and low cost. However, its large-scale application is hampered by high stability leading to elevated temperature and slow kinetics for ab/desorption. To address these problems, herein, a composite having MgH 2 nanoconfined in a 3D nickel single atoms doped porous carbon (MgH 2 @3D Ni SA-pC) is successfully prepared. Benefitting from the nondestructive synthetic method, strong coupling between MgH 2 and 3D Ni SA-pC is achieved, and the composite exhibits superior hydrogen sorption performances as compared to blank MgH 2 . An onset desorption temperature down to 170 °C and the complete dehydrogenation at 250 °C within 60 min are observed. In particular, thermodynamics of MgH 2 is improved (ΔH ab = 67.9 kJ mol −1 H 2 ) and the heterogenous interfaces are stable during cycling without the formation of an intermetallic Mg 2 Ni catalytic phase. Experimental characterizations and theoretical calculations show that the robust interfaces induce charge transfer from Mg/MgH 2 to Ni SA-pC, which contributes to the weakened Mg─H bonds and thereby improves kinetic and even thermodynamics. Such an interface engineering strategy using single-atom Ni catalyst to simultaneously nano-confine and catalyze MgH 2 paves a way to the design of high-performance hydrogen storage materials.