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

Magnesium hydride (MgH2) 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 MgH2 nanoconfined in a 3D nickel single atoms doped porous carbon (MgH2@3D Ni SA-pC) is successfully prepared. Benefitting from the nondestructive synthetic method, strong coupling between MgH2 and 3D Ni SA-pC is achieved, and the composite exhibits superior hydrogen sorption performances as compared to blank MgH2. An onset desorption temperature down to 170 degrees C and the complete dehydrogenation at 250 degrees C within 60 min are observed. In particular, thermodynamics of MgH2 is improved (Delta Hab = 67.9 kJ mol-1 H2) and the heterogenous interfaces are stable during cycling without the formation of an intermetallic Mg2Ni catalytic phase. Experimental characterizations and theoretical calculations show that the robust interfaces induce charge transfer from Mg/MgH2 to Ni SA-pC, which contributes to the weakened Mg & horbar;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 MgH2 paves a way to the design of high-performance hydrogen storage materials.