Non-stoichiometric Ni3ZnC0.7 Carbide Loading on Melamine Sponge-Derived Carbon for Hydrogen Storage Performance Improvement of MgH2

The high operating temperatures and slow kinetics limit the application of MgH2-based hydrogen storage materials. Here, a composite of Ni3ZnC0.7/carbon nanotubes loaded onto a melamine sponge-derived carbon (MS) skeleton is prepared and loaded onto MgH2. During dehydrogenation, Ni3ZnC0.7 reacts with MgH2 and in situ changes to Mg2Ni/Zn. The transformation of Mg2Ni/Mg2NiH4 serves as a “hydrogen pump”, providing diffusion channels for hydrogen atoms and molecules to promote the de-/hydrogenation processes. Moreover, Zn/MgZn2 provides the catalytic sites for the transformation of Mg/MgH2. The length of the Mg–H bond is elongated from 1.72 to 1.995 Å, and the dissociation energy barrier of MgH2 is reduced from 1.55 to 0.49 eV. As a result, MgH2 with 2.5 wt