Improving hydrogen sorption performances of MgH2 through nanoconfinement in a mesoporous CoS nano-boxes scaffold

Abstract For the first time, structure-modified CoS-nanoboxes (CoS-NBs) scaffold as a multifunctional Supporting material has been developed by using a template-consumption method for nanoconfinement of MgH2 particles within its mesoporous structure (denoted as MgH2@CoS-NBs). Microstructural observations via transmission electron microscopy (TEM) reveal the uniform distribution of MgH2 nanocrystals within the mesoporous networks of CoS-NBs scaffold and the surface decoration of MgH2 crystals by in-situ formed MgS phase. The peculiar core-shell structured morphology of MgH2 nanocrystals and the “nano-size effect” notably enhances the thermodynamic properties of MgH2 through the reduction in hydriding and dehydriding enthalpies (−65.6 ± 1.1 and 68.1 ± 1.4 kJ mol−1 H2, respectively). Moreover, the improved hydrogen sorption kinetics can be attributed to the catalytic effect of MgS through reducing the intrinsic kinetic energy barriers for both hydriding and dehydriding (57.4 ± 2.2 and 120.8 ± 3.2 kJ mol−1 H2, respectively). The “nano-size effect” of nanoconfined Mg/MgH2 crystals, the catalyzing effect of MgS and the multifunctional role of CoS-NBs scaffold are likely to be synergistically contributed to the superior hydrogen sorption performances of MgH2@CoS-NBs composite, as compared to the pure MgH2.