Nonisothermal and Isothermal Hydrogen Storage Behaviors of MgH2‐Based Composites Catalyzed by Carbon Isomeric Catalysts: Lightweight and Efficient Catalysis to Achieve High Capacity of Hydrogen Storage

MgH 2 ‐based composites are prepared by high‐energy ball milling surface catalysis with carbon isomeric catalysts to explore isothermal and nonisothermal H 2 storage behavior. The reduction particle size and catalysts are conducive to absorption/desorption. The release peak temperatures of MgH 2 catalyzed by activated carbon ( AC), carbon nanotubes ( CNTs), reduced graphene oxide ( rGO), and expanded graphite (EG) are 445, 424, 458, and 446 °C, lower than that of MgH 2 (≈463 °C). The hydrogenation capacities for the 3rd cycle of MgH 2 , MgH 2 –AC, MgH 2 –CNTs, and MgH 2 –EG are 3.35, 6.52, 6.66, and 6.92 wt%, corresponding to 47%, 90%, 92%, and 96% conversion rates. The dehydrogenation capacities increase to 5.86, 4.94, 3.18, and 5.74 wt% of MgH 2 –AC, MgH 2 –CNTs, MgH 2 –rGO, and MgH 2 –EG within 0.5 h, higher than MgH 2 (2.29 wt%). The final dehydrogenation capacities of MgH 2 , MgH 2 –AC, MgH 2 –CNTs, MgH 2 –rGO, and MgH 2 –EG are 2.84, 6.69, 5.14, 3.65, and 6.61 wt%. The absorption capacities of MgH 2 , MgH 2 –AC, MgH 2 –CNTs, MgH 2 –rGO, and MgH 2 –EG within 0.5 h are 2.42, 6.47, 6.21, 3.03, and 4.20 wt%, and the final hydrogenation capacities reach 2.58, 6.65, 6.33, 3.10, and 4.34 wt%. The initial kinetics and the final degrees of absorption/desorption of MgH 2 are elevated by carbon isomeric catalysts.