Superior hydrogen performance of in situ formed carbon modified MgH2 composites

The MgH2-carbonic combustion product of the anthracene (CCPA) composite was synthesized by hydrogen combustion and mechanically ball-milled method to simultaneously achieve confinement by the in situ formed amorphous carbon. The amorphous carbon derived from the carbonic combustion product of anthracene in the MgH2-CCPA composite led to a significant increase in hydrogen sorption characteristics. The onset dehydrogenation temperature for the MgH2-CCPA composite was reduced to 589 K, which was 54 K less than that of pure milled MgH2. Regarding dehydrogenation kinetics, the MgH2-CCPA composite could release 5.933 wt% H-2 within 3000 s at 623 K, while only 3.970 wt% H-2 was liberated from the as-milled MgH2 within 3000 s at the same temperature. The MgH2-CCPA composite also exhibited excellent hydrogenation characteristics, absorbing 3.246 wt% of hydrogen within 3000 s at 423 K, which was three times higher than 0.818 wt% uptaken by the pure MgH2. The apparent activation energy (E-a) for the dehydrogenation of the MgH2-CCPA composite was significantly reduced from 161.1 kJ mol(-1) to 77.5 kJ mol(-1). The notable improvement in sorption kinetics of the MgH2-CCPA nanocomposite is ascribed to the in situ formed amorphous carbon during the hydrogenation/dehydrogenation process.

Automated summary

The MgH2-CCPA composite, synthesized through hydrogen combustion and mechanically ball-milled method, exhibited improved hydrogen sorption characteristics due to the in situ formed amorphous carbon. The dehydrogenation temperature and kinetics of the composite were significantly enhanced compared to pure milled MgH2, with higher hydrogen liberation and absorption capacities. The presence of amorphous carbon in the MgH2-CCPA composite contributed to the notable improvement in sorption kinetics.