Catalytic effect of double transition metal sulfide NiCo2S4 on hydrogen storage properties of MgH2

The limited practicality of magnesium hydride (MgH2) is due to its remarkable thermodynamic steadiness and sluggish hydrogen (H2) storage rate. In this study, NiCo2S4, a double transition metal sulfide, was synthesized and used to promote the kinetic properties of MgH2. Starting release temperature of MgH2- 10 NiCo2S4 composite is 203 °C. MgH2-10 NiCo2S4 composite releases 6.11 wt% H2 in 5 min at 325 °C, and absorbs 5.54 wt% H2 in 1 min at 150 °C. Besides, the Arrhenius equation yields the activation energy (Ea) of MgH2-10 NiCo2S4 composite to be 86.50 ± 2.00 kJ/mol. It is noteworthy that the MgH2-10 NiCo2S4 composite generated MgS, Mg2Ni and Mg2Co in situ active species during the first dehydrogenation process. The synergistic effect between the MgS, Mg2Ni/Mg2NiH4 and Mg2Co/Mg2CoH5 multiphase catalytic systems was generated in the cycle, which observably boosted the kinetics of Mg/MgH2.