Rapid hydrogen energy storage of self-supporting VS2/NC modified MgH2

Magnesium metal and its hydride have the characteristics of high hydrogen storage capacity, which is suitable for storing hydrogen energy. In this paper, VS 2 /NC catalyst supported on nanosheet carbon was synthesized by hydrothermal method with organic matter as raw material, then the MgH 2 + x wt.% VS 2 /NC ( x = 0, 3, 6, 9) composites were prepared by ball milling with MgH 2 . The phase characterization of the composite material showed that the VS 2 and MgH 2 phases in the composite material remain stable during ball milling and subsequently, the hydrogen absorption/desorption cycle. There were V 4+ and V 2+ ions (an atomic ratio of 3.77:1) in the catalyst. At 593 K, the capacities of the composites were 5.71, 6.11, 5.62, and 5.33 wt.% H 2 , respectively. The time to reach the maximum hydrogen desorption capacity of 95% was 190, 30, 20, and 23 min, respectively. The dehydrogenation activation energy of the material with x = 6 is reduced by nearly 50 kJ/mol H 2 . The initial dehydrogenation temperature of the material decreases to 323 K. Because of the valence state transition between V ions, the band gap of the composite material is narrowed, which significantly improves the hydrogen absorption and desorption reaction kinetics.