Improved hydrogen storage properties of MgH2 using transition metal sulfides as catalyst

Abstract

In this study, some transition metal sulfides (TiS2, NbS2, MoS2, MnS, CoS2 and CuS) are used as catalyst to enhance the hydrogen storage behaviors of MgH2. The MgH2-sulfide composites with different sulfides addition are prepared by ball-milling. The phase composition and hydrogen storage properties are studied in detail. The results confirm that all these sulfides can significantly increase the hydrogen desorption and absorption kinetics of MgH2. The MgH2–TiS2 has the best hydrogenation and dehydrogenation kinetics, followed by the MgH2–NbS2, MgH2–MnS, MgH2–MoS2, MgH2–CoS2, MgH2–CuS and MgH2. Also, the onset dehydrogenation temperature of the MgH2–TiS2 is about 204 °C, which is lower about 126 °C than that of the MgH2. The dehydrogenation activation energy can be reduced to 50.8 kJ mol−1 when doping TiS2 in MgH2. The beneficial catalytic effects of the sulfides can be ascribed to the in-situ formation of MgS, TiH2, NbH, Mo, Mn, Mg2CoH5 and MgCu2 phases.