LAUSR

Abstract In the present study, the NiS2 was synthesized by a one-step hydrothermal method. Then the MgH2-x wt% NiS2 (x = 0, 0.5, 1, 3, 5, 10) composites were prepared by mechanical ball-milling and their hydrogen storage properties were studied. Results indicate that the doped NiS2 changes into MgS and Mg2NiH4 during the heating process. Increasing NiS2 content significantly improves the hydrogenation and dehydrogenation kinetics of the composites. The onset dehydrogenation temperature is observed to shift downward from 330 °C for the ball-milled MgH2 to 210 °C for the MgH2-10 wt% NiS2 composite. Also, the MgH2-5 wt% NiS2 sample can absorb more than 5.1 wt% H2 within 1 h at 100 °C, while the ball-milled MgH2 can hardly absorb H2 at the same temperature. The enhanced hydrogen sorption kinetics is mainly attributed to the catalytic effect of in-situ formed MgS and Mg2NiH4 phases. In addition, the composites exhibit good cyclic performance, and the phase composition, microstructure, and reversible hydrogen storage capacity have almost no change during hydrogenation cycles.