Catalytic de/hydrogenation in Mg by co-doped Ni and VO _x on active carbon: Extremely fast kinetics at low temperatures and high hydrogen capacity

A multi-component catalyst Ni-VO _x/AC (VO _x is comprised of V ₂ O ₅ and VO ₂, x = 2.18) was synthesized by a wet impregnation method. The synthesized Ni-VO _x/AC shows a superior catalytic effect on de/hydrogenation of Mg. The MgH ₂ + Ni-VO _x/AC composites can absorb 6.2 wt.-% hydrogen within only 1 min at 150 °C under a hydrogen pressure of 2 MPa and desorb 6.5 wt.-% hydrogen within 10 min at 300 °C under an initial hydrogen pressure of 1 KPa, which overcomes a critical barrier for practical use of Mg as a hydrogen storage material. A significant decrease of activation energy (E _a) indicates that Ni-VO _x/AC catalyst is highly efficient for Mg de/hydrogenation, which may be ascribed to the synergistic effect of bimetals (metal oxides) and nanocarbon.