Catalytic De/Hydrogenation in Mg by Co-Doped Ni and VOx on Active Carbon: Extremely Fast Kinetics at Low Temperatures and High Hydrogen Capacity

A multi‐component catalyst Ni‐VOx/AC (VOx is comprised of V2O5 and VO2, x = 2.18) was synthesized by a wet impregnation method. The synthesized Ni‐VOx/AC shows a superior catalytic effect on de/hydrogenation of Mg. The MgH2+Ni‐VOx/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 (Ea) indicates that Ni‐VOx/AC catalyst is highly efficient for Mg de/hydrogenation, which may be ascribed to the synergistic effect of bimetals (metal oxides) and nanocarbon. A novel multi‐component catalyst Ni‐VOx/AC is synthesized and exhibits superior hydrogen storage properties when milled with Mg. The images shows a comparison of the capacity and average kinetics in 1 min of hydrogenation for Mg‐based nanocomposites at 150 °C (left blue axes) and of 10 min of dehydrogenation at 300 °C (right green axes). This highlights the enhanced hydrogen storage property, which is ascribed to different catalytic roles of Ni, VOx and AC in nano‐Ni‐VOx/AC catalyst doping.