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

Abstract

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 àunder a hydrogen pressure of 2 MPa and desorb 6.5 wt.-% hydrogen within 10 min at 300 àunder 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.