Room-Temperature Transient Hydrogen Uptake of MgH2 Induced by Nb-Doped TiO2 Solid-Solution Catalysts

The practical applications of MgH2 as a high-densityhydrogen carrier depend heavily on efficient and low-cost catalyststo accelerate the dehydriding/hydriding reactions at moderate temperatures.In the present work, this issue is addressed by synthesizing Nb-dopedTiO(2) solid-solution-type catalysts that dramatically improvethe hydrogen sorption performances of MgH2. The catalyzedMgH(2) can absorb 5 wt % of H-2 even at room temperaturefor 20 s, release 6 wt % of H-2 at 225 degrees C within 12min, and the complete dehydrogenation can be achieved at 150 degrees Cunder a dynamic vacuum atmosphere. Density functional theory calculationsreveal that Nb doping introduces Nb 4d orbitals with stronger interactionwith H 1s into the density of states of TiO2. This considerablyenhances both the adsorption and dissociation ability of the H-2 molecule on the catalysts surface and the hydrogen diffusionacross the specific Mg/Ti(Nb)O-2 interface. The successfulimplementation of solid solution-type catalysts in MgH2 offers a demonstration and inspiration for the development of high-performancecatalysts and solid-state hydrogen storage materials.