Though recognized as a highly promising solid-state hydrogen storage material, magnesium hydride (MgH2) in application is hindered by sluggish kinetics and high operating temperatures. Alloying and catalyzing are proven effective to enhance the hydrogen storage performance of MgH2. Herein, the dual-phase TiO2 (anatase/rutile TiO2) supported Ni nanoparticle (Ni/Dp-TiO2) were fabricated and incorporated into Mg90Al10. Mg90Al10-10 wt.% Ni/Dp-TiO2 can absorb 4.28 wt.% H2 at 150°C and desorb 3.86 wt.% H2 at 250°C within 2500 s, outperforming Mg90Al10, which achieves 0.96 wt.% H2 absorption and 0.27 wt.% H2 desorption under identical conditions. Notably, the dehydrogenation activation energy (Ea) of Mg90Al10-10 wt.% Ni/Dp-TiO2 is dramatically reduced to 56.36 kJ mol-1, accompanied by significant decreases in the hydrogenation and dehydrogenation enthalpies (ΔHabs and ΔHdes) to -66.25 and 68.18 kJ mol-1, respectively. Both Density Functional Theory (DFT) calculations and experimental results demonstrate that the simultaneous enhancement of the kinetics and thermodynamics of Mg90Al10-10 wt.% Ni/Dp-TiO2 originates from the electron-mediating effect of the in situ formed AlNi/Dp-TiO2 and of Al species (including Mg-Al solid solution, Mg17Al12, and Mg2Al3). This work provides a viable strategy for the rational design of highly efficient catalysts toward advanced MgH2-based hydrogen storage systems.
Li et al. (Wed,) studied this question.