In Situ AlNi Derived from Ni/Dual‐Phase TiO ₂ for Hydrogen Storage Enhancement of MgH ₂

ABSTRACT Though recognized as a highly promising solid‐state hydrogen storage material, magnesium hydride (MgH ₂ ) in application is hindered by sluggish kinetics and high operating temperatures. Alloying and catalyzing are proven effective to enhance the hydrogen storage performance of MgH ₂ . Herein, the dual‐phase TiO ₂ (anatase/rutile TiO ₂ ) supported Ni nanoparticle (Ni/Dp‐TiO ₂ ) were fabricated and incorporated into Mg ₉₀ Al ₁₀ . Mg ₉₀ Al ₁₀ ‐10 wt.% Ni/Dp‐TiO ₂ can absorb 4.28 wt.% H ₂ at 150°C and desorb 3.86 wt.% H ₂ at 250°C within 2500 s, outperforming Mg ₉₀ Al ₁₀ , which achieves 0.96 wt.% H ₂ absorption and 0.27 wt.% H ₂ desorption under identical conditions. Notably, the dehydrogenation activation energy ( E _a ) of Mg ₉₀ Al ₁₀ ‐10 wt.% Ni/Dp‐TiO ₂ is dramatically reduced to 56.36 kJ mol ⁻¹ , accompanied by significant decreases in the hydrogenation and dehydrogenation enthalpies ( ΔH _abs and ΔH _des ) 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 Mg ₉₀ Al ₁₀ ‐10 wt.% Ni/Dp‐TiO ₂ originates from the electron‐mediating effect of the in situ formed AlNi/Dp‐TiO ₂ and of Al species (including Mg‐Al solid solution, Mg ₁₇ Al ₁₂ , and Mg ₂ Al ₃ ). This work provides a viable strategy for the rational design of highly efficient catalysts toward advanced MgH ₂ ‐based hydrogen storage systems.