ZrO 2 Clusters Enabling Room‐Temperature Hydrogen Absorption and Low‐Temperature Desorption of Commercial Mg Powder for Reversible Hydrogen Storage

Magnesium‐based hydrogen storage materials exhibit great application potential, but high operating temperature and slow kinetics hinder their large‐scale utilization. Here, the amorphous‐carbon‐stabilized Mg particles decorated with sub‐2 nm ZrO 2 nanoclusters are reported, which were in situ fabricated via ball milling of commercial Mg powder, acetone (ACE), and zirconium acetylacetonate (Zr(acac) 4 ). The optimized Mg‐ACE‐1 wt.% Zr composite achieves rapid hydrogen absorption of 4.25 wt.% at 30°C within 60 min and exhibits high cycling stability with nearly no H 2 capacity fading after 40 cycles at 300°C under 30 bar H 2 . Notably, the Mg‐ACE‐1 wt.% Zr sample enables reversible hydrogenation at room temperature and dehydrogenation at high temperature, achieving better energy efficiency than conventional thermally driven MgH 2 and showing promise for coupling with renewable hydrogen production. Interfacial characterizations and DFT calculations confirm that the in situ formed ZrO 2 /Mg interface accelerates H 2 adsorption, dissociation, and diffusion.