Facet‐Engineered Anatase TiO ₂ Nanoflowers with Anchored Single‐Atom Pd for Ultrafast Hydrogen Storage Kinetics

Abstract Securing a clean and sustainable energy future hinges on developing high‐performance hydrogen storage technologies. However, the widely practical application is hindered by slow kinetics and high thermodynamic stability. Herein, a facet‐engineered strategy is developed to modulate metal–support interactions by constructing marimo‐like anatase TiO ₂ nanoflowers enriched with {001} facets as scaffolds for Pd single atoms (PdSAs/A‐TiO ₂ ). Strong Pd–O bonding and nano‐confinement ensure atomic dispersion and electronic coupling. The MgH ₂ ‐PdSAs/A‐TiO ₂ composite exhibits ultrafast H ₂ release (6 wt.% in 3.5 min at 250°C) and absorption (1.2 wt.% in 5 min at 25°C). PdSAs‐induced electronic modulation shifts Ti 3d states toward the Fermi level, enhancing hydrogen activation and reducing the energy barrier of rate‐determining step (RDS) in Mg/MgH ₂ from 1.43 to 0.31 eV. A high capacity retention of 92.6% after 10 dehydrogenation/re‐hydrogenation cycles at 300°C is achieved by MgH ₂ ‐PdSAs/A‐TiO ₂ NFs, in sharp contrast to ball‐milled MgH ₂ (46.1%). In situ formation of a MgTi ₂ O ₄ interfacial phase replaces the inert MgO layer, providing a fast hydrogen transport network that facilitates H‐atom migration between PdSAs and the Mg matrix. This facet‐directed single‐atom and interfacial phase engineering concept offers a unified strategy to overcome thermodynamic and kinetic bottlenecks in MgH ₂ ‐based hydrogen storage.