A Tailored Ti-Based Rutile-Type High-Entropy Oxide: Unlocking Ultrafast De/Hydrogenation Kinetics of MgH2 via Multimetallic Synergism

Magnesium hydride (MgH 2 ) is widely regarded as a highly promising solid-state hydrogen storage material. However, its practical application is severely constrained by high operating temperatures and sluggish hydrogen absorption/desorption kinetics arising from multistep reaction energy barriers. Here, we rationally tailor a quinary Ti-based rutile-type high-entropy oxide to overcome these intrinsic limitations for the first time. The onset dehydrogenation temperature of the hybrid reduces to 195°C, which is 163°C lower than that of pristine MgH 2 . The composite releases 5.88 wt.% H 2 within 10 min at 250°C, accompanied by a 58% reduction in the apparent dehydrogenation activation energy. Moreover, a 1.84 wt.% H 2 uptake can be achieved within only 20 s at room temperature. The coexistence of various multivalent metal cations, lattice distortions, abundant defects, and oxygen vacancies in (TiNbCrTaFe)O 2 substantially reduces the multi-step reaction energy barriers during MgH 2 de/hydrogenation, enabling the overall kinetics to surpass those of all previously reported high-entropy catalyst-modified MgH 2 systems. This work expands the compositional design space and application scope of high-entropy oxides and provides a viable strategy for advanced hydrogen storage and catalytic systems.