Structural and defect engineering of Pt-loaded MAX fibers with oxygen vacancies for enhanced hydrogen storage properties of MgH2

Magnesium hydride (MgH₂) is a promising solid-state hydrogen storage material due to its high hydrogen content and cyclic stability. However, its practical applications are limited by slow desorption kinetics and a high dehydrogenation temperature. To address these challenges, Pt-loaded MAX fibers with oxygen vacancies (Pt@MFs) have been synthesized by using vortex and hydrothermal methods. And the effects of the Pt@MFs on the hydrogen storage properties of MgH₂ are investigated. The results display that the MgH₂ doped with 10wt% Pt@MFs begins dehydrogenation at 169.3 °C and absorbs 5.73 wt% hydrogen in just 30 s at 125 °C and 30 bar hydrogen pressure. After 30 cycles, the MgH₂–10 wt% Pt@MFs retains 98.7% of its initial capacity, showcasing excellent cycling stability. The synergistic effect of the MAX fiber network's active sites, oxygen vacancies, anchored Pt nanoparticles and intermetallic compounds (PtTi, Pt₃Ti) in the MgH₂–10 wt% Pt@MFs composite significantly enhances hydrogen storage kinetics by facilitating diffusion, optimizing electron transfer, and weakening Mg-H bonds. The design concept of this material offers a novel strategy for improving the kinetics and stability of MgH₂.