TiCrNb hydride fabricated by melt spinning as the efficient catalyst for enhancing the hydrogen storage properties of MgH2

Abstract

Magnesium hydride (MgH₂) has garnered significant attention as a promising material for high-capacity hydrogen storage. However, its commercial application remains challenging due to the high operating temperature and slow reaction kinetics. In this study, melt-spun Ti₄₅Cr₄₀Nb₁₅ (with a BCC phase) hydride (designated as TiCrNbH_x−MS) was synthesized and used to form a nano-multiphase composite to improve the de-/rehydrogenation properties of MgH₂ through ball milling. The incorporation of TiCrNbH_x−MS was shown to significantly enhance the hydrogen de-/rehydrogenation properties of MgH₂. The MgH₂ + 20 wt% TiCrNbH_x−MS composite exhibits an appealing initial dehydrogenation temperature of 163 °C and can absorb hydrogen at room temperature. Notably, it releases 5.8 wt% hydrogen in 700 s at 230 °C and recharges 4.3 wt% hydrogen in just 2 mins at 150 °C. Even after 100 cycles, it retains a reversible hydrogen capacity of 4.98 wt%. Kinetic analysis revealed that the dehydrogenation rate follows the Chou surface penetration model. Microstructural analysis showed that the FCC phase of the melt-spun TiCrNbH_x−MS hydride reversibly transformed into the BCC phase during the de-/rehydrogenation process in the composite. Numerous phase interfaces were generated and uniformly dispersed on the MgH₂ surface, providing additional hydrogen diffusion pathways and heterogeneous nucleation sites for Mg/MgH₂, thereby further improving the hydrogen de-/rehydrogenation kinetics of the system. This study offers valuable insights into the use of multiphase composites to enhance MgH₂ performance.