TiCrNb hydride fabricated by melt spinning as the efficient catalyst for enhancing the hydrogen storage properties of MgH2
Houqun Xiao, Luocai Yi, Huxu Lei, Yu Xu, Xiaoxuan Zhang, Huazhou Hu, Ruizhu Tang, Qian Li, Qingjun Chen
Abstract
• Melt-spun Ti 45 Cr 40 Nb 15 catalyzed MgH 2 exhibited exceptional hydrogen performance. • The onset dehydrogenated temperature of the composite is reduced to 163 °C. • The apparent activation energy E a of dehydrogenated reaction has reduced by ∼50%. • The destabilization of Mg-H bonds is preferential occurred at the phase interfaces. Magnesium hydride (MgH 2 ) 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 Ti 45 Cr 40 Nb 15 (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 MgH 2 through ball milling. The incorporation of TiCrNbH x− MS was shown to significantly enhance the hydrogen de-/rehydrogenation properties of MgH 2 . The MgH 2 + 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 MgH 2 surface, providing additional hydrogen diffusion pathways and heterogeneous nucleation sites for Mg/MgH 2 , thereby further improving the hydrogen de-/rehydrogenation kinetics of the system. This study offers valuable insights into the use of multiphase composites to enhance MgH 2 performance.