Boosting hydrogen storage performance of MgH2 by efficient V2O3/C catalyst

Magnesium hydride (MgH₂) is deemed to a prospective high-capacity solid-state hydrogen storage material. However, slow kinetics and high desorption temperature severely limit its practical application. In this study, V₂O₃/C nanospheres composed of two-dimensional nanosheets were especially synthesized and employed as catalysts to enhance the hydrogen storage performance of MgH₂. The initial dehydrogenation temperature of the MgH₂-V₂O₃/C system was reduced to 200.4°C, with a dehydrogenation capacity of 6.69 wt%. At 300°C, the MgH₂ with 10 wt% V₂O₃/C catalyst could release 6.3 wt% H₂ in just 7 min and could start hydrogen absorption reaction at room temperature. The dehydrogenation activation energy (Ea) of the MgH₂-10 wt% V₂O₃/C system was calculated to be 88.96 ± 4.66 kJ/mol, representing an approximate 34.8 % reduction compared to the 136.43 ± 4.32 kJ/mol of ball-milled (BM) MgH₂. Moreover, the sample demonstrated exceptional cyclic stability, remaining the hydrogen storage capacity of 99.5 % after 30 cycles. In this system, in-situ elemental vanadium serves as the catalytic active site and plays a crucial catalytic role. Additionally, the carbon material helps prevent the agglomeration of MgH₂. The combined effect of these two components significantly improves the kinetic property for the MgH₂ system.