NiPd Nanoparticles Deposited on CeO2 Nanorods as Catalysts for Enhancing Hydrogen Storage in MgH2

Magnesium hydride (MgH₂) stands out as one of the most promising hydrogen storage materials due to its high hydrogen storage capacity and low cost. Nevertheless, its sluggish kinetics and remarkable stability pose significant challenges, restricting its widespread practical application. In this study, we successfully synthesized a CeO₂-supported NiPd catalyst (NiPd/CeO₂) by firmly embedding a small amount of Ni_0.5Pd_0.5 alloy nanoparticles on CeO₂ nanorods. This catalyst notably lowered the initial dehydrogenation temperature of MgH₂ from over 300 to 219 °C. When 10 wt % of the NiPd/CeO₂ was incorporated into MgH₂, the resulting composites exhibited impressive hydrogen storage kinetics. Specifically, they were able to release approximately 6 wt % H₂ within 500 s at 350 °C and absorb about 6.4 wt % H₂ in just 40 s at 250 °C. Furthermore, these composites showed excellent cycling stability, maintaining over 90% of their hydrogen storage capacity after 20 cycles. Combining multiple characterization techniques revealed that the excellent catalytic performance was primarily attributed to the rich oxygen vacancies on the CeO₂ nanorods, which facilitated the strong embedding of Ni_0.5Pd_0.5 nanoparticles on CeO₂. This, in turn, led to a synergistic effect between Ni, Pd, and CeO₂. The in situ-formed Mg₆Ni/Mg₆Pd functions as a “hydrogen pump”, facilitating enhanced hydrogen absorption and dehydrogenation processes in MgH₂. These results offer valuable insights into the design of catalysts and the identification of active species involved in modifying MgH₂.