High entropy alloys (HEAs) have garnered considerable interest in catalysis owing to their unique characteristics, while transition metal oxides remain widely studied as classical catalysts. Herein, a novel core-shell FeCoNiCrCu/Fe₂O₃@C catalyst coated by a micro- and nano-scale amorphous carbon layer was prepared via a relatively facile synthesis method involving complexing multiple metal cations in organic solvents followed by calcination. Compared with MgH₂, the initial hydrogen desorption temperature of MgH₂ with the FeCoNiCrCu/Fe₂O₃@C catalyst decreases significantly from 290 ℃ to 172 ℃, and the peak temperature is reduced to 268 ℃. Furthermore, the catalyzed MgH₂ enables hydrogen absorption even at room temperature under 3 MPa. It also demonstrates excellent cyclability, maintaining over 90% of its initial capacity after 50 cycles, along with progressively enhanced dehydrogenation kinetics. The excellent hydrogen storage performance of the catalyzed MgH₂ is contributed to the synergistic interplay of catalytic components collectively, including the “hydrogen diffusion channel” effect of the in-situ generated Co₃Fe₇, the “hydrogen pump effect” exhibited by the reversible catalytic phase pair Mg₂Ni(Cu)/Mg₂Ni(Cu)H₄, as well as the multiphase interface composed of HEAs FeCoNiCrCu, Co₃Fe₇ and MgH₂. The amorphous carbon prevents particle agglomeration. This study demonstrates that the HEAs can exhibit significant catalytic effects through rational design.

Complex metal oxide catalysts greatly accelerate the hydrogen sorption rates in the magnesium hydride system. In this study, the graphene-supported Sc₂O₃/TiO₂ catalyst is synthesized by means of a simple method, and a surprisingly synergetic effect of the Sc₂O₃-TiO₂ cocatalyst on the hydrogen storage performance of MgH₂ is observed. The MgH₂-Sc₂O₃/TiO₂@Gn composite starts to release hydrogen at 140 ℃ and reaches the peak dehydrogenation temperature at 239.9 ℃. It absorbs 6.55 wt% of H₂ in 1 min and desorbs 5.71 wt% of H₂ in 10 min at 300 ℃, showing excellent hydrogen absorption and desorption performance. Furthermore, with the decrease of the grain size and changes in the structure, the activity of the catalyst is greatly improved. The low-valent titanium and scandium and oxygen vacancies formed in the process of dehydrogenation facilitate hydrogen diffusion and electron transfer, and further improve the kinetic performance of the Mg/MgH₂-Sc₂O₃/TiO₂@Gn system. This study aims to provide insights into studying complex metal oxides as catalysts to improve hydrogen storage performance, and shed light on other catalysis-related research.