Core-shell FeCoNiCrCu/Fe₂O₃@C catalyst via cocktail effect for superior low-temperature hydrogen absorption kinetics and cycling stability of MgH₂

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.