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

• A novel core-shell FeCoNiCrCu/Fe 2 O 3 @C is synthesized as the stable catalyst of MgH 2 . • The catalyst enables outstanding low-temperature hydrogen absorption kinetics and cycling stability of MgH 2 . • The synergistic “cocktail effect” of multiphase components is elucidated, revealing the mechanism of enhanced hydrogen storage property. 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/Fe 2 O 3 @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 MgH 2 , the initial hydrogen desorption temperature of MgH 2 with the FeCoNiCrCu/Fe 2 O 3 @C catalyst decreases significantly from 290 °C to 172 °C, and the peak temperature is reduced to 268 °C. Furthermore, the catalyzed MgH 2 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 MgH 2 is contributed to the synergistic interplay of catalytic components collectively, including the “hydrogen diffusion channel” effect of the in-situ generated Co 3 Fe 7 , the “hydrogen pump effect” exhibited by the reversible catalytic phase pair Mg 2 Ni(Cu)/Mg 2 Ni(Cu)H 4 , as well as the multiphase interface composed of HEAs FeCoNiCrCu, Co 3 Fe 7 and MgH 2 . The amorphous carbon prevents particle agglomeration. This study demonstrates that the HEAs can exhibit significant catalytic effects through rational design.