• Amorphous scaly high-entropy borides (HEBs) with electron traps were synthesized via a facile reduction method, significantly enhancing the hydrogen storage properties of MgH2.
• The addition of 10wt% HEB reduced the onset dehydrogenation temperature of MgH2 to 187.4°C and lowered the activation energy from 212.78 to 65.04 kJ/mol, demonstrating superior catalytic kinetics.
• The MgH2 + 10wt% HEB composite achieved reversible hydrogen storage with a 97% retention rate after 30 cycles, maintaining a capacity of 6.47wt% H2.
• The catalytic mechanism involves the riveting of heterogeneous active sites on MgH2 surfaces during ball milling, driven by the cocktail effect and orbital hybridization of metal borides, which steadily enhance hydrogen storage reactions.