Leaf-carbon-supported FeCo nanocatalysts enable 200 °C desorption and high reversibility in MgH2 hydrogen storage

Magnesium hydride (MgH 2 ) is a promising candidate for solid-state hydrogen storage due to its high theoretical capacity, but its application is limited by high desorption temperatures and sluggish sorption kinetics. In this work, we developed leaf-carbon-supported FeCo bimetallic nanocatalysts (FeCo/C(b)) via a facile impregnation–pyrolysis route and incorporated them into MgH 2 through high-energy ball milling. The resulting MgH 2 +10 wt% FeCo/C(b) composite exhibited a dramatically reduced onset desorption temperature of 200 °C and delivered 6.46 wt% H2 within 20 min at 300 °C. Differential scanning calorimetry revealed a desorption peak shift of ∼101 °C and a ∼19 % reduction in apparent activation energy compared with pristine MgH 2 , highlighting the pronounced kinetic improvement. Remarkably, rehydrogenation initiated at only 60 °C, with rapid uptake of ∼6.37 wt% at 175 °C under 3 MPa H 2 , and the composite maintained >99 % capacity retention after 10 cycles. Microstructural characterizations confirmed the homogeneous dispersion and stability of FeCo/C(b) in the MgH 2 matrix, while interfacial mismatch and defect engineering were identified as the key factors facilitating hydrogen diffusion. This study demonstrates that biomass-derived carbon supports, combined with Fe–Co synergistic catalysis, offer an effective and sustainable strategy to achieve low-temperature, reversible hydrogen storage in MgH 2 .