CoNi-loaded CeO2 nanorods enable in-situ multiple-hydrogen-pump catalysis for reversible MgH2 storage

Magnesium hydride (MgH 2 ) is an attractive solid-state hydrogen carrier, but its practical use is restricted by the high temperature and sluggish kinetics required for reversible hydrogen release and uptake. Here, we report a multicomponent nanocatalyst composed of Co/Ni nanoclusters anchored on CeO 2 nanorods to accelerate hydrogen exchange in MgH 2 . Incorporating 10 wt.% of the catalyst enables MgH 2 to release 6.1 wt.% H 2 within 300 s at 350 °C, while markedly improving dehydrogenation even at 250 °C. More importantly, the composite rapidly absorbs 5.3 wt.% H 2 at 125 °C and retains a reversible uptake of 2.4 wt.% H 2 at room temperature (25 °C). The catalyzed system also exhibits a reduced dehydrogenation activation energy of 78.9 kJ mol −1 and preserves over 90% of its hydrogen-storage capacity after 50 dehydrogenation/hydrogenation cycles at 300 °C. Structural analyses reveal that the dynamically generated Mg 2 NiH 4 /Mg 2 Ni and Mg 2 CoH 5 /Mg 2 Co phase pairs establish coupled hydrogen-transfer pathways that function as a “double hydrogen pump”, while the in-situ-formed CeH 2.73 further accelerates the hydrogen-pumping process and synergistically promotes Mg-H bond activation. This work demonstrates a rare-earth/transition-metal cooperative catalysis strategy for developing high-performance MgH 2 -based hydrogen-storage materials.