Enhancing Hydrogen Storage Performance of Magnesium Hydride via the In Situ Formed Co/La₄Co₃O₉ Heterostructure...

In this work, a three-dimensional network LaCoO₃ (3D LaCoO₃) was successfully synthesized by the colloidal crystal template technique and used for optimizing the de/hydrogenation performance of magnesium hydride (MgH₂). 3D LaCoO₃ displays a unique three-dimensional network macroporous structure with interconnected pores, where LaCoO₃ nanoparticles (10-20 nm) are homogeneously anchored on the macroporous pore walls. Remarkably, MgH₂ doped with 5 wt % 3D LaCoO₃ can quickly release 6.06 wt % H₂ at 300 °C within 1200 s and absorb 6.13 wt % H₂ at 175 °C within 1800 s. Furthermore, MgH₂-5 wt % 3D LaCoO₃ exhibits a capacity retention rate of 98.12% after 10 cycles, indicating excellent reversibility. The superior catalytic performance originates from the unique 3D network structure of 3D LaCoO₃ and the in situ formed Co/La₄Co₃O₉ heterostructure during the first dehydrogenation process. The 3D network structure can make a more uniform distribution of the catalyst during ball milling, leading to more catalytic active sites. The experimental results prove that the in situ formed Co/La₄Co₃O₉ heterostructure plays a key role in enhancing the de/hydrogenation performance of MgH₂. Additionally, the DFT calculation results confirm that the Co/La₄Co₃O₉ heterostructure exhibits a higher hydrogen absorption ability due to significant electron transfer between the Co and La₄Co₃O₉ interfaces, which can facilitate the hydrogen absorption and desorption of MgH₂. These findings provide a fresh approach to designing and preparing catalysts with distinctive morphologies for MgH₂-based systems.