Enhancing Hydrogen Storage Performance of Magnesium Hydride via the In Situ Formed Co/La4Co3O9 Heterostructure Derived from a Three-Dimensional Network LaCoO3

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.