Hydrogen storage performance of MgH₂ modified by CeO₂−rGO composite catalyst

Magnesium hydride （MgH₂） is a promising solid-state hydrogen storage material due to its high theoretical capacity. However, its practical application is hindered by sluggish kinetics, high thermodynamic stability, and particle agglomeration, especially when modified with a single catalyst. To address these problems, a CeO₂−rGO composite catalyst was prepared by a hydrothermal method, and the CeO₂−rGO@ MgH₂ hydrogen storage composite was fabricated by compounding the catalyst with MgH₂ via high-energy ball milling. CeO₂ nanoparticles are uniformly anchored on the wrinkled rGO nanosheets. Interfacial electronic interactions among CeO₂, rGO, and MgH₂ induce more oxygen vacancies and the Ce⁴⁺/Ce³⁺ redox couple, which weaken Mg-H bonds, shorten hydrogen diffusion paths, and reduce the activation energy for dehydrogenation. Hydrogen storage performance tests demonstrate that the initial dehydrogenation temperature of CeO₂−rGO@ MgH₂ is reduced to 278 ℃, which is significantly lower than that of pure MgH₂; The composite can accomplish complete hydrogen absorption within 1 000 s with a hydrogen absorption capacity of 5.71% by mass at 150 ℃ and 4 MPa, and achieve full dehydrogenation within 80 min with a dehydrogenation capacity of 6.14% at 300 ℃. Kinetic calculation results indicate that the apparent dehydrogenation activation energy of CeO₂−rGO@ MgH₂ is 114.78 kJ/mol, 125.35 kJ/mol lower than that of MgH₂, which effectively enhances the hydrogen sorption kinetic properties of MgH₂. These results provide a new idea and experimental basis for the catalyst modification design of MgH₂-based hydrogen storage materials.