Effect of MgH2 Adsorbed on Different Crystal Planes of CeO2 for Improvement of Hydrogen Absorption/Desorption

Abstract

Magnesium hydride (MgH₂) is widely recognized as a prominent solid-state hydrogen storage material, notable for its high hydrogen storage capacity and lightweight characteristics. However, its application is hindered by a high dehydrogenation temperature and slow kinetics. Ceria serves as a highly effective catalyst for enhancing the kinetic performance of MgH₂, primarily due to its rich concentration of oxygen vacancies. In this work, cerium dioxide (CeO₂) crystals with different morphology are prepared (nanoparticles and nanorods), which exposed different crystal facets (100) and (111), respectively. The results indicate that the (100) crystal plane exhibits a greater affinity for hydrogen atom adsorption, leading to the formation of CeH_2.73. This interaction facilitates both the dissociation of hydrogen molecules and the diffusion of hydrogen atoms, thereby enhancing the hydrogen absorption properties of MgH₂. The (111) crystal plane contains more oxygen vacancies, attracting negatively charged H^–, dissociating the Mg–H bonds, and thus improving the hydrogen desorption properties of MgH₂. In this study, we propose a strategy to optimize the morphology and crystallographic features of the catalyst to enhance its catalytic activity and thus improve the hydrogen storage performance of MgH₂.