Hydrogen storage technology is related to the process of hydrogen energy market. Efficient and safe hydrogen storage materials have always been the goal pursued by people. In the past few years, oceans of materials for hydrogen storage have been researched, MgH ₂ is considered to be one of the most potential hydrogen storage materials due to its high hydrogen storage capacity, good reversibility and price advantage. However, its development has been limited by its good thermodynamic stability and slow dehydrogenation kinetics. In this paper, the improvement of hydrogen storage performance of MgH ₂ is summarized from catalyst doping, MgH ₂ nanosizing, alloying and the construction of composite system. In particular, catalyst doping and MgH ₂ nanosizing will be more effective modification strategies. With the development of nanotechnology, monatomic catalyst will also become a research hotspot. In view of the changes in thermodynamic properties caused by the nanofabrication of MgH ₂ , the loadless freestanding nano MgH ₂ will undoubtedly receive more attention.

The Mg ₂ Ni/Mg ₂ NiH ₄ formed in the original position in process of hydrogen absorption and dehydrogenation is distributed around Mg/MgH ₂ , which accelerates the rate of hydrogen absorption and dehydrogenation.

Due to its high hydrogen storage efficiency and safety, Mg/MgH₂ stands out from many solid hydrogen storage materials and is considered as one of the most promising solid hydrogen storage materials. However, thermodynamic/kinetic deficiencies of the performance of Mg/MgH₂ limit its practical applications for which a series of improvements have been carried out by scholars. This paper summarizes, analyzes and organizes the current research status of the hydrogen storage performance of Mg/MgH₂ and its improvement measures, discusses in detail the hot studies on improving the hydrogen storage performance of Mg/MgH₂ (improvement measures, such as alloying treatment, nano-treatment and catalyst doping), and focuses on the discussion and in-depth analysis of the catalytic effects and mechanisms of various metal-based catalysts on the kinetic and cyclic performance of Mg/MgH₂. Finally, the challenges and opportunities faced by Mg/MgH₂ are discussed, and strategies to improve its hydrogen storage performance are proposed to provide ideas and help for the next research in Mg/MgH₂ and the whole field of hydrogen storage.

Mg-based materials have been widely studied as potential hydrogen storage media due to their high theoretical hydrogen capacity, low cost, and abundant reserves. However, the sluggish hydrogen absorption/desorption kinetics and high thermodynamic stability of Mg-based hydrides have hindered their practical application. Ball milling has emerged as a versatile and effective technique to synthesize and modify nanostructured Mg-based hydrides with enhanced hydrogen storage properties. This review provides a comprehensive summary of the state-of-the-art progress in the ball milling of Mg-based hydrogen storage materials. The synthesis mechanisms, microstructural evolution, and hydrogen storage properties of nanocrystalline and amorphous Mg-based hydrides prepared via ball milling are systematically reviewed. The effects of various catalytic additives, including transition metals, metal oxides, carbon materials, and metal halides, on the kinetics and thermodynamics of Mg-based hydrides are discussed in detail. Furthermore, the strategies for synthesizing nanocomposite Mg-based hydrides via ball milling with other hydrides, MOFs, and carbon scaffolds are highlighted, with an emphasis on the importance of nanoconfinement and interfacial effects. Finally, the challenges and future perspectives of ball-milled Mg-based hydrides for practical on-board hydrogen storage applications are outlined. This review aims to provide valuable insights and guidance for the development of advanced Mg-based hydrogen storage materials with superior performance.

CeO₂ is an important rare earth (RE) oxide and has served as a typical oxygen storage material in practical applications. In the present study, the oxygen storage capacity (OSC) of CeO₂ was enhanced by doping with other rare earth ions (RE, RE = Yb, Y, Sm and La). A series of Undoped and RE–doped CeO₂ with different doping levels were synthesized using a solvothermal method following a subsequent calcination process, in which just Ce(NO₃)₃∙6H₂O, RE(NO₃)₃∙nH₂O, ethylene glycol and water were used as raw materials. Surprisingly, the Undoped CeO₂ was proved to be a porous material with a multilayered special morphology without any additional templates in this work. The lattice parameters of CeO₂ were refined by the least–squares method with highly pure NaCl as the internal standard for peak position calibrations, and the solubility limits of RE ions into CeO₂ were determined; the amounts of reducible–reoxidizable Ceⁿ⁺ ions were estimated by fitting the Ce 3d core–levels XPS spectra; the non–stoichiometric oxygen vacancy (V_O) defects of CeO₂ were analyzed qualitatively and quantitatively by O 1s XPS fitting and Raman scattering; and the OSC was quantified by the amount of H₂ consumption per gram of CeO₂ based on hydrogen temperature programmed reduction (H₂–TPR) measurements. The maximum [OSC] of CeO₂ appeared at 5 mol.% Yb–, 4 mol.% Y–, 4 mol.% Sm– and 7 mol.% La–doping with the values of 0.444, 0.387, 0.352 and 0.380 mmol H₂/g by an increase of 93.04, 68.26, 53.04 and 65.22%. Moreover, the dominant factor for promoting the OSC of RE–doped CeO₂ was analyzed.

Under the catalysis of Mg₂NiH₄ and Fe, and the kinetic performance of hydrogen absorption is improved. In the process of hydrogen release, Mg₂NiH₄ was transformed into Mg₂Ni, and Mg₂Ni and Fe act synergistically to facilitate the detachment of H atoms.