MgH₂ shows promise for solid-state hydrogen storage because of its high gravimetric capacity (7.6%) and ecofriendliness but cannot be easily commercialized because of its sluggish dehydrogenation/rehydrogenation kinetics and high thermodynamic stability. Herein, Ce/N–codoped TiO₂ (CN-T) synthesized using a solvothermal/calcination method was composited with MgH₂ to enhance its hydrogen storage performance. The composite with a CN-T loading of 7 wt% started releasing H₂ at 187.2 ℃ and released 6.45 wt.% H₂ in 180 s at 301 ℃, which corresponded to nearly complete dehydrogenation. The residue could be rapidly rehydrogenated, with hydrogen contents of 3.24 and 5.45 wt% achieved in 1 min at 100 ℃/20 bar H₂ and 5 min at 200 ℃/20 bar H₂, respectively. This performance enhancement was attributed to the combined effects of doped N, multivalent Ti, and Ce. The doped N weakened Mg–H bonds via charge transfer and modified the electronic state density of MgH₂. Ti catalyzed H₂ dissociation/recombination through dynamic valence cycling and D-electron injection, and the introduction of Ce³⁺ created O vacancies, which lowered the electron density of Mg–H bonds, generated strain fields for hydrogen release, provided diffusion pathways, and introduced bandgap states to strengthen electron–hydrogen coupling. Thus, this study paves the way for the commercialization of MgH₂ as a green high-capacity hydrogen carrier for diverse applications.

Magnesium hydride serves as a promising solid-state hydrogen storage material owing to its high potential. However, its practical applications are constrained by the high enthalpy of hydrogen absorption and slow kinetics. In this study, we prepared a Ni/Ti₃O₅@graphene oxide (GO) dual-heterojunction composite material via solvent heating, electrostatic adsorption, and calcination to improve the hydrogen storage capabilities of MgH₂. Adding Ni/Ti₃O₅@GO to MgH₂ lowered the initial dehydrogenation temperature of MgH₂ to 183 ℃; at a dehydrogenation temperature of 275 ℃, 6.4 wt.% of H₂ escaped from the MgH₂ bulk. In addition, the hydrogen storage material absorbed 1.8 wt.% H₂ at 30 ℃ for 30 min. The calculated activation energy of dehydrogenation was 48.221 ± 0.141 kJ·mol⁻¹, which was significantly lower than that of the ball-milled MgH₂ (112.63 ± 1.44 kJ·mol⁻¹). Mechanistic analysis results revealed that the heterojunction constructed from the multiphase compound system provided a large number of active sites and hydrogen diffusion routes, resulting in a synergistic catalytic effect that enhanced the hydrogen storage capacity of MgH₂. In this work, we clarified the compositions of fuzzy interfaces in heterostructured materials by conducting ultraviolet photoelectron spectroscopy tests and identified key composite materials for the formation of heterojunctions.

Magnesium-based hydrogen storage materials, such as MgH₂, have attracted considerable attention because of its superior hydrogen storage capacities, inexpensive, and excellent reversibility. However, their high thermodynamic stabilities and slow kinetics lead to relatively high desorption temperatures, which severely limit the wide application of MgH₂. In this study, the inclusion of vanadium induced the formation Ni-Co metal–organic frameworks (MOF) from a NiCo layered double hydroxide (LDH), thereby increasing the number of defects and vacancies, and improving the hydrogen storage properties of MgH₂. The synthesized NiCo-MOF/V-O-doped MgH₂ system demonstrates excellent hydrogen storage capacity. More specifically, 5 wt.% of H₂ was released over 20 min at a relatively low dehydrogenation temperature of 250 ℃, and almost complete dehydrogenation was achieved at 300 ℃ for 5 min. In addition, at 125 ℃, the hydrogen storage material absorbed 5.5 wt.% H₂ in 10 min. Furthermore, the activation energy of dehydrogenation was determined to be 69.588 ± 6.302 kJ ·mol⁻¹ which is significantly lower than that of the ball-milled MgH₂ (i.e., 118.649 ± 2.825 kJ ·mol⁻¹). It was therefore inferred that during dehydrogenation process, a Mg₂Ni/Mg₂NiH₄ hydrogen pump is formed by Ni, while the V-H and Co-H bonds formed by Co and V during the reaction act synergistically to catalyze the absorption and desorption of hydrogen, thereby increasing the hydrogen storage capacity of MgH₂. These experiments provide new perspectives on the commercial application of MgH₂.

Developing efficient catalysts is pivotal for advancing MgH₂-based hydrogen storage systems. In this study, a novel catalyst, graphene oxide-supported oxygen vacancy-rich Co₃O₄ and Ni nanoparticles (Ni-O_V-C@GO), was synthesized to enhance the hydrogen storage performance of MgH₂. The catalyst dramatically improved the kinetics of MgH₂, lowering the initial hydrogen desorption temperature of Ni-O_V-C@GO-MgH₂–7 to 438 K, which is 386 K lower than that of as-milled MgH₂. The composite achieved 5.0 wt% hydrogen absorption at 423 K within 600 s and retained 97.3 % capacity after 30 cycles. Notably, the activation energy for H₂ desorption was reduced to 40.78 kJ/mol, an 80 % decrease compared to pristine MgH₂. The in-situ formation of CoMg₂/CoMg₂H₅ and Mg₂Ni/Mg₂NiH₄ acted as “hydrogen pumps”, facilitating multiple hydrogen transfer pathways. Additionally, oxygen vacancies elongated Mg-H bonds, enhancing dehydrogenation kinetics through catalytic effects. These findings provide valuable insights into improving hydrogen adsorption and desorption kinetics in MgH₂-based systems.

Magnesium hydride (MgH₂) is an exceptional material for hydrogen storage, but its high desorption temperature and slow kinetics limit its applicability. In this study, the hydrogen storage performance of MgH₂ was enhanced using highly dispersed Ni-nanoparticle–doped hollow spherical vanadium nitride (Ni/VN), which was synthesized via a solvothermal process. The MgH₂ system doped with the synthesized Ni/VN exhibited an outstanding hydrogen-storage capability. Specifically, 5.6 wt.% of H₂ was released within 1 h at a relatively low temperature of 513 K, whereas 6.4 wt.% of H₂ was released within 180 s at 598 K, followed by an almost complete dehydrogenation after 10 min at 598 K. At 423 K, the developed material absorbed ~6.0 wt.% of H₂ within 5 min. The activation energy for dehydrogenation was determined to be 78.07 ± 2.91 kJ·mol⁻¹, which was considerably lower than that of MgH₂ produced by ball milling (120.89 ± 5.74 kJ·mol⁻¹), corresponding to a reduction of 35.4%. It was deduced that the formation of Mg₂Ni/Mg₂NiH₄ (hydrogen pump) through the reaction of Ni nanoparticles during dehydrogenation/hydrogenation facilitated hydrogen transport and synergistically catalyzed hydrogen absorption and desorption by MgH₂, improving its hydrogen storage capability. These findings offer novel perspectives for the utilization of MgH₂ in large-scale applications.