The Li-Mg-N-H composite material of Mg(NH2)2-2LiH is a promising candidate for hydrogen storage on-board vehicles because of its reversible hydrogen capacity of 5.6 wt%, however the apparent drawbacks of sluggish adsorption/desorption kinetics preclude its practical use. Thus these authors present a surface and interface engineering approach encompassing cerium and graphene sheets designed to alter the surface reactivity and interfacial chemistry. The improved composite of Mg(NH2)2-2LiH doped with 7.5 wt% Ce and 2 wt% graphene showed a notable improvement in performance parameters, namely, hydrogen desorption at 90 degrees C instead of the pristine 130 degrees C, and total hydrogen capacity of 4.74 wt%. Hydrogen adsorption occurs at 45 degrees C, instead of 110 degrees C for the unmodified material. The cycling capacity shows about 4.4 wt% hydrogen introduced in 160 min. at 160 degrees C. The Arrhenius analysis indicates that the desorption activation energies have dropped from 117.0 to 79.1 kJ/mol. After 10 desorption cycles the hydrogen storage capacity remains stable at 4.74 wt%, showing that excellent cycling durability is achievable. Mechanistic studies indicate that Ce forms reactive CeH2.51 during processing, and the CeH2.51 interacts synergistically with Mg(NH2)2 and LiH, thus enhancing the reactivity of the hydrogen deficient composite. Density functional theory suggests that CeH2.51 lowers the strength of the chemical bonds in Mg(NH2)2, aiding in the delivery of hydrogen. The presence of graphene further enhances the surface area and thermal conductive properties of the composite. This study demonstrates a synergistic catalytic strategy using elemental Ce and graphene, which significantly enhances the hydrogen storage properties of Mg (NH2)2-2LiH.

The brain-computer interface (BCI) is a cutting-edge technology that makes the communication between the brain and external devices possible. However, due to the low signal-to-noise ratio and non-stationarity of electroencephalography (EEG) signals, the EEG-based BCIs encounter considerable challenges. In this study, a multibranch bi-directional temporal convolutional network (MBBi-TCNet) is proposed for mental imagery decoding. By combining an attention mechanism module and a Bi-TCN module, the proposed model adopts a multi-branch network architecture to extract more useful features. By integrating the information bidirectionally, the longrange dependencies in sequences can be captured by the Bi-TCN module. The performance of the proposed model is assessed by utilizing the cross-validation method on three datasets. In the subject-dependent scenario, MBBi-TCNet achieves average classification results of 86.15 % (within-session) and 83.22 % (cross-session) on the BCIC IV2a dataset, and 80.97 % (within-session) and 86.53 % (cross-session) on the BCIC IV2b dataset, respectively. Additionally, it demonstrates an accuracy of 75.69 % (within-session) on the private dataset. In the subject-independent scenario, MBBi-TCNet also outperforms all baseline models. According to the classification results, MBBi-TCNet is superior to other state-of-the-art models. Therefore, the practical application of BCIs can be enhanced by the proposed model.

MgH2 is deemed a promising hydrogen storage medium due to its high theoretical capacity (7.6 wt%). However, its commercialization remains constrained by critical scientific hurdles, including elevated absorption/desorption temperatures, inferior kinetics, and cycling instability. Catalytic engineering enables comprehensive performance enhancement of MgH2. Herein, functionalized rare-earth perovskite nanoparticles were synthesized via sol-gel route as catalysts to enhance the comprehensive hydrogen storage properties of MgH2. The catalyzed MgH2 exhibited a drastically reduced initial dehydrogenation temperature from 320 to 214 degrees C, and enabling room-temperature hydrogen absorption. Subsequently, over 5 wt% reversible hydrogen absorption/desorption was achieved at 175/320 degrees C within 2 h. DSC analysis further revealed a notable reduction in dehydrogenation activation energy (from 128.44 to 98.62 kJ mol-1) and optimized dehydrogenation kinetics. Additionally, 5.5 wt % hydrogen release is retained after the 10th dehydrogenation cycle,and the cycle performance is well improved. Moreover, the modification mechanism was studied by multiple means of characterization. The results indicate that the incorporated LaNi0 & sdot;8Co0 & sdot;2O3 interacts with MgH2 during dehydrogenation, in-situ forming active catalytic phases (e.g., LaH3.01, Ni, Co, and Mg2Ni). The in-situ generation of diverse active phases establishes a multi-catalytic environment for MgH2 via "hydrogen spillover" and "hydrogen pump" effects, synergistically enhancing its hydrogen storage capabilities. This experiment provides a reference value for promoting the commercial application of MgH2 and designing more efficient catalysts.

Body-centered cubic (BCC) high-entropy alloys hold significant potential for solid-state hydrogen storage due to their pronounced lattice distortion and tunable compositions. To overcome the practical limitations such as low reversible capacity and difficult activation, we developed a VTiCrNbFe-based BCC HEA system using a semiempirical design approach. The Ti/Nb ratio and Ce addition were systematically optimized to regulate hydrogen storage behavior. Increasing Ti content promotes the formation of a single BCC phase but reduces capacity due to elevated valence electron concentration (VEC). The V35Ti27Cr24Nb8Fe6 composition exhibits a reversible capacity of 2.28 wt%. Notably, introducing 3 wt% Ce enables direct activation at room temperature and maintains 87 % of the capacity over 40 cycles. We elucidate the mechanism behind the improved activation, providing strategic guidance for developing practical HEA-based hydrogen storage materials.

Sodium alanate has a reversible hydrogen storage capacity of 5.6 wt% at relatively mild conditions, but it is limited in practical use because of low reaction rates and the phase separation of the reaction product. In this study, to enhance the hydrogen storage ability of sodium alanate, a one-step hydrogen pressure ball milling process was used to introduce the MXene-based carbonitride, Ti3CN, and its catalytic modification ability was compared to that of Ti3C2 on sodium alanate. The onset and peak hydrogen desorption temperatures of NaAlH4 decreased significantly from 176.9 /203.3 degrees C to 76.8/129.3 degrees C, and the activation energies for the two-step dehydrogenation process were reduced from 118/159 kJ/mol (pure NaAlH4) to 42/72 kJ/mol. In an isothermal condition at 100 degrees C, the composite material desorbed 3.30 wt% hydrogen within one hour, and the capacity retention rate kept as high as 93.7% after ten cycles of hydrogen absorption and desorption. It can be obtained that Ti3CN maintained its layered structure during the process of ball milling, and there possessed multiple active sites, such as Ti3CN, Ti0 and TiAl. Moreover, TiAl nanointermetallic phases were found to be in situ generated during the cycling process. TiAl displayed a reversible "hydrogen pump" property, acting as nucleation sites to promote the adsorption and desorption of hydrogen. At the same time, the MXene lattice promoted the dispersion of aluminum and the prevention of phase separation. The support stability provided by Ti3CN and the coupled catalytic ability of TiAl and Ti0 phases significantly improved the hydrogen desorption rate and cycling performance of NaAlH4 at low temperature. These results are valuable to the construction of an efficient solid hydrogen storage system.

This study presents the preparation of a partially etched Ti2AlN-derived composite with a combination of Ti2N, residual Ti2AlN, and in-situ TiN nanoparticles. The resultant two-dimensional ternary composite was used as a catalyst to enhance the hydrogen storage capacity of NaAlH4.Although NaAlH4 possesses a high theoretical hydrogen storage capacity of 7.4 wt%, its practical application is plagued by several problems: high temperature (similar to 180 degrees C) to release hydrogen, slow kinetics, and poor reversibility. Herein, Ti2N was prepared by etching the Ti2AlN MAX phase. The results show that the catalytic effect is optimal when the Ti2N content is 7.5 wt%, with the starting temperatures of the two-step hydrogen release from NaAlH4 decreasing from 180 degrees C and 260 degrees C to 98.4 degrees C and 163.3 degrees C, respectively. Meanwhile, the apparent activation energies of the two-step reactions decrease from 128 kJ/mol and 160 kJ/mol to 66.0 kJ/mol and 91.6 kJ/mol, respectively, with the kinetic performance significantly improved. Importantly, Ti2N/NaAlH4 composites retain more than 95% of their hydrogen storage capacity after 10 cycles. Detailed characterizations using XRD, XPS, and TEM disclosed that the coexistence of multi-phases in Ti2N/NaAlH4 composites induces synergistic catalytic effects: stable Ti2AlN provides electrically conductive pathways, while the reversible phase transformation between TiAl and TiAlHx occurs at the interface and nano-sized TiN transformed into TiAl3, enabling improved hydrogen gas dissociation. Collectively, these results provide new fundamental insights into optimizing the properties of Ti2N MXenes as catalysts in complex hydride hydrogen storage materials and establish key design principles to inspire the development of various composite materials for efficient and practical solid-state hydrogen storage systems.

Metal hydride hydrogen compressors (MHHC) are considered promising for advancing hydrogen energy technologies. Generally, MHHC consist of multi-stage hydrogen storage materials with different equilibrium pressures for compressing the hydrogen to high pressure. The primary hydrogen storage alloy in MHHC undergoes performance deterioration during prolonged operation in complex hydrogen atmospheres. This study examined the microstructure and hydrogen storage performance of the AB5-type rare earth hydrogen storage alloy after 1000 cycles, specifically La0.6Ce0.15Y0.25Ni5, utilized as the primary hydrogen storage alloy in MHHC. The findings indicate that, despite significant pulverization, the alloy retains stable lattice parameters and a single-phase CaCu5 structure, with no alteration in hydrogenation/ dehydrogenation equilibrium pressures. The hydrogen storage alloy capacity decreases from 1.39 wt% to 1.31 wt% over long cycling periods, achieving a capacity retention rate of 94.24%. The capacity reduction is primarily attributed to progressive oxidation of the active components i.e., rare earth elements La and Ce on the alloy surface during repeated hydrogenation and dehydrogenation processes, rather than pulverization or structural degradation. This research highlights a critical challenge in extending cycling performance of materials used in metal hydride compressor. Additionally, the results contribute to a deeper understanding of MHHC applications. (c) 2025 Chinese Society of Rare Earths. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

To lower the hydrogen desorption temperature of Mg-base alloys, the microstructural evolution, hydrogen absorption/desorption thermodynamics and kinetics of Mg92La1.5Ce1.5Ni5-xAlx (x = 0, 0.5, 1.0, 1.5) alloys are studied. The x = 0 alloy consists of Mg and REMgx main phases and Mg2Ni minor phase. Partial Al substitution for Ni induces Mg2Ni decomposition into AlNi and Al3.16Mg1.84, gradually eliminating Mg2Ni phase. Al also reacts with REMgx to generate REAla phase. Among the Al-containing phases, only AlNi remains stable during cycling and delivers sustained catalysis. Accordingly, the activation energy decreases significantly from 110.2 kJ mol-1 (x = 0) to 92.4 kJ mol-1 (x = 1.0), reducing the hydrogen desorption peak temperature by 23-26 degrees C. Moreover, the enthalpy change also reaches the minimum at x = 1.0, weakening hydride stability. The work provides a rational element design strategy for in-situ introducing catalytic phase to enhance the hydrogen storage performance of Mg-based alloys.

In this study, a Ce0.3Mg1.7Ni alloy was synthesized via induction melting, and activated carbon (AC) was introduced through mechanical ball milling. The effects of AC on the alloy's microstructure and hydrogen storage properties were systematically investigated. The results reveal that an appropriate amount of AC significantly enhances the overall hydrogen storage performance of the CeMgNi alloy. Specifically, AC addition refines the alloy grain size, optimizes the microstructure, and induces a porous structure that facilitates hydrogen atom diffusion. At 573 K, the incorporation of AC reduces the time to reach 90 % of hydrogen capacity by 60 % (from 90 s to 36 s) and the full saturation time by 52.8 % (from 864 s to 408 s). The dehydrogenation activation energy (Ea) reaches a minimum of 113.47 kJ & sdot;mol-1 , approximately 6.67 % lower than that of the pristine alloy. Moreover, the hydrogen absorption and desorption enthalpies decrease by 2.75 kJ & sdot;mol-1 (to -49.10 kJ & sdot;mol-1) and 5.24 kJ & sdot;mol-1 (to 57.35 kJ & sdot;mol-1), respectively. These findings demonstrate that the appropriate incorporation of AC is an effective strategy to improve the microstructure and hydrogen storage performance of CeMgNi alloys, providing valuable guidance for the development of high-performance hydrogen storage materials.

The Li–Mg–N–H (Mg(NH2)2–2LiH) system, as a high-capacity Mg-based metal hydrogen storage material (5.6 wt

Mg-based hydrogen storage alloys exhibit high hydrogen storage capacity, and attract much attention in recent years. But their hydrogen absorption/desorption performance needs to be further improved to satisfy practical applications. In this study, the comprehensive hydrogen storage properties of the La1.5Ce1.5Mg92Ni5-xCux (x = 0, 0.5, 1.0, and 1.5) alloys are effectively enhanced by doping Cu in appropriate amount, and the function mechanisms are revealed. All the alloys are composed of Mg and REMgx main phases and Mg2Ni minor phase. Cu mainly substitutes for Ni in the Mg2Ni phase, which not only promotes the formation of Mg2Ni phase, but also increases its cell volume and induces microstrain, thus, enhancing the alloys' catalytic effect, prolonging the H-Mg2(Ni,Cu) bonds and increasing the cracking tendency of the alloy particles. As a positive effect, the incubation time during activation is remarkably shortened from 2700 s (x = 0) to 1300 s (x = 0.5). Furthermore, the hydrogen absorption/desorption rate is increased and the activation energy is decreased. In particular, the alloys exhibit excellent cycling performance with increased hydrogen absorption rate and capacity after 50 cycles. The impressive cycling behavior is for the x = 0.5 alloy which also shows elevated hydrogen absorption/desorption plateau pressure and enhanced hydrogen desorption rate after cycling. The positive effects of Cu revealed in the present study shed light on the design of Mg-based alloys with improved overall hydrogen absorption/desorption properties for practical applications.

A2B7-type intermetallic compounds based on La-Y-Ni are promising H2-storage materials and have garnered widespread interest owing to their excellent properties. Herein, we report a systematic study of the structures and H2-storage properties of La2-xCexY4Ni21 (x = 0.5, 1, 1.5, and 2). All the fabricated alloys contain only Ce2Ni7 and Gd2Co7, and Ce atoms simultaneously and equally occupy the A2B4 and AB5 subunits of these two phases. With an increase in the Ce content, the gaseous H2-storage capacities of the alloys decrease, whereas the H2 absorption/desorption plateau pressures increase. The volume of the A2B4 subunit associated with the low plateau decreases more than that of the AB5 subunit related to the high plateau, leading to the elevation of the low plateau such that it matches the high plateau. Consequently, the double plateau transforms to a single plateau of the alloys. Although the maximum discharge capacities and cycling stabilities of the Ce-rich alloys are poor, their high-rate discharge (HRD) capabilities are high, specifically HRD3000 of La0.5Ce1.5Y4Ni21 can reach 66.97 %. Moreover, although Ce addition inhibits the amorphization of the alloys, it exacerbates their pulverization with severe oxidation/corrosion during cycling, resulting in rapid capacity decay. We believe that our findings will stimulate new ideas for improving the H2-storage properties of La-Y-Ni-based alloys via Ce introduction.

Hydrogen generated by hydrolysis of chemical hydrides can be used as the fuel of fuel cell and other backup power. This hydrolysis solution is advantageous because it provides a convenient and efficient means of storing and releasing hydrogen. In this work, MgH2-NaMgH3 composites were synthesized with Mg and NaH in H2 atmosphere by mechanical ball milling and high temperature hydrogenation. The composition and morphology of the composites were characterized by XRD, SEM, and TEM. The hydrolysis yield and conversion rate of MgH2NaMgH3 composites were significantly improved by NaMgH3. The hydrolysis yield of MgH2-10 mol% NaMgH3 reached 994.02 mL/g, and the conversion rate of hydrogen reached 54.56 % within 30 s. The hydrolysis of the composites in chloride solutions (NaCl, ZnCl2 and MgCl2) were investigated, in which MgCl2 solution promoted the hydrolysis the most. The hydrogen production and conversion of MgH2-8 mol% NaMgH3 in MgCl2 solution reached 1529.79 mL/g and 92.64 %, respectively. In the hydrolysis process, the addition of MgCl2 solution formed a new buffer solution, resulting in the decrease of the solubility product constant Ksp of Mg(OH)2 and the formation of an uneven passivation layer on the surface of MgH2. In addition, the heat released by NaMgH3 hydrolysis broke the Mg(OH)2 passivation layer on the surface of the material. Therefore, the hydrolysis reaction can be completely reacted in a short time.

This study focuses on the preparation of the CexMg2-xNi hydrogen storage alloy (where x = 0, 0.2, 0.3, 0.4, 0.5) through the method of vacuum induction melting. The research examined the influence of varying Ce concentrations on the characteristics of the Mg2Ni hydrogen storage alloy. The phase structure and microstructure of the synthesized alloys were characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The kinetic and thermodynamic characteristics of samples subjected to various environmental conditions were assessed using a PCT tester. Additionally, DSC curves for samples heated at rates of 5 K/min, 10 K/min, 15 K/min, and 20 K/min were obtained through TG. The results indicated that the CeMgNi4 phase, which arises from the partial substitution of Mg with Ce, did not engage in the hydrogen absorption and desorption processes, leading to a reduction in hydrogen storage capacity to a certain extent. Nevertheless, The enhancement of the overall hydrogen storage performance of the CeMgNi hydrogen storage alloy was significantly correlated with the increased content of the CeMgNi4 phase.

The magnesium based metal hydrogen storage composite system Mg(NH2 )2 -2LiH has a theoretical hydrogen storage capacity of 5.6 wt.% and is a promising hydrogen storage material for vehicles. However, its application is limited due to serious thermodynamic and kinetic barriers. Introducing efficient catalysts is an effective method to improve the hydrogen storage performance of Mg(NH2 )2 -2LiH. This article investigates for the first time the use of nano rare earth oxide CeO2 ( similar to 44.5 nm) as an efficient modifier, achieving comprehensive regulation of the hydrogen storage performance of Mg(NH2 )2 -2LiH composite system through oxygen vacancy driven catalysis. The modification mechanism of nano CeO2 is also systematically studied using density functional theory (DFT) calculations and experimental results. Research has shown that the comprehensive hydrogen storage performance of the Mg(NH2 )2 -2LiH-5 wt.% CeO2 composite system is optimal, with high hydrogen absorption and desorption kinetics and reversible performance. The initial hydrogen absorption and desorption temperatures of the composite system were significantly reduced from 110/130 degrees C to 65/80 degrees C, and the release of by-product ammonia was significantly inhibited. Under the conditions of 170 degrees C/50 min and 180 degrees C/10 0 min, 4.37 wt.% of hydrogen can be rapidly absorbed and released. After 10 cycles of hydrogen release, the hydrogen cycle retention rate increased from 85 % to nearly 100 %. Further mechanistic studies have shown that the nano CeO2-x generated in situ during hydrogen evolution can effectively weaken the Mg-N and N-H bonds of Mg(NH2 )2 , exhibiting good catalytic effects. Meanwhile, oxygen vacancies provide a fast pathway for the diffusion of hydrogen atoms in the composite system. In addition, nano CeO2-x can effectively inhibit the polycrystalline transformation of the hydrogen evolving product Li2 MgN2 H2 in the system at high temperatures, reducing the difficulty of re-hydrogenation of the system. This study provides an innovative perspective for the efficient modification of magnesium based metal hydrogen storage composite materials using rare earth based catalysts, and also provides a reference for regulating the comprehensive hydrogen storage performance of hydrogen storage materials using rare earth catalysts with oxygen vacancies. (c) 2025 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Mg-based alloys stand out as a promising candidate for solid hydrogen storage due to their advantages of high capacity, low cost, good safety etc., and efforts have been made to decrease their hydrogen desorption temperature and enhance their kinetics properties. In this study, the effects of Co on the microstructure, phase evolution, and hydrogen storage properties of La1.5Ce1.5Mg92Ni5-xCox (x = 0, 0.5, 1.0, 1.5, and 2.0) alloys are studied, whereby the positive role of Co is revealed. The alloys are composed of multiphase structures including Mg, REMgx (REMg12+RE2Mg17), and Mg2Ni phases with different Co solubilities. With increasing Co content, the activation incubation time monotonously decreases, and is totally eliminated when x = 2.0 due to the appearance of more and deeper cracks as well as Mg(Co,Ni)1.5. Moreover, P-C-T curves show that appropriate amount of Co effectively suppresses double plateau phenomenon and decreases the thermal stability of hydrides. Hydrogen absorption kinetics property is also promoted with tables0.9 decreasing from 300 -460 s (x = 0) to 66 -264 s (x = 0.5). In particular, proper Co addition effectively decreases the hydrogen desorption temperature of the alloys. An endothermal peak at lower temperature appears for the x = 0.5-1.5 alloys in the DCS curves, which are about 100 degrees C lower than those without Co. Even the 2nd endothermal peak temperature is still about 50 degrees C lower. This study sheds light on the proper elemental modification for Mg-based alloys to achieve mild conditions for hydrogen absorption and desorption.

Metal nitrogen hydride (Li-Mg-N-H) is regarded as an ideal hydrogen storage material for automotive applications due to its advantages of high hydrogen storage capacity (5.6 wt%), low operating temperature, and good cycling performance, but the comprehensive hydrogen storage performance of this material still could be improved. For this reason, this paper constructed a Li-Na-Mg-N-H composite system by synthesizing NaMgH3 to replace MgH2 in the Li-Mg-N-H system. The improvement of the hydrogen absorption and desorption properties of the composite system after the replacement of MgH2 by NaMgH3 was investigated. Various properties and test results showed that the composite system after the replacement of MgH2 by NaMgH3 showed better hydrogen absorption and desorption properties. The initial/peak hydrogen release temperatures of Li-Na-Mg-N-H decreased from 135 C/245 C to 105 C/145 C, and the apparent activation energy of hydrogen release was reduced from 114.90 to 104.05 kJ/mol which means the kinetics of hydrogen absorption and desorption was greatly improved. The mechanism study shows that NaMgH3 will react with LiNH2 and forms the intermediate product Li3Na(NH2)4 during the hydrogen release process, which changes the hydrogen desorption pathway of the composite system and thus the hydrogen absorption and desorption kinetics were improved.

This study investigates the effects of wet ball milling on the hydrogen storage properties of the Mg2Ni alloy, which was prepared using vacuum induction melting. x-ray diffraction (XRD), and transmission electron microscopy (TEM) analyses reveal that ball milling refines the alloy’s structure, generating nanocrystalline and amorphous phases that enhance hydrogen diffusion. Pressure–composition–temperature (PCT) tests and differential scanning calorimetry (DSC) analyses demonstrate that ball milling significantly improves the activation and kinetics of hydrogen absorption and desorption, while also reducing the hydrogen absorption enthalpy. Wet ball milling, utilizing petroleum ether as a medium, offers advantages such as improved temperature control and reduced oxidation. The optimal milling duration of 6 h yields the best hydrogen storage performance, characterized by decreased dehydrogenation activation energy and enhanced thermodynamic properties. Additionally, the alloy shows good cyclic stability. This work provides valuable insights into optimizing the ball-milling process for Mg2Ni hydrogen storage alloys, thereby advancing their application in hydrogen energy storage.