Hydrogen Storage In Metal Research Articles

Topological data analysis enhanced prediction of hydrogen storage in metal–organic frameworks (MOFs)

Machine learning model has been developed for the prediction of hydrogen storage capacity of MOFs. To account the complex structure of MOFs, persistent homology is used.

In situ TEM studies on hydrogen-related issues: hydrogen storage, hydrogen embrittlement, fuel cells and electrolysis.

Hydrogen is attracting attention as an energy carrier for realizing a low-carbon society, because it can directly convert the energy obtained from chemical reactions into electrical energy without carbon dioxide emissions. This paper presents in situ transmission electron microscopy (TEM) observations related to hydrogen storage in metal and metal hydrides, hydrogen embrittlement of metallic materials used for storing and transporting hydrogen in containers and pipes, and fuel cells and water electrolysis using metal catalysts and oxides as electrode materials. All of these processes are important for practical applications of hydrogen. Numerous in situ TEM studies have revealed the microscopic structural changes when hydrogen reacts with the materials, when hydrogen is solidly dissolved in the materials and during the operation of the material. This review is expected to facilitate further development of TEM operando observations of hydrogen-related materials.

Dry water consisting of nano SiO2 modified by fluorinated surfactant: Applied to AlH3 explosion suppression

AlH3 has a high explosion risk due to rapid hydrogen evolution, and explosion suppression is necessary to reduce explosion hazard. Herein, we apply a common fire extinguishing agent, fluorinated surfactant, to suppress hydrogen in AlH3. This stable composite suppressant has a structure resembling dry water, a dilute aqueous solution of FS-50 encapsulated by fumed phase SiO2, which not only improves suppression effect but also significantly reduces the damage of fluorine to the environment. Fluorinated intermediate radicals F, CF, CF3, CHF, CHF2, etc. produced by decomposition of FS-50 interrupt the chain reaction of flame radicals H, O, OH to produce (-CH2-CF2-)n and stable product HF. Additionally, the outflow of fluorinated compounds mixes with water and SiO2 to form a cladding layer, which prevents heat propagating from the reaction zone to preheating zone. Our work will pave the way for the widespread and safe application of light metal hydrogen storage materials.

DFT insights on structural, electronic, optical and mechanical properties of double perovskites X2FeH6 (X = Ca and Sr) for hydrogen-storage applications

Hydrogen has been delivered as a magnificent alternative clean energy source to alleviate the growing energy dilemma and the harmful consequences of traditional energy sources on the environment and the population. This one-of-a-kind energy-efficient technique involves storing hydrogen in solid-state compounds and then releasing it as needed for utilization in possible energy applications. Metal hydrides have shown to be highly effective hydrogen storage mechanisms in this setting. To improve the efficiency of hydrogen storage and release at standard temperatures and pressures, however, the use of metal hydrides with high gravimetric, poor thermodynamic stability and high kinetics is required. X2FeH6 (X = Ca and Sr) has promising promise for hydrogen-storage applications, with gravimetric hydrogen densities of 4.28 wt% and 2.54 wt% weight, respectively. We used the DFT technique inside the GGA + PBE framework to undertake the first comprehensive study of the structural, electronic, optical and mechanical properties of X2FeH6 (X = Ca and Sr). Structural properties indicate that both the compounds are thermodynamically stable. The Ca2FeH6 and Sr2FeH6 are semiconductors with an estimated indirect band gap of 1.67 eV and 1.37 eV, respectively. Dielectric constants, absorption, reflectivity, energy loss functions and refractive indices are among the optical characteristics determined by the calculations. The results of mechanical properties suggest that both of these hydrides fall within the category of brittle materials. These findings are crucial for the future development of metal hydrogen storage materials.

Thermodynamic Parameters for Hydrogen Storage in Metal Organic Frameworks

The global energy crisis coupled with the rising demand to decarbonize the planet, has escalated research on alternative clean energy in the changing energy mix. Owing to the abundant availability and natural inexhaustibility of hydrogen in nature, the green hydrogen has turned out to be a promising and attractive energy carrier in cars and other mobile applications. However, hydrogen production still faces challenges on storage, distribution and usage. Microporous metal-organic frameworks have become the most promising materials for hydrogen storage since they have high surface areas and chemically tunable porous structures. Thus, this study is carried out to investigate the theoretically valid equations and thermodynamic parameters for hydrogen storage in metal organic frameworks. Our calculations revealed that, an efficient hydrogen storage metal organic framework should be tuned to high overall entropy above 484

Hierarchical Structure Carbon-Coated CoNi Nanocatalysts Derived from Flower-Like Bimetal MOFs: Enhancing the Hydrogen Storage Performance of MgH2 under Mild Conditions

The construction of transition metal nanocatalysts has become an attractive way to improve the hydrogen storage performance of MgH2. However, it is still a great challenge to obtain multielement transition metal nanocatalysts, improve the hydrogen storage capacity of MgH2 under mild conditions (<573 K), and reduce the apparent activation energy of hydrogen absorption and desorption. In this work, a flower-like CoNi-MOF was successfully synthesized by sacrificing templates. After further pyrolysis, we obtained hierarchical structure flower-like MOF derivatives assembled by CoNi@C nanoparticles with an average particle size of 15.1 nm. Then, MgH2-x wt % CoNi@C nanocomposites are fabricated through the ball milling process. Due to the unique hierarchical flower-like structure of MOF derivatives, the inhibition of an amorphous carbon shell on CoNi alloy growth and agglomeration, and the synergistic catalysis of Mg2Co and Mg2Ni, the MgH2-10 wt % CoNi@C nanocomposite exhibits excellent hydrogen storage capacity under mild conditions and low apparent activation energy: At 473 K, the nanocomposite can quickly absorb 5.0 wt % H2 in 5 min, and even at 373 K, it can still absorb 4.2 wt % H2 in 60 min. At 573 and 548 K, it can release 4.8 and 3.1 wt % H2, respectively. The apparent activation energies for hydrogen absorption and desorption decrease remarkably to 24.9 and 67.3 kJ/mol, respectively, which are significantly better than those for MgH2-10 wt % Co@C (44.7 and 79.8 kJ/mol) and MgH2-10 wt % Ni@C (39.0 and 78.9 kJ/mol) nanocomposites. The first-principles calculation indicated that the hydrogen adsorption energy of the Mg–CoNi model is as low as −5.87 eV. This work provides a new strategy for the design of highly efficient multielement transition metal hydrogen storage material catalysts with a hierarchical structure.

Effects of NH4+ doping on the hydrogen storage properties of metal hydrides

Doping can modify the properties of metal hydrogen storage materials significantly. Currently, the metal doping is a frequent strategy, while the non-metal cation doping has not been examined extensively so far. In this study, the effects of NH4+ doping on the hydrogen storage properties of different metal hydrides, including TiH2, Ti0·25V0·25Nb0·25Zr0·25H2, Ti0·5V0·5H2 and VH2, are investigated by first-principles calculations. It is found that the NH4+ presents a good affinity for metal hydrides and the NH4+ incorporation leads to charge redistribution and formation of dihydrogen bond. Furthermore, the NH4+ doping in metal hydrides is favorable for enhancing the hydrogen storage capacity and decreasing the thermal stability simultaneously. The possible reason for the NH4+ doping induced destabilization in metal hydrides is the relatively weak interaction between NH4+ and hydrogen atoms.

Research progress of hydrogen energy and metal hydrogen storage materials

Hydrogen energy has become one of the most ideal energy sources due to zero pollution, but the difficulty of storage and transportation greatly limits the development of hydrogen energy. In this paper, the metal hydrogen storage materials are summarized, including metal alloys and metal-organic framework. TiFe-based hydrogen storage alloys have become one of the most promising materials because of their reversible hydrogen absorption and desorption at room temperature and low hydrogen pressure. However, the first hydrogenation requires activation at high pressure and high temperature, which is not conducive to practical application. This paper reviews the methods to improve the hydrogen storage performance of TiFe-based alloys: (1) High energy ball milling leads to the formation of microcrystalline, nanocrystalline boundaries and a large number of structural defects in the alloy, resulting in a significant increase in hydrogen diffusion channels. Meanwhile, the high surface activity of the ball-milled alloy weakens the bond energy of the Ti–H bond, thus promoting the improvement of the activation performance, hydrogen storage capacity and subsequent hydrogen absorption and desorption kinetics of the TiFe-based alloy. (2) Transition metals and rare earth elements with high valence and high affinity for hydrogen are also introduced to improve the activation performance.

High performance two-way full colors of transmission and reflection generated by hybrid Mg–TiO2 metasurfaces

Colors are carriers of information, and two-way structural colors of transmission and reflection can be used to convey significantly more information. Herein, using numerical analysis, we demonstrate metasurfaces capable of simultaneously transmitting and reflecting different colors. The low-loss hybrid Mg–TiO2 structures and transparent substrate result high saturation and wide gamut transmitted colors and complementary reflected colors. Besides, the dynamic display is possible with the hydrogen-storage metal Mg. Through simulations, we studied the potential of the proposed metasurfaces for applications, such as nanoprintings and encrypted watermarks. We expect the results of this work to be applicable to double-sided displays, anti-counterfeiting, information coding, and high-density optical data storage.

Rapid dehydrogenation of metallic materials under external electric field

The interaction between hydrogen and metal materials can lead to catastrophic failure of metallic materials, and while some metal materials can use this effect as hydrogen storage materials to make better use of hydrogen energy. If dehydrogenation is easier, it will help control hydrogen-induced degradation and the utilization of metallic hydrogen storage materials. In this study, molecular dynamics simulations are used to apply an electric field in the bicrystal hydrogen-iron system to study the diffusion coefficient of hydrogen atoms. Simultaneously, using hydrogen-charged high-strength as a model system, the effect of electric field on hydrogen content and mechanical properties of hydrogen-charged high-strength steel was also studied. Experimental and molecular simulation results show that, compared with traditional tempering, the diffusion rate of hydrogen atoms is faster and the diffusion activation energy is smaller under the action of an electric field, which is more conducive to the recovery of the mechanical properties of hydrogen-charged high-strength steel. Due to the introduction of an electric field to cause additional electrical energy, the energy barrier for hydrogen atom diffusion is lowered. At the same time, due to the influence of electromigration, the diffusion of hydrogen atoms is driven by an electron wind force, which eventually leads to an acceleration of the dehydrogenation rate.

The effects of TiH2 on the thermal decomposition performances of ammonium perchlorate-based molecular perovskite (DAP-4)

ABSTRACT In order to promote the development of molecular perovskite energetic materials, studying thermal decomposition performances of AP-based molecular perovskite energetic materials ((H2dabco)[NH4(ClO4)3], DAP-4) catalyzed by metal hydrogen storage fuel is significant. In this study, the morphology, structure and thermal decomposition characteristics of TiH2, DAP-4 and DAP-4/TiH2 composite materials were characterized and investigated. The experimental results showed that the DAP-4 peak exothermic temperature at different heating rates both showed a decreasing trend with TiH2 content increased. With 20 wt% TiH2 added, the DAP-4 peak exothermic temperature decreased from 394.3 ℃ to 352.8 ℃ (10 ℃/min heating rate), and the apparent activation energy (Ea ) also decreased from 201.5 KJ/mol to 182.3 KJ/mol. A possible catalytic thermal decomposition mechanism of perovskite catalyzed by TiH2 was proposed. This work is helpful to further understand the thermal decomposition characteristics of molecular perovskite energetic materials in the presence of metal hydrides.

Theoretical study on the structural evolution and hydrogen storage in NbHn (n = 2–15) clusters

Niobium hydrides are attractive superconductors. Exploring the formation process of niobium hydrides is essential to elucidate the mechanism of superconductivity. One of the key issues is to clarify the atomic stacking patterns of Nb and H atoms, i.e., the structural evolution of Nb–H clusters. Here, the low-energy structural isomers of NbHn (n = 2–15) clusters are determined using the CALYPSO method combined with density functional theory calculations. Geometries were fully optimized at the B3LYP/LANL2DZ/6–311++G(d) level of theory to determine global minimum structures for each size. The results indicate that NbH13 is the most stable cluster in this size range. The 4d atomic orbital of Nb and the hydrogen 1s atomic orbital participate largely to the internal binding of the NbH13 cluster. They hydrogen storage density and adsorption energy of this cluster are calculated to be 12.4 wt% and 2.58 eV, respectively. The high hydrogen storage density, suitable hydrogen adsorption energy, and high stability of NbH13 shows promise as a hydrogen storage material. These results provide fundamental information for further design of metal hydrogen storage materials.

Beyond Hydrogen Storage—Metal Hydrides as Multifunctional Materials for Energy Storage and Conversion

Following the E-MRS (European Materials Research Society) fall meeting 2019, Symposium L, this Special Issue of Inorganics, entitled “Beyond Hydrogen Storage—Metal Hydrides as Multifunctional Materials for Energy Storage and Conversion”, is dedicated to the wide range of emerging energy-related inorganic hydrogen-containing materials [...]

Self-templated carbon enhancing catalytic effect of ZrO2 nanoparticles on the excellent dehydrogenation kinetics of MgH2

Development of highly effective carbon-based multifunctional catalysts for improvement of light metal hydrogen storage materials is of great significance. Herein, a novel self-template method is proposed to synthesize carbon-encapsulated ZrO2 (5–10 nm) nanoparticles (ZrO2/C). It is found that carbon could highly improve the catalysis of ZrO2 towards MgH2 than that of ZrO2 without C. Specifically, MgH2–ZrO2/C composite remarkably reduces the onset operating temperature to 208 °C, much lower than that of MgH2–ZrO2 (248 °C) and undoped MgH2 (309 °C). Furthermore, DFT calculations were applied to elucidate the detailed catalysis mechanism of C in ZrO2/C. The results demonstrated that for the MgH2–ZrO2/C sample, Zr atoms can weaken the Mg–H bonding strength. When Mg–H bond is broken, C substrates easily “pull” the electrons from H− atoms and eliminate the bound effect of Zr on H−, thus leading to the lower hydrogen desorption energy. This work provides clear evidence to understand the synergistic catalysis of ZrO2 and C, and offers a new strategy to synthesize carbon-encapsulated metal oxides with efficient catalysis towards light metal hydrogen storage materials.

Predicting hydrogen storage capacity of metal–organic frameworks using group method of data handling

Due to their unique properties, metal–organic frameworks have exhibited excellent performance for hydrogen storage purposes in the last decade. In this regard, model development to predict the hydrogen storage in metal–organic frameworks is of a vital importance for designing and developing of efficient processes based on these new synthetic material. The objective of the present study is to develop a new model to predict the hydrogen storage capacity in metal–organic frameworks. The group method of data handling-type polynomial neural networks is implemented as a soft computing approach for model building. As an advantage, only 40% of data points are used for model development and the rest of data (60%) are designated for testing of the model. The results show that the proposed model has reasonable accuracy in which the root mean square error for the proposed model is 0.28. The model can acceptably predict effects of surface area and pressure on hydrogen storage capacity of MOFs demonstrating good ability of the proposed model for tracing physically expected trend for hydrogen storage. Additionally, the leverage measure demonstrates that the proposed model is statistically acceptable and valid. It should be noted that an artificial neural network is also developed for comparison with GMDH-PNN model, in which the results confirm that both of the models have approximately same performance and accuracy. However, due to simple mathematical structure of GMDH-PNN, it is significantly more appropriate for engineering applications.

Theoretical discovery of high capacity hydrogen storage metal tetrahydrides

Hydrogen energy is attractive energy carrier due to its high energy density, abundant, environmentally friendly and renewable etc. However, the search for the high capacity hydrogen storage material is still a great challenge. In addition, the hydrogen storage materials should have excellent catalytic activity and superior mechanical properties to meet dehydrogenation and transportation. Here, we report on a novel metal tetrahydride that can effectively improve the hydrogen storage capacity. We obtain two novel metal tetrahydrides: TiH4 and VH4 based on the phonon dispersion and thermodynamically, respectively. In particular, those metal tetrahydrides not only exhibit good dehydrogenation behavior but also show superior mechanical properties. We demonstrate that the high hydrogen storage capacity of those tetrahydrides derives from the alternative stacking of metal layer and hydrogen layer. However, the excellent dehydrogenation process is attributed to the van der Waals interaction between hydrogen layers. Finally, the thermodynamic properties of TiH4 and VH4 are discussed.

Energy-based descriptors to rapidly predict hydrogen storage in metal–organic frameworks

A new, energy-based descriptor for porous materials is highly predictive for hydrogen adsorption using an interpretable regression model.

Corrosion of Hydrogen Storage Metal Alloy LaMm-Ni4.1Al0.3Mn0.4Co0.45 in the Aqueous Solutions of Alkali Metal Hydroxides

Corrosion of pristine AB5-type metal alloy LaMm-Ni4.1Al0.3Mn0.4Co0.45 in the aqueous solutions of alkali metal hydroxides of diverse composition and concentration was tested. Correlation was observed between the alloy corrosion intensity in various hydroxide solutions, and its electrochemical capacity in these electrolytes. Mm(OH)3, CoO(OH), and nickel metal aggregates were detected among the products of selective oxidation of the alloy. High intensity corrosion of the alloy was observed in RbOH and CsOH solutions leading to formation of ternary oxides at the surface of the alloy. Presence of rubidium and cesium ions in the electrolyte were found to create an additional driving force for lanthanides (La and Ce) to leave the lattice of the alloy, thus, enhancing its corrosion. Corrosion, together with mechanical degradation, were found to be the main reasons of deactivation of LaMm-Ni4.1Al0.3Mn0.4Co0.45 alloy upon elongated electrochemical treatment.

Magneto-ionic control of magnetism using a solid-state proton pump.

Voltage-gated ion transport as a means of manipulating magnetism electrically could enable ultralow-power memory, logic and sensor technologies. Earlier work made use of electric-field-driven O2- displacement to modulate magnetism in thin films by controlling interfacial or bulk oxidation states. However, elevated temperatures are required and chemical and structural changes lead to irreversibility and device degradation. Here we show reversible and non-destructive toggling of magnetic anisotropy at room temperature using a small gate voltage through H+ pumping in all-solid-state heterostructures. We achieve 90° magnetization switching by H+ insertion at a Co/GdOx interface, with no degradation in magnetic properties after >2,000 cycles. We then demonstrate reversible anisotropy gating by hydrogen loading in Pd/Co/Pd heterostructures, making metal-metal interfaces susceptible to voltage control. The hydrogen storage metals Pd and Pt are high spin-orbit coupling materials commonly used to generate perpendicular magnetic anisotropy, Dzyaloshinskii-Moriya interaction, and spin-orbit torques in ferromagnet/heavy-metal heterostructures. Thus, our work provides a platform for voltage-controlled spin-orbitronics.

Critical Factors in Computational Characterization of Hydrogen Storage in Metal–Organic Frameworks

Inconsistencies in high-pressure H2 adsorption data and a lack of comparative experiment–theory studies have made the evaluation of both new and existing metal–organic frameworks (MOFs) challenging in the context of hydrogen storage applications. In this work, we performed grand canonical Monte Carlo (GCMC) simulations in nearly 500 experimentally refined MOF structures to examine the variance in simulation results because of the equation of state, H2 potential, and the effect of density functional theory structural optimization. We find that hydrogen capacity at 77 K and 100 bar, as well as hydrogen 100-to-5 bar deliverable capacity, is correlated more strongly with the MOF pore volume than with the MOF surface area (the latter correlation is known as the Chahine’s rule). The tested methodologies provide consistent rankings of materials. In addition, four prototypical MOFs (MOF-74, CuBTC, ZIF-8, and MOF-5) with a range of surface areas, pore structures, and surface chemistries, representative of promisin...