Hydrogen Sorption Research Articles

Bridging Materials and Analytics: A Comprehensive Review of Characterization Approaches in Metal-Based Solid-State Hydrogen Storage.

The advancement of solid-state hydrogen storage materials is critical for the realization of a sustainable hydrogen economy. This comprehensive review elucidates the state-of-the-art characterization techniques employed in solid-state hydrogen storage research, emphasizing their principles, advantages, limitations, and synergistic applications. We critically analyze conventional methods such as the Sieverts technique, gravimetric analysis, and secondary ion mass spectrometry (SIMS), alongside composite and structure approaches including Raman spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM). This review highlights the crucial role of in situ and operando characterization in unraveling the complex mechanisms of hydrogen sorption and desorption. We address the challenges associated with characterizing metal-based solid-state hydrogen storage materials discussing innovative strategies to overcome these obstacles. Furthermore, we explore the integration of advanced computational modeling and data-driven approaches with experimental techniques to enhance our understanding of hydrogen-material interactions at the atomic and molecular levels. This paper also provides a critical assessment of the practical considerations in characterization, including equipment accessibility, sample preparation protocols, and cost-effectiveness. By synthesizing recent advancements and identifying key research directions, this review aims to guide future efforts in the development and optimization of high-performance solid-state hydrogen storage materials, ultimately contributing to the broader goal of sustainable energy systems.

Liquid Phase-Made Aluminum Nanoparticles and Their Hydrogen Sorption as Aluminum/LiH Composite

Liquid Phase-Made Aluminum Nanoparticles and Their Hydrogen Sorption as Aluminum/LiH Composite

Hydrogenation Properties of the Ti45Zr38-xYxNi17 (5 ≤ x ≤ 10) and the Ti45-zYzZr38Ni17 (5 ≤ z ≤ 15) Mechanically Alloyed Materials.

The amorphous materials of the Ti45Zr38Ni17 composition synthesized by mechanical alloying are widely recognized for their ability to store hydrogen with gravimetric densities above 2 wt.%. It is also known that those alloys can form a quasicrystalline state after thermal treatment and their structural and hydrogen sorption properties can be altered by doping with various elements. Therefore, in this paper, the results of the studies on the Ti45Zr38Ni17 system with yttrium substituted for titanium and zirconium are presented. We demonstrate that these alloys are able to absorb hydrogen with a concentration of up to 2.7 wt.% while retaining their amorphous structure and they transform into the unique glassy-quasicrystal phase upon annealing. Furthermore, we demonstrate that the in-situ hydrogenation of those new materials is an effortless procedure in which the decomposition of the alloy can be avoided. Moreover, we prove that, in that process, hydrogen does not bind to any specific component of the alloy, which would otherwise cause the formation of simple hydrides or nanoclusters.

First-principles study on impact of Mo doping on the formation enthalpy and electronic structure of Li2MgN2H2 material

The influence of Mo doping on the formation enthalpy and electronic structure of Li2MgN2H2 material, as well as the specific improvement mechanism of its hydrogen storage properties, were investigated by employing the first-principles calculation method. The calculation results exhibit that when Mo is doped into the Li2MgN2H2 material, it is more inclined to take up Mg lattice site at the 8c position. For the Li2MgN2H2 material, Mo doping can effectively reduce its formation enthalpy by ca. 91.16 kJ/mol, thus resulting in the reduction of its structural stability. Moreover, when the Li2MgN2H2 material is doped with Mo, its cell volume increases, and its band gap narrows obviously. Meanwhile, the strong force between Mo and N causes the bond strengths of N–H and Li–N to weaken significantly. The aforementioned factors are beneficial to the improvement of its hydrogen sorption kinetics. This work aims to provide theoretical guidance for further development of new efficient catalysts to promote the Li–Mg–N–H material's application.

Effect of Alloying on the Hydrogen Sorption in Ti–Zr–Mn-Based Alloys. Pt. 1: C14-Type Laves-Phase-Based Alloys

The alloys of the Ti–Zr–Mn system based on the C14-type Laves phase are considered as ones of the most promising materials for safe storage and transportation of hydrogen. These alloys have appropriate parameters for activating the processes of absorption and release of hydrogen, a low cost, and a fairly high cyclic stability. In this work, the microstructure and phase composition of the starting alloys and the crystal structure of the hydrides synthesized from them are studied. Possible ways to reduce the cost of the final products are shown. The fact that changing the method of the alloy fabrication does not significantly affect its hydrogen absorption properties is shown. On the example of the considered alloys, it is shown that, as expected, alloying with an element with a larger atomic radius that forms a stable chemical compound with hydrogen results in an increase in the hydrogen capacity. This is explained by both the increased radius of the tetrahedral interstitial sites, where hydrogen atoms are located after dissolution, and the higher total amount of the element interacting with hydrogen.

Core-shell structured Ni@C based additive for magnesium hydride system towards efficient hydrogen sorption kinetics

Magnesium hydride is a potential candidate for storing hydrogen; however, due to its slow kinetics and stable thermodynamics it is difficult to use in real-world applications. In this work, we successfully synthesized different composites of Ni@C with MgH2 to improve its kinetics. Experimental results indicate better performance of all catalyzed samples as compared to the pristine MgH2. Especially, the addition of core-shell structured Ni@C enabled MgH2 to desorb hydrogen at 252 °C, which is 56 °C lower than the milled MgH2. The apparent activation energy of dehydrogenation decreased from 109.2 ± 4.1 kJ/mol (milled MgH2) to 83.1 ± 0.3 kJ/mol (catalyzed MgH2). This kinetic enhancement can be attributed to the synergistic effects of Ni, making dissociation and recombination for hydrogen easier, and the C species, inhibiting particle agglomeration. PCT measurement showed that catalysts did not alter the process thermodynamics. In the cycle stability test of NG3:10: 2, the hydrogen storage capacity was retained at 75 % after 20th cycle and only falls by about 1.6 wt percent. In addition, XRD and SEM demonstrated that the novel species of Ni@C and Mg2Ni/Mg2NiH4 together increased the absorption and dissociation of hydrogen.

Crystal structure and hydrogen sorption properties of Nd0.5Y0.5MgNi4-xCox alloys (x = 0–3)

The gas-phase and electrochemical hydrogenation properties of Nd0.5Y0.5MgNi4-xCox (where x varies from 0 to 3) were studied. Samples were prepared using sintering and annealing procedures. X-ray diffraction analysis indicated that all the alloys were single-phase. The alloys readily absorbed hydrogen, and the crystal structures of the resulting saturated hydrides were refined. Nd0.5Y0.5MgNi4H4.2 and Nd0.5Y0.5MgNi3CoH4.4 belong to the NdMgNi4H3.6 structural type, while Nd0.5Y0.5MgNi2Co2H5.5 and Nd0.5Y0.5MgNiCo3H6.0 belong to the LaMgNi4H4.85 structural type. Electrochemical studies revealed that the maximum discharge capacity of Nd0.5Y0.5MgNi4-xCox electrodes increased from 236 mAh/g to 328 mAh/g as the cobalt content increased. The high-rate dischargeability (HRD1000) initially decreased from 48 % to 7 % with increasing cobalt content, but then increased to 32 % at the highest cobalt concentration. Additionally, the electrochemical kinetic properties were determined and compared for these electrodes, including the charge-transfer resistance (Rct), polarization resistance (Rp), exchange current density (I0), limiting current density (IL), and hydrogen diffusion coefficient (DH).

Impact of ligand fields on Kubas interaction of open copper sites in MOFs with hydrogen molecules: an electronic structural insight.

We investigate hydrogen sorption on open copper sites in various ligand coordinations of metal-organic frameworks (MOFs), including the triangular T(CuL3) in MFU-4l, the linear L(CuL2) in NU2100, and the paddlewheel P(CuL4)2 in HKUST-1 from an electronic structure perspective using DFT calculations. The ligand-field-induced splitting of d states and spd hybridizations in copper are thoroughly examined. The hybridization between Cu s, p, and d orbitals occurs in various forms to optimize the Coulomb repulsion of different ligand fields. Despite the Cu+ oxidation state, which is typically conducive to strong Kubas interactions with hydrogen molecules, the vacant spd z 2 hybrid orbitals of the open copper site in the L(CuL2) coordination are unsuitable for facilitating electron forward donation, thereby preventing effective hydrogen adsorption. In contrast, the vacant spd z 2 hybrid orbitals in the T(CuL3) and P(CuL4)2 coordinations can engage in electron forward donations, forming bonding states between the Cu spd z 2 and H2 σ bonding orbitals. The forward donation in the T(CuL3) configuration is significantly stronger than in the P(CuL4)2 configuration due to both the lower energy of the vacant orbitals and the larger contributions of p and d z 2 characters to the hybrid orbital. Additionally, the occupied Cu pd xz/yz and pd x 2-y 2 hybrid orbitals in the T(CuL3) configuration promote electron back donation to the H2 σ* antibonding orbital, leading to the formation of π bonding states. In the P(CuL4)2 coordination, the repulsion from the electron density distributed over the surrounding ligands prevents the H2 molecule from approaching the copper center closely enough for the back donation to occur. The complete Kubas interaction, involving both forward and back electron donations, results in a large dihydrogen-copper binding energy of 37.6 kJ mol-1 in the T(CuL3) coordination. In contrast, the binding energy of 10.6 kJ mol-1 in the P(CuL4)2 coordination is primarily driven by electrostatic interactions with a minor contribution of the Kubas-like forward donation interaction. This analysis highlights the pivotal role of coordination environments in determining the hydrogen sorption properties of MOFs.

Mixed Metal Amide-Hydride Solid Solutions for Energy Storage Applications

Metal amide-hydride materials have been extensively studied for usage in energy applications, especially as solid electrolytes for all-solid-state batteries and as hydrogen storage. In specific cases, the formation of mixed metal amide hydride solid solutions promotes fast hydrogen sorption kinetics and tune the thermodynamics, allowing hydrogen absorption/desorption below 150 °C in hydrogen storage systems. In addition, these intermediates, such as Li2(BH4)(NH2) or Li4(BH4)(NH2)3 are potentially ionic conductors that can be used as solid electrolytes for solid-state batteries’ applications. In this work, a series of M-N-H solid solution structures based on mixed MNH2-MH materials of Group 1 elements (M = K, Rb, Cs and their combinations), such as KNH2-KH, KNH2-RbH, RbNH2-KH, RbNH2-CsH, RbNH2-CsNH2, etc., are reported. The results obtained by experimental determination (e.g., ex-situ XRD / in-situ synchrotron powder X-ray diffraction, IR, 1H 2D solid-state MAS NMR, QENS) and theoretical calculations (e.g., molecular dynamics calculations) confirm the formation of mixed metal amide hydride solid solutions associated with an exchange between both anionic (NH2 - and H-) and cationic species (K, Rb and Cs). These structurally disordered solid solutions exhibit high ionic conductivity compared to the pure materials, e.g., mixed RbNH2-CsNH2 shows an ionic conductivity in the range of 4×10-5 S×cm-1 at 373 K compared to that of pure RbNH2 and CsNH2 (< 10-7 S×cm-1 at the same condition). Although this solid solution exhibits only moderate ionic conductivity, it offers the possibility of tuning the functional and physical properties of mixed metal amide-hydrides by structural modification.

Al–Cu–Fe–Ni–Ti high entropy alloy nanoparticles as new catalyst for hydrogen sorption in MgH2

The earth's abundance of magnesium hydride (MgH2), along with its favorable qualities like high capacity, excellent reversibility, and cost-effectiveness under mild hydrogenation conditions, make it a potential material for hydrogen storage. Its practical applicability is limited by unfavorable thermodynamics and kinetics, despite these advantages. In this work, we investigate the use of a leached form of the mechanically alloyed high entropy alloy (HEA) Al–Cu–Fe–Ni–Ti as a catalyst to improve the hydrogen storage capabilities of MgH2. The onset desorption temperature of MgH2 is significantly reduced from 360 °C (for as-received MgH2) to 200 °C when catalyzed by the previously stated HEA catalyst. In addition, the catalyst exhibits enhanced kinetics, as it can absorb around 6.2 wt. % in just 2.3 min. at 300 °C and 15 atm of hydrogen pressure, and desorb approximately 5.8 wt. % in 3.8 min. When compared to other known catalysts, these results show some of the lowest desorption temperatures for MgH2. Furthermore, MgH2 catalyzed by the leached form of Al–Cu–Fe–Ni–Ti HEA exhibits good cyclic stability for up to 21 cycles, with just a small variation of about ∼0.02 wt. %. A thorough analysis using X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy have been carried out. We suggest a workable catalytic mechanism for the high entropy alloy Al–Cu–Fe–Ni–Ti on MgH2 based on these findings.

Improved heat transport and hydrogen sorption rate in the electric field aligned, graphite/magnesium hydride composites

Improved heat transport and hydrogen sorption rate in the electric field aligned, graphite/magnesium hydride composites

Development of a high-pressure 700 bar metal hydride hydrogen compressor

HySA Systems and TF Design have recently developed a single-stage prototype high-pressure metal hydride hydrogen compressor (MHHC) which is able to compress hydrogen from 100 to >700 bar at the working temperatures from 20 to 150 °C, with estimated productivity about 1 Nm3/h. The MHHC comprises of two 2 m-long fibre-wound high-pressure MH containers developed by the authors earlier and assembled in two modules operating in a mode of a cyclic lower-pressure H2 absorption (on cooling) and high-pressure H2 desorption (on heating). The containers operate using a self-developed multicomponent C14 Laves type Ti–based AB2 intermetallic alloy. The article considers phase-structural and hydrogen sorption properties of the utilized metal hydride material, hydrogen compression performances of the metal hydride container, as well as layout and the expected performance characteristics of the compressor assembly.

AB5-based metal hydride embedded in polyethylene and polymethylmethacrylate for hydrogen storage

Loose powder in metal hydride reactors poses challenges, such as poor thermal conductivity and tube deformation. To address these issues, the metal powder can be encapsulated in a polymer-based matrix to form pellets. This encapsulation helps make the pellets oxygen-impermeable, capable of accommodating the volumetric expansion of metal hydrides, and increases system processability. This study investigates the use of polymer-based pellets containing AB5-based compounds for ambient hydrogen storage. Polymers were selected using ANSYS Granta software, and polyethylene and polymethylmethacrylate were chosen. The AB5 alloy activation in the pellet occurs efficiently after 3 min at 20 °C and 30 bar of hydrogen, facilitated by ball milling-induced reactive surfaces and increased grain boundaries. The optimized pellet, comprising 90 wt% AB5 powder in a PE matrix, exhibits stable hydrogen storage properties, with good mechanical resistance and minimal powder loss (below 3%) over 20 hydrogen sorption cycles in an in-house fabricated single-tube metal hydride reactor.

Catalytic mechanism of Nb2O5 and Ni on hydrogen storage properties of CeMg12-type alloy for automatic weather station emergency fuel cell

In this paper, CeMg12/Ni/Nb2O5 was prepared by mechanical ball milling technology for the sake of probing into the impact of Ni and Nb2O5 on microstructure and hydrogen sorption properties of alloys. The microstructure research results indicate that adding Nb2O5 can promote the formation of nanocrystal structure; through ball milling the Nb2O5 dispersed on the surface of alloy particles uniformly enhances the surface activity of the alloy and improves the hydrogen absorption and releasing kinetics of the alloy. The research on hydrogen absorption performance shows that the addition of Nb2O5 can significantly increase the hydrogen release platform pressure of the alloy hydride, the enthalpy value of hydrogen releasing process drops from 74.82 kJ/mol to 71.07 kJ/mol when the content of Nb2O5 is increased from 0 wt% to 9 wt%, the above qualitative and quantitative discussion further proves that Nb2O5 is beneficial for amending the thermodynamic stability of alloy hydride. Besides, adding Nb2O5 can remarkably reduce the hydrogen dissociation activation energy of experimental alloy hydride, ameliorating the dynamic performances of hydrogen release. The alloy with 9 wt% Nb2O5 has the smallest activation energy and the best performances of hydrogen release.

Effect of preparation routes on the performance of a multi-component AB2-type hydrogen storage alloy

This article presents experimental results on the preparation and characterisation of a multi-component AB2–type intermetallic hydrogen storage alloy (A = Ti0.85Zr0.15, B = Mn1.22Ni0.22Cr0.2V0.3Fe0.06). The alloy samples were prepared by induction melting using Y2O3-lined alumo-silica and graphite crucibles. The characterisation results were compared with the ones for the reference sample of the same composition prepared by arc melting. It has been shown that the induction-melted samples exhibit reduced hydrogen sorption capacities and sloping plateaux on the pressure composition isotherms (PCI’s). The origin of the observed effects has been shown to be in the inhomogeneity of the induction-melted alloys and their contamination due to crucible—melt interaction, particularly pronounced for the alloy melted in the alumo-silica crucible; this alloy was additionally characterised by the decrease of Zr/Ti ratio and, in turn, higher plateau pressures of the PCI’s.

A statistical physics approach to hydrogen sorption-desorption isotherms in LaNi4.3Fe0.7

This study explores experimental hydrogen sorption and desorption isotherms on LaNi4.3Fe0.7 at four temperatures, employing different statistical physics models based on the grand canonical ensemble. The choice of the most appropriate model considered statistical parameters and physical analysis of the estimated parameters, culminating in selecting the monolayer model with two types of energies. The detailed analysis of these parameters provides an improved understanding of the process, highlighting the presence of hysteresis in the H2sorption and desorption in the metallic alloy. The sorption and desorption energies determined for this model vary between 82 and 109 kJmol−1, indicating a predominant chemical mechanism. Calculations of thermodynamic potentials suggest that the processes are exothermic and spontaneous. When comparing with other alloys of the same base, we observed that adding Fe presents similar trends in the model parameters, contributing to subtle improvements in the process.

Spatial Graphene Structures with Potential for Hydrogen Storage

Spatial graphene is a 3D structure of a 2D material that preserves its main features. Its production can be originated from the water solution of graphene oxide (GO). The main steps of the method include the crosslinking of flakes of graphene via treatment with hydrazine, followed by the reduction of the pillared graphene oxide (pGO) with hydrogen overpressure at 700 °C, and further decoration with catalytic metal (palladium). Experimental research achieved the formation of reduced pillared graphene oxide (r:pGO), a porous material with a surface area equal to 340 m2/g. The transition from pGO to r:pGO was associated with a 10-fold increase in pore volume and the further reduction of remaining oxides after the action of hydrazine. The open porosity of this material seems ideal for potential applications in the energy industry (for hydrogen storage, in batteries, or in electrochemical and catalytic processes). The hydrogen sorption potential of the spatial graphene-based material decorated with 6 wt.% of palladium reached 0.36 wt.%, over 10 times more than that of pure metal. The potential of this material for industrial use requires further refining of the elaborated procedure, especially concerning the parameters of substrate materials.

STUDY OF HYDROGEN-HELIUM PERMEABILITY OF SILICATE MICROSPHERES AND SORBENT BASED ON THEM

The work is devoted to research on the applicability of the membrane-sorption method for the separation of hydrogen-helium mixtures. The sorption dependences of hydrogen and helium absorption were experimentally obtained for synthetic hollow microspheres made of sodium borosilicate glass of the MS-V-1L type, silica microspheres and granular sorbent based on MS-V-1L microspheres. A significant difference in the rates of sorption processes of hydrogen and helium for the sorbents under study was shown. Based on the gas diffusion model, the kinetic characteristics of absorption, permeability and selectivity coefficients, and dynamic characteristics of the processes of sorption of hydrogen and helium of heliumhydrogen mixtures of various compositions by these sorbents were determined. For silica microspheres, the selectivity coefficient with respect to hydrogen and helium at T = 24 C exceeds 130, and for a granular sorbent based on MS-V-1L microspheres it is about 1000 at T =110 C. The high selectivity values of the studied sorbents confirm the possibility and efficiency of using the membrane-sorption method for the separation of hydrogen-helium mixtures.

Crystal, electronic structure and hydrogenation properties of the Mg5.57Ni16Ge7.43 cluster phase with a new type of polyhedron.

The ternary germanide Mg5.57Ni16Ge7.43 (cubic, space group Fm-3m, cF116) belongs to the structural family based on the Th6Mn23-type. The Ge1 and Ge2 atoms fully occupy the 4a (m-3m symmetry) and 24d (m.mm) sites, respectively. The Ni1 and Ni2 atoms both fully occupy two 32f sites (.3m symmetry). The Mg/Ge statistical mixture occupies the 24e site with 4m.m symmetry. The structure of the title compound contains a three-core-shell cluster. At (0,0,0), there is a Ge1 atom which is surrounded by eight Ni atoms at the vertices of a cube and consequently six Mg atoms at the vertices of an octahedron. These surrounded eight Ni and six Mg atoms form a [Ge1Ni8(Mg/Ge)6] rhombic dodecahedron with a coordination number of 14. The [GeNi8(Mg/Ge)6] rhombic dodecahedron is encapsulated within the [Ni24] rhombicuboctahedron, which is again encapsulated within an [Ni32(Mg/Ge)24] pentacontatetrahedron; thus, the three-core-shell cluster [GeNi8(Mg/Ge)6@Ni24@Ni32(Mg/Ge)24] results. The pentacontatetrahedron is a new representative of Pavlyuk's polyhedra group based on pentagonal, tetragonal and trigonal faces. The dominance of the metallic type of bonding between atoms in the Mg5.57Ni16Ge7.43 structure is confirmed by the results of the electronic structure calculations. The hydrogen sorption capacity of this intermetallic at 570 K reaches 0.70 wt% H2.

The influence of trihaloacetic acids on the hydrogen sorption properties of palladium nanoparticles-modified AB5 alloy in aprotic ionic liquid: Towards ionic liquid-based electrolytes for hydride batteries

Binary mixtures of acetic acid/trihaloacetic acids with aprotic ionic liquid – 1-ethyl-3-methylimidazolium methanesulfonate ([EMIM][MS]) are used as electrolytes for hydrogen electrosorption measurements. Preliminary studies are performed with palladium limited volume electrode to determine optimum concentration of the acid additives for hydrogen capacity and physicochemical properties of the electrolytes. The results obtained for trichloro- and tribromoacetic acid indicate that their decarboxylation occurs after mixing with [EMIM][MS] and dissolution of palladium is observed in contact with the decomposed electrolyte. Research on hydrogen capacity of palladium nanoparticles-modified AB5-type alloy is performed in mixtures of acetic acid and trifluoroacetic acid of optimum concentration. The best electrochemical performance is demonstrated by 2 M acetic acid/[EMIM][MS] mixture. The determined value of specific capacity of the investigated hydrogen absorbing material reaches 230 mAh g−1 and is close to that previously obtained from aqueous solutions of acids or bases.