Hydrogen Storage Properties Of Magnesium Research Articles

Hydrogen storage properties of magnesium based alloys Mg67Ni(32-x)Nb1Alx (x = 1, 3, and 5) by using response surface methodology

Nano metals and hydrogen storage have attracted significant attention in recent years due to their numerous unique properties and wide range of applications. This study explores the synthesis of nanostructured Al and Nb-substituted Mg2Ni intermetallic compounds through high-energy ball milling and investigates their electrochemical performance for energy-related applications. The research emphasizes the critical influence of crystallinity and crystallite size on electrode material performance. Employing Response Surface Methodology (RSM), the study identifies key factors affecting discharge capacity. Notably, current density emerges as the most significant factor, contributing 73% to discharge capacity, as confirmed by perturbation plots. Interaction effects among the factors were found to be relatively insignificant concerning the chemical kinetics of the electrode material. Furthermore, a second-order polynomial equation was developed through RSM to quantitatively relate discharge capacity to composition, milling time, and current density, with a high R2 value of 98.3%. To optimize discharge capacity, a fuzzy parameter setting was generated based on the mathematical model, resulting in a predicted discharge capacity of 398.209 mAh g−1, closely aligned with actual experimental results (394.203 mAh g−1). This work showcases the significance of advanced statistical techniques in elucidating the intricate relationships governing electrochemical performance, particularly in the context of nanocrystalline materials.

Synergistic catalytic effects of ZIF-67 and transition metals (Ni, Cu, Pd, and Nb) on hydrogen storage properties of magnesium

MgTM/ZIF-67 nanocomposites were prepared by the deposition-reduction method using ZIF-67, MgCl2, and TMClx (TM = Ni, Cu, Pd, Nb) as raw materials. The dehydrogenation activation energies of MgTM/ZIF-67 (TM = Ni, Cu, Pd, Nb) nanocomposites were calculated to be 115.4 kJ mol−1 H2, 115.7 kJ mol−1 H2, 113.6 kJ mol−1 H2, and 75.8 kJ mol−1 H2, respectively; hence, the MgNb/ZIF-67 nanocomposite manifested the best comprehensive hydrogen storage performance. The hydrogen storage capacity of the MgNb/ZIF-67 nanocomposite was hardly attenuated after the 100th hydrogen absorption-desorption cycle. The dehydrogenated enthalpies of MgH2 and CoMg2H5 in MgNb/ZIF-67 hydride were calculated to be 72.4 kJ mol−1 H2 and 81.0 kJ mol−1 H2, respectively, which were lower than those of additive-free MgH2 and Mg/ZIF-67. The improved hydrogen storage properties of MgNb/ZIF-67 can be ascribed to the CoMg2–Mg(Nb) core-shell structure and the catalytic effects of NbH and niobium oxide nanocrystals.

Study on catalytic effect and mechanism of MOF (MOF = ZIF-8, ZIF-67, MOF-74) on hydrogen storage properties of magnesium

Using a deposition-reduction method, Mg/MOF nanocomposites were prepared as composites of Mg and metal-organic framework materials (MOFs = ZIF-8, ZIF-67 and MOF-74). The addition of MOFs can enhance the hydrogen storage properties of Mg. For example, within 5000 s, 0.6 wt%, 1.2 wt%, 2.7 wt%, 3.7 wt% of hydrogen were released from Mg, Mg/MOF-74, Mg/ZIF-8, Mg/ZIF-67, respectively. Activation energy values of 198.9 kJ mol−1 H2, 161.7 kJ mol−1 H2, 192.1 kJ mol−1 H2 were determined for the Mg/ZIF-8, Mg/ZIF-67, Mg/MOF-74 hydrides, which are 6 kJ mol−1 H2, 43.2 kJ mol−1 H2, and 12.8 kJ mol−1 H2 lower than that of Mg hydride, respectively. Moreover, the cyclic stability characterizing Mg hydride was significantly improved when adding ZIF-67. The hydrogen storage capacity of the Mg/ZIF-67 nanocomposite remained unchanged, even after 100 cycles of hydrogenation/dehydrogenation. This excellent cyclic stability may have resulted from the core-shell structure of the Mg/ZIF-67 nanocomposite.

Synthetical catalysis of nickel and graphene on enhanced hydrogen storage properties of magnesium

Reduced graphene-oxide-supported nickel (Ni@rGO) nanocomposite catalysts were synthesized, and incorporated into magnesium (Mg) hydrogen storage materials with the aim of improving the hydrogen storage properties of these materials. The experimental results revealed that the catalytic effect of the Ni@rGO nanocomposite on Mg was more effective than that of single nickel (Ni) nanoparticles or graphene. When heated at 100 °C, the Mg–Ni and Mg–Ni@rGO composites absorbed 4.70 wt% and 5.48 wt% of H2, respectively, whereas the pure Mg and Mg@rGO composite absorbed almost no hydrogen. The addition of the Ni@rGO composite as a catalyst yielded significant improvement in the hydrogen storage property of the Mg hydrogen storage materials. The apparent activation energy of the pure Mg sample (i.e., 163.9 kJ mol−1) decreased to 139.7 kJ mol−1 and 123.4 kJ mol−1, respectively, when the sample was modified with single rGO or Ni nanoparticles. Under the catalytic action of the Ni@rGO nanocomposites, the value decreased further to 103.5 kJ mol−1. The excellent hydrogen storage properties of the Mg–Ni@rGO composite were attributed to the catalytic effects of the highly surface-active Ni nanoparticles and the unique structure of the composite nanosheets.

Hydrogen storage properties of magnesium nanotrees investigated by a quartz crystal microbalance system

We report enhanced low temperature hydrogen storage properties of magnesium “nanotrees” fabricated by glancing angle deposition (GLAD) method. The arrays of nanotrees and conventional thin films of elemental Mg have been deposited directly onto gold coated unpolished quartz crystal substrates. Mg nanotrees were about 15 μm in height, 10 μm by 1 μm in lateral size, and were composed of “nanoleaves” of about 20 nm in thickness, 2 μm length, and 1 μm width. Hydrogen absorption and desorption properties of Mg nanotrees and thin films were investigated using a quartz crystal microbalance (QCM) testing system that is capable of measuring weight changes with a nanogram sensitivity. QCM absorption tests were performed at temperatures 100, 200, and 300 °C under 30 bars of H2 pressure. Measurements revealed that Mg nanotrees can absorb hydrogen at significantly higher weight percentage (wt%) and faster rates compared to conventional Mg films under similar conditions. Hydrogen storage of Mg thin film was observed to be at 0.02, 0.30 and 3.91 wt% (weight percentage), while it reached to 1.26, 3.75, and 5.86 wt% for nanotrees at temperatures 100, 200, and 300 °C, respectively, after 150 min. In addition, the results of desorption experiments show that Mg nanotrees can start to release hydrogen at temperatures as low as 100 °C at a rate of 0.11 wt% (vs. 0.01 wt% for thin film at the same temperature) with desorption rates reaching to 1.05 wt% at 200 °C (0.26 wt% for thin film) and 2.57 wt% at 300 °C (1.45 wt% for thin film), which are considerably lower desorption temperatures compared to previously reported values for bulk Mg (>300 °C). The enhancement in hydrogen absorption and desorption properties of Mg nanotrees is believed to originate from their thin and isolated nanoleaves that also have an improved oxidation resistance property.

Magnesium Supported on Nickel Nanobelts for Hydrogen Storage: Coupling Nanosizing and Catalysis

Magnesium nanoparticles with the mean particle size of ∼18 nm were synthesized through the thermal decomposition of di-n-butylmagnesium using Ni nanobelts as a catalyst and support with the aim of improving the hydrogen storage properties of magnesium by coupling nanosizing and catalysis. Full hydrogenation of the magnesium nanoparticles was achieved at a low temperature of 100 °C, and hydrogen release occurred at ∼230 °C. The material showed fast hydrogen absorption with good structural stability during cycling. Hydrogen desorption occurred in 200 min at 250 °C. These enhanced hydrogen storage properties were assigned to a lower activation energy (69.2 ± 2.5 kJ mol–1 H2), and the remarkably low enthalpy of hydrogenation (34.4 ± 5.4 kJ mol–1 H2) although partially compensated by a reduced entropy of 76.9 ±5.4 J K–1 mol–1 H2. The improvement of both kinetics and thermodynamics is believed to result from the coupling effects of nanosizing and catalysis.

Can γ-MgH2improve the hydrogen storage properties of magnesium?

Nanosized γ-MgH2was synthesised by electrochemical methods and this led to consecutive and reversible hydrogen uptake and release in magnesium at low temperatures.

Hydrogen storage in heavily deformed ZK60 alloy modified with 2.5 wt.% Mm addition

Severe plastic deformation techniques have been extensively used to improve hydrogen storage properties of magnesium based alloys. In this work, the commercial magnesium alloy ZK60 (Mg-6Zn-1Zr in wt.%) was modified with addition of 2.5 wt.% of mischmetal (55Ce-24La-15Nd-4Pr in wt.%) and subsequently processed by equal-channel angular pressing (ECAP) and extensive cold rolling (CR). Due to the mischmetal addition, a network of intermetallic particles was formed at the grain boundaries. Besides Zn and Zr, the particles also contained the rare-earth elements La and Ce. With CR, a breakage of intermetallics occurred, that could also have played a role in enhancing the hydrogen storage properties. Ultimately, after the combined processing of ECAP followed by CR cold rolling, a significant increase in the storage capacity and activation kinetics was observed.

The role of morphology and severe plastic deformation on the hydrogen storage properties of magnesium

In this paper we report the role of morphology and severe plastic deformation on the hydrogen storage properties of magnesium. Samples were prepared in air at room temperature by accumulative roll-bonding, filing and a combination of both processes. Accumulative roll-bonding drastically refined the microstructure of magnesium but resulted in a limited hydrogen capacity. Filing accelerated the activation of magnesium without compromising hydrogen capacity. Combining both techniques enhanced or worsened the hydrogen storage properties depending on the processing sequence. These results are explained in terms of microstructure and morphology of the samples.

The Effect of Nickel and Graphite on the Hydrogen Storage Ability of Magnesium in the First Cycle

AbstractMagnesium can serve as a solid‐state hydrogen‐storage material, and over recent years it has been taken into consideration owing to its high storage capacity. The effect of 10 wt % nickel and graphite (G) on hydrogen sorption of magnesium was compared. The powder mixture was mechanically milled for 35 h under an argon atmosphere. A Sievert apparatus was used for hydrogen sorption analysis. Scanning electron microscopy and X‐ray diffraction were used for morphological characterization. Hydrogen sorption analysis was performed at 3.5 MPa and 473 K. The results showed that graphite had a better effect than nickel on the hydrogen storage properties of magnesium owing to a greater reduction in the particle size of magnesium and the physisorption of hydrogen by graphite. The hydrogen adsorption of Mg+10 wt % G was also investigated at 2.0, 3.5, and 4.0 MPa, and it was found that the compound adsorbed 5.7 wt % hydrogen at 4.0 MPa because hydrogen could penetrate into the inner parts of the magnesium powder at higher pressure.

Enhanced hydrogen storage properties of magnesium by the synergic catalytic effect of TiH1.971 and TiH1.5 nanoparticles at room temperature

In order to improve the hydrogen sorption kinetics of Mg at room temperature, the Mg–9.2wt%TiH1.971–3.7wt%TiH1.5 nanocomposite is successfully prepared by hydrogen plasma-metal reaction (HPMR) method and hydrogenation/dehydrogenation at 673 K. The Mg nanoparticles are hexagonal in shape with the size in the range of 50–190 nm. The spherical Ti hydrides nanoparticles of about 13 nm are uniformly dispersed on the surface of Mg nanoparticles. During hydrogenation/dehydrogenation cycle, the Ti hydrides nanoparticles restrain the growth of Mg nanoparticles. The Mg–TiH1.971–TiH1.5 nanocomposite quickly absorbs 4.3 wt% H2 in 10 min at room temperature and reaches a saturation value of 5.0 wt% in 60 min. The apparent activation energies for hydrogen absorption and desorption are 12.5 and 46.2 kJ mol−1, respectively. The improved kinetics and reduced activation energy are explained in terms of the nanostructure of Mg and the synergic catalytic effect of TiH1.971–TiH1.5 nanoparticles.

The Influence of Morphology on the Hydrogen Storage Properties of Magnesium Based Materials Processed by Cold Rolling

In this communication we report the effect of macro and microstructure on the hydrogen storage properties of magnesium based materials. Magnesium hydride is an attractive material for hydrogen storage applications since it has a high hydrogen volumetric density. Furthermore, the high enthalpy of hydride formation makes it attractive for thermal energy storage applications. Besides, magnesium is an abundant and low cost material. However, the Mg/MgH2 system requires high operating temperatures due to its thermodynamic stability and slow hydrogen absorption and desorption kinetics. Magnesium’s first hydrogenation is a very long and costly process. This work aims to ameliorate this process which would effectively reduce the cost of MgH2. Commercial pure magnesium samples were processed by cold rolling. After processing, the samples presented limited hydrogen absorption due to their small surface area to volume ratio. To overcome this problem the samples were then reduced to powder using a bastard file. The samples were characterized by scanning electron microscopy and presented different morphology. Hydrogen storage properties and morphology are discussed and correlated. Results show an important improvement on the hydrogen absorption and desorption kinetics for the comminuted samples.

Catalytic Effect of Multi-Wall Carbon Nanotubes Supported Nickel on Hydrogen Storage Properties of Mg<sub>99</sub>Ni Prepared by Hydriding Combustion Synthesis

Multi-wall carbon nanotubes supported nickel (Nano-nickel/MWCNT) is added to the hydriding combustion synthesis (HCS) product of Mg99Ni by mechanical milling to yield a designed composite for improving the hydrogen storage properties of magnesium. It is revealed that there is a synergistic effect of nano-Mg2NiH4 and MWCNT on the hydrogen storage properties of Mg99Ni, which improves the hydrogenation and dehydrogenation performance when compared to adding either nano-Ni or MWCNT alone. The composite requires only 80 s to reach its saturated hydrogen capacity of 6.79mass% at 373K and desorbs 97.2% hydrogen within 1800 s at 543K. The dehydrogenation activation energy of this system is 105 kJmol11, which is much lower than that of as-received MgH2 (153 kJmol11). In addition, the composite preserves stable hydrogen storage capacity and kinetics in the hydrogenation/dehydrogenation cycles at 423K. [doi:10.2320/matertrans.MG201416]

Evolution of magnesium during reactive milling under hydrogen atmosphere with crystallitic carbon as milling aid

This paper is concerned with the changes of morphology, crystal structure and hydrogen storage properties of magnesium during reactive milling under hydrogen atmosphere with crystallitic carbon, which is prepared from anthracite coal by demineralization and carbonization, as milling aid. Experiments show that β-MgH2 of tetrahedral crystal structure with particle size of 20–60nm and geometric shape of oblique hexagonal prism predominates in the material from 3h of milling under 1MPa H2. Besides, there is γ-MgH2 of orthorhombic crystal structure in the materials from milling. The Mg particles from MgH2 dehydriding take the shape of right hexagonal prism. The carbon can prevent Mg particles from coalescing into big bulk during heating for hydrogen releasing. The endothermic peak of γ-MgH2 is 53°C lower than that of β-MgH2 in the materials from 10 to 20h of milling, and its heat absorption for dehydriding is 18kJ/mol H2 lower than that of β-MgH2.

Improving hydrogen storage properties of magnesium based alloys by equal channel angular pressing

Equal channel angular pressing was applied to a commercial magnesium alloy ZK60 in order to improve its hydrogen storage properties. The microstructure refinement and increase in the density of crystal lattice defects caused by equal channel angular pressing increase hydrogen desorption pressure, change the slope of the pressure plateau in pressure-composition isotherms, decrease the pressure hysteresis, and accelerate the hydrogen desorption kinetics. It is argued that a proper design of the defect structure of materials is a key element in the search for economically viable and environmentally acceptable solutions for mobile hydrogen storage based on metal hydrides.

Effects of carbon black, graphite and carbon nanotube additives on hydrogen storage properties of magnesium

The effects of different carbon additives: carbon black, graphite and multi-walled carbon nanotubes, on the hydrogen storage properties of magnesium were investigated and compared. Samples of Mg containing 5 wt.% additive were prepared by milling in hydrogen gas using a magnetically controlled ball mill. Structural and phase evolution were investigated using X-ray diffractometry (XRD) and morphology and microchemistry by scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS). Raman spectroscopy was used to investigate changes in the nature of carbon–carbon bonding, differential scanning calorimetry (DSC) to investigate desorption characteristics, and thermogravimetry (TG) to estimate the hydrogen storage capacity of both milled and rehydrogenated samples. There was no significant difference in the hydrogen storage capacity between the as-prepared (6.4 wt.%) and rehydrogenated (6.2 wt.%) composites, however, the rehydrogenated composite containing graphite displayed a remarkable decrease in the desorption temperature, a result which wants further investigation.

Hydrogen storage properties of magnesium based nanostructured composite materials

In this work, nanostructured composite materials Mg–Ni, Mg–Ni–La, Mg–Ni–Ce and Mg–LaNi 5 have been synthesized using the mechanical alloying process. The new materials produced have been investigated by X-ray diffraction (XRD), transition electron microscope (TEM), scanning electron microscope (SEM) and electron energy dispersion spectrum (EDS) for their phase compositions, crystal structure, grain size, particle morphology and the distribution of catalyst element. Hydrogen storage capacities and the hydriding–dehydriding kinetics of the new materials have been measured at different temperatures using a Sieverts apparatus. The results show that amorphous/nanostructured composite material Mg 50 wt.%–Ni 50 wt.% absorbs 5.9 wt.% within 5 min and desorbs 5.1 wt.% hydrogen within 15 min at 250 °C, respectively. It is confirmed that mechanical alloying that reduces particle size and introduces mechanical stress accelerates the hydrogenation kinetics of the magnesium based materials even at low temperature. But, to release the absorbed hydrogen from the mechanical alloyed materials, a high temperature is still required. It is believed that the dehydriding temperature is largely controlled by the thermodynamic stability of magnesium hydride. It is found that doping Mg–Ni nano/amorphous composite materials with lanthanum, cerium and LaNi 5 alloy reduces the hydriding and dehydriding temperatures. The composite material Mg 80 wt.%–LaNi 5 20 wt.% absorbs 1.96% hydrogen and releases 1.75 wt.% hydrogen at 25 °C, which suggests the formation of unstable hydrides. Although the stability of MgH 2 cannot be easily reduced by ball milling alone, the results suggest the thermodynamic behavior of Mg–Ni nano/amorphous composite materials can be alternated by additives such as La, LaNi 5 or other effective elements.

Hydrogen storage properties of magnesium ultrafine particles prepared by hydrogen plasma-metal reaction

Hydrogen storage properties of magnesium ultrafine particles prepared by hydrogen plasma-metal reaction