Pressure-composition Isotherms Research Articles

Alloying effects on the hydride formation of Zr(Mn 1− xCo x) 2

To study the alloying effects on ZrMn 2–H system, thermodynamic properties of Zr(Mn 1− x Co x ) 2 hydride were measured by volumetric method. ZrMn 2 gave a single plateau region in the pressure–composition isotherm. On the other hand, double plateaus were clearly observed in Zr(Mn 0.7Co 0.3) 2 and Zr(Mn 0.6Co 0.4) 2–H systems. The appearance of the double plateau characteristics would be explained in view of the hydrogen binding in the tetrahedral occupation sites in Zr(Mn 1− x Co x ) 2. Since the hydrogen binding in the tetrahedral 2ZrMnCo site would be less stable than that in the 2Zr2Mn site, the equilibrium pressure increases with increasing cobalt content. The appearance of the first plateau was ascribed the increase in the bonding of Mn–H in 2Zr2Mn site adjoining the 2ZrMnCo site.

Improvement of as-milled properties of mechanically alloyed LaNi 5 and application to hydrogen thermal compression

LaNi 5 was obtained from raw materials by low energy mechanical alloying. Hydriding properties of as-milled intermetallic were improved by annealing. Pressure-composition isotherms showed flat plateaus when annealing temperature was 600 °C, this value is at least 300 °C lower than the synthesis and annealing temperature of standard equilibrium methods. This low energy mechanical alloying – low temperature annealing procedure reduces the number of intermediate stages needed to scale up the fabrication of the intermetallic. After cycling this material in hydrogen, its hydriding properties were studied in the 25–90 °C range. From these results, we propose a one-stage hydrogen thermal compression scheme working between 25 °C (absorption) and 90 °C (desorption) with a compression ratio of 2.5 and a useful capacity of 1.0 mass %.

Improvement of the hydrogen storage properties and electrochemical characteristics of Ti 0.85VFe 0.15 alloy by Ce substitution

The effect of Ce substitution for Ti on the microstructure, hydrogen absorption characteristics and electrochemical properties of Ti 0.85− x Ce x VFe 0.15 ( x = 0, 0.02 and 0.05) is studied in detail. In the Ti–V–Fe series, the composition Ti 0.85VFe 0.15 which crystallizes in single phase BCC structure shows the highest hydrogen storage capacity of 3.7 wt%. In the present study, the effect of Ce addition (2 and 5 at%) on the hydrogen absorption properties of Ti 0.85VFe 0.15 has been investigated by X-ray diffraction, electron probe microanalysis (EPMA) and pressure–composition isotherm studies. The hydrogen absorption capacity is found to be higher for the Ce substituted alloys. The alloys Ti 0.85VFe 0.15, Ti 0.83Ce 0.02VFe 0.15 and Ti 0.80Ce 0.05VFe 0.15 show maximum hydrogen storage capacities of 3.7, 4.02 and 3.92 wt%, respectively. Kinetic studies show that the hydrogen absorption is quite fast for all the three alloys and they reach near saturation value in about 120 s. Electrochemical studies of the Ce (2 at%) substituted alloy, Ti 0.83Ce 0.02VFe 0.15 show higher electrocatalytic activity for the hydrogen electrode reactions as compared to Ce-free parent compound, Ti 0.85VFe 0.15.

Thermodynamics, kinetics and microstructural evolution during hydrogenation of iron-doped magnesium thin films

New results are reported suggesting that with appropriate levels of Fe doping Mg can rapidly and reversibly absorb up to 7 mass fraction (%) hydrogen at moderate temperatures and pressures useful for hydrogen storage applications. Hydrogenation kinetics and thermodynamics of Mg–4Fe at.% (+/− 1 at.%) thin films capped with Pd at temperatures ranging from 363 K to 423 K were studied by a number of different methods: in situ infrared imaging, volumetric pressure-composition isotherm (PCI) measurements, and ex situ X-ray diffraction and transmission electron microscopy. The hydride growth rate was determined by utilizing wedge-shaped films and infrared imaging; assuming formation of a continuous hydride layer, the growth rate was found to range from ≈3.8 nm/s at lower temperature to ≈36.7 nm/s at higher temperature. The apparent activation energy of the thermally activated hydrogenation kinetics was measured to be 56 kJ/mol; this value suggests that at low temperatures hydrogen diffusion along grain boundaries of MgH 2 is the mechanism controlling the hydride layer growth. Reproducible PCI measurements of 600 nm-thick uniform films showed a pressure plateau and large hysteresis; from these measurements enthalpy and entropy were estimated as 66.9 kJ/mol and 0.102 kJ/(mol∗K), respectively, which are both slightly less than values for pure magnesium (as either films or bulk). The extremely rapid and cyclable kinetics of Mg-4 at.% Fe films suggest that properly grown Mg–Fe powders of 1–2 μm size can be fully charged with hydrogen within 1 min at temperature near 150 °C (423 K), with possible practical hydrogen storage applications.

Nanosize-Induced Hydrogen Storage and Capacity Control in a Non-Hydride-Forming Element: Rhodium

We report the first example of nanosize-induced hydrogen storage in a metal that does not absorb hydrogen in its bulk form. Rhodium particles with diameters of <10 nm were found to exhibit hydrogen-storage capability, while bulk Rh does not absorb hydrogen. Hydrogen storage was confirmed by in situ powder X-ray diffraction, solid-state (2)H NMR, and hydrogen pressure-composition isotherm measurements. The hydrogen absorption capacity could be tuned by controlling the particle size.

Effect of cycling on hydrogen storage properties of Ti2CrV alloy

In the present work, we have studied the hydrogen absorption–desorption properties of the Ti2CrV alloy, and effect of cycling on the hydrogen storage capacity. The material has been characterized for the structure, morphology, pressure composition isotherms, hydrogen storage capacity, hydrogen absorption kinetics and the desorption profile at different temperatures in detail. The Ti2CrV crystallizes in body centered cubic (bcc) structure like TiCrV. The pressure composition isotherm of the alloy has been measured at room temperature and at 373K. The Ti2CrV alloy shows maximum hydrogen storage capacity of 4.37 wt.% at room temperature. The cyclic hydrogen absorption capacity of Ti2CrV alloy has been investigated at room temperature upto 10th cycle. The hydrogen storage capacity decreased progressively with cycling initially, but the alloy can maintain steady cyclic hydrogen absorption capacity 3.5 wt.% after 5th cycle. To get insight about the desorption behavior of the hydride in-situ desorption has been done at different temperatures and the amount of hydrogen desorbed has been calculated. The TG (Thermo gravimetric) and DTA analysis has been done on uncycled hydride shows that the surface poisoned sample gives a desorption onset temperature of 675K. The DSC measurement of uncycle and multi-cycled saturated hydrides shows that the hydrogen desorption temperature decreasing with cycling.

Synthesis, characterization and hydrogen storage behaviour of AB2 (ZrFe2, Zr(Fe0.75V0.25)2, Zr(Fe0.5V0.5)2 type materials

In this paper, we describe and discuss the synthesis, structural-microstructural and hydrogen storage behaviour of three AB2 type storage materials namely (a) ZrFe2, (b) Zr(Fe0.75V0.25)2 and (c) Zr(Fe0.5V0.5)2. These alloys were synthesied by radio frequency induction melting in argon atmosphere. X-ray diffraction and transmission electron microscope have been employed for structural and microstructural characterizations. The XRD study reveals that the lattice constants and the unit cell volume of ZrFe2, Zr (Fe0.75V0.25)2, Zr(Fe0.5V0.5)2 alloys, which has C14 type hexagonal Laves phase. The Surface morphology and elemental composition of these alloys were investigated by scanning electron microscope and energy dispersive X-ray analysis. The pressure composition isotherms of these alloys were investigated at room temperature and pressure ranges of 0–100 atm respectively, measured through a fully computerized PCI apparatus. As we increase the concentration of V (substituted for Fe), the total hydrogen storage capacities increased up to 1.45 wt%. This capacity is achieved in Zr(Fe0.5V0.5)2 alloy, while the reversible hydrogen storage capacity decreases due to the formation of a stable hydride phase. It has been found that the lattice constants increase with higher vanadium concentration. This is indicating that the majority of vanadium atoms reside in the B-site. The broader X-ray diffraction peaks observed in Zr(Fe0.5V0.5)2 alloy indicates a higher degree of disorder for alloys with the higher V-content. The yet another interesting feature observed in our present study is that the plateau pressure remains well below 1 atm for all the compositions.

Hydrogenation, structure and magnetic properties of La(Fe0.91Si0.09)13 hydrides and deuterides

Hydrogenation, crystal structure and magnetic properties of La(Fe0.91Si0.09)13H(D)y have been studied by pressure-composition isotherms (PCI), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and magnetization measurements. The maximum absorption capacity is found to be 1.9 H(D) atoms per formula unit as a solid solution. All hydrides and deuterides crystallize in the NaZn13-type cubic structure with the lattice parameter increasing linearly with H(D) concentration. The H(D) absorption enhances the Curie temperature significantly. The magnetic entropy change of the highly H-absorbed compound La(Fe0.91Si0.09)13H1.81 reaches ∼26 J/kg·K under a magnetic field change of 5 T near the Curie temperature TC = 350 K. No observable isotope effect seems to imply that only the magnetovolume effect is responsible for the strong interplay between magnetism and lattice.

Role of defect structure on hydrogenation properties of Zr0.9Ti0.1V2 alloy

The pseudobinary Zr0.9Ti0.1V2 compound was prepared by induction melting method. The microstructure and phase compositions were examined by the scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD). Hydrogen absorption pressure composition isotherms (P-C isotherms) were investigated by pressure reduction method using Sievert apparatus at temperature ranging from 673 to 823 K. The compositional homogeneity of the alloy was achieved under the homogenizing treatment at 1373 K for 100 h. Twin defects with {111}<022> orientation relationship were observed in the Zr0.9Ti0.1V2 annealed at 1373 K for 100 h. The phase compositions of the annealed Zr0.9Ti0.1V2 alloy could be attributed to ZrV2 Laves phase and V BCC solid solution. After hydrogenation, the alloy hydrides were consisted of ZrV2H3.6 and V4H2.88. Titanium substitution in the Zr0.9Ti0.1V2 alloy induced the formation of twin defect structures and the multiphase consisting of Laves (C15 type) related with BCC solid solution phases. The especial phase compositions and structures in the alloy were favorable to decrease the equilibrium pressure and improve the hydrogen absorption kinetics due to the twin defects in Zr0.9Ti0.1V2 comparing with the primary ZrV2 alloy. The desorption hysteresis could be decreased to a certain extent in the Ti-doped alloy under the experimental condition. V-based BCC phase in the Zr0.9Ti0.1V2 alloy could improve hydrogen absorption and desorption properties by an autocatalytic mechanism.

Investigation of hydrogen storage behavior of silicon nanoparticles

Porous Silicon (PS) freestanding film is a derivative of single crystal Si wafer. PS films obtained on electrochemical etching of p-type silicon (Si) wafer were used to synthesize Si nanoparticles by ultrasonication. 12 μm thick and 29% porous freestanding PS films were sonicated for 4 h in 120 W ultrasonication bath at 42 kHz. HRTEM image shows Si nanoparticles in the range of 8–20 nm in size. In this paper we present results of hydrogen absorption experiments conducted on Si nanoparticles. Standard Seivert’s type apparatus was used to carry out hydrogen absorption pressure composition isotherm measurements in the pressure range of 1–10 bar and in the temperature range of 29 °C–150 °C. Theoretically SiHx system has 3.44, 6.66 and 9.67 wt% of hydrogen for x = 1, 2, 3 respectively. Experimental results show maximum hydrogen uptake of 2.25 wt% at the temperature of 120 °C and at 9.76 bar pressure. Hydrogenation of Si nanoparticles exhibits frequency downshifts from 510.7 to 507.3 cm−1 in Raman spectra. Raman peaks were de-convoluted in two bands to study effect of hydrogenation on FWHM, crystallanity and elastic strain of the nanoparticles. Bonding between Si, O and H atoms were investigated using Fourier transform infrared spectroscopy(FTIR) spectroscopy. UV–Vis spectra and Tauc plots were used to discuss the relation between hydrogenation and optical band gap of the Si nanoparticles. Optical band gap was found to increase from 1.6 to 2.25 eV on subjecting Si nanoparticles to hydrogenation.

Investigations of AB 5-type hydrogen storage materials with enhanced hydrogen storage capacity

The present study deals with investigations on synthesis, characterization and hydrogenation behavior of the MmNi 5-type hydrogen storage alloys Mm 0.9Ca 0.1Ni 4.9− x Fe x Al 0.1 ( x = 0, 0.1, 0.2 and 0.3). All the alloys are synthesized by radio frequency induction melting following the composite pellet route. The X-ray diffraction pattern of dehydrogenated alloy without iron, detects peaks corresponding to calcium hydride, which are absent in the XRD pattern of the alloy with iron. The hydrogenation behavior is monitored by means of activation curves, absorption–desorption pressure-composition isotherms, hysteresis factors and desorption kinetic curves. The substitution of Iron at the place of nickel in the alloys Mm 0.9Ca 0.1Ni 4.9− x Fe x Al 0.1 ( x = 0, 0.1, 0.2 and 0.3) gives an increase in the hydrogen storage capacity as 1.82, 1.90, 2.2 and 1.95 wt% corresponding to x = 0, 0.1, 0.2 and 0.3 respectively. The correlation between structural characteristics and hydrogenation behavior is described and discussed.

Lattice defects introduced into LaNi 5-based alloys during hydrogen absorption/desorption cycling

LaNi 5-based intermetallic compounds before and after hydrogen absorption/desorption cycling were observed by transmission electron microscopy. Both a-type and c-type dislocations, which had respective Burgers vectors of 1 / 3 < 1 1 2 ¯ 0 > and <0 0 0 1> in the { 0 1 1 ¯ 0 } slip plane, were introduced into LaNi 5, LaNi 4.5Cu 0.5 and LaNi 4.5Fe 0.5 after the first absorption/desorption cycle. These alloys exhibited large difference in the equilibrium pressure between the first absorption and first desorption. Dislocations were introduced during hydrogenation in order to accommodate lattice mismatch between the metal-hydrogen solid solution and the metal hydride; furthermore, the interface between the solid solution and hydride was suggested to be the { 0 1 1 ¯ 0 } plane. In contrast, neither dislocations nor stacking faults were observed in LaNi 4.5Si 0.5, LaNi 4.5Al 0.5 and LaNi 4.75Sn 0.75, which showed little or no hysteresis in the hydrogen pressure–composition isotherms. Excess pressure was needed in the absorption process for the formation of misfit dislocations.

Effect of La-content on the hydrogenation properties of the Ce1−xLaxNi3Cr2 (x=0.2, 0.4, 0.6, 0.8, 1) alloys

The effect of partial substitution of Ce by La in CeNi3Cr2 hydrogen storage alloy has been systematically investigated. All intermetallic compounds Ce1-xLaxNi3Cr2 (x = 0.2, 0.4, 0.6, 0.8, 1) synthesized by arc melting method are well characterized by the means of XRD and SEM. XRD results show that all the alloys are crystallized as a single-phase compound in the hexagonal CaCu5 type structure. The substitution of Ce by La leads to increase the unit cell volume of the alloy. Hydrogen storage capacity has been investigated in the temperature and pressure range of 293K ≤ T ≤ 323 K and 0.5 ≤ P ≤ 45 bar respectively using pressure-composition isotherm. The P-C isotherm curves show that the plateau pressure of the hydrogen absorption decreases and hydrogen storage capacity increases with increasing La content in the alloy. The enthalpy (∆H) and entropy (∆S) of dissolved hydrogen for all systems has been calculated using Van’t Hoff plot. The variation of ∆H and ∆S with hydrogen content has also been studied which confirm the phase boundaries.

Structure and Thermodynamic Properties of the NaMgH3 Perovskite: A Comprehensive Study

One of the bottlenecks in the implementation of a hydrogen economy is the development of storage materials that can uptake high content of H2 and release it within a suitable temperature and pressure range. Among the proposed hydride systems, the perovskite NaMgH3 is receiving increasing attention, not only as the Mg ternary based hydride with the highest hydrogen gravimetric (6 wt %) and volumetric density (88 g L−1) but also as a stable hydride likely to be formed in the transformation reactions of mixed hydrides. However, there is a large scatter in the literature for both the structure of the NaMgH3 compound and the thermodynamics of the hydrogenation/dehydrogenation processes. In this paper a critical review of the literature data, supported by a new set of experimental (in situ synchrotron X-ray diffraction, infrared spectroscopy, high-pressure differential scanning calorimetry, pressure composition isotherms) and theoretical data is presented. The influence of ball milling on the microstructure is studied in the NaMgH3 in comparison to NaH and MgH2. The infrared spectrum of NaMgH3 compound, assigned by calculated and experimental results, is characterized by vibrational regions around 1100 and 600 cm−1. In situ synchrotron X-ray diffraction measurements show the desorption reaction of NaMgH3 into NaH and Mg at about 673 K under 0.2 MPa H2, and the successive reabsorption of NaH and Mg back to NaMgH3 at 623 K under 0.5 MPa H2. From high-pressure differential calorimetry, it was measured a formation enthalpy of 141 kJ/mol f.u for NaMgH3 compound. It was confirmed the possible reaction of NaH with Mg with observation of NaMgH3 formation in 1.0 MPa H2. Finally, this work provides a thermodynamic description of the NaMgH3 phase by a critical assessment of the available information using the CALPHAD approach and the equilibrium pressure−temperature phase diagram is presented.

Effects of annealing treatment and partial substitution of Cu for Co on phase composition and hydrogen storage performance of La 0.7Mg 0.3Ni 3.2Co 0.35 alloy

In this paper, the phase composition, hydrogen absorption/desorption as well as electrochemical characteristics of as-cast and annealed La 0.7Mg 0.3Ni 3.2Co 0.35− X Cu X alloys were investigated by X-ray diffraction (XRD), pressure composition isotherm (PCT) and electrochemical measurements. The results showed that La 2Ni 7 phase and LaNi phase coexisted in the as-cast alloys, but only La 0.98Ni 5.10 phase was detected in the annealed alloys. The maximum and reversible hydrogen storage capacities of the annealed alloys were higher than that of as-cast alloys, with greatly improved plateau performance. The substitution of Cu for Co made the electrochemical discharge capacity of the annealed alloys lower than that of as-cast alloys.

Hydrogen insertion in Pd core/Pt shell cubo-octahedral nanoparticles

We report a theoretical density functional theory study of the absorption and adsorption of hydrogen in Pd core/Pt shell cubo-octahedral nanoparticles of 55 and 147 atoms. We have explored all the possible sites available for hydrogen loading. The relative stability of H in the different sites is calculated and discussed in terms of the local geometrical and chemical environments. As a general trend, the most stable absorption sites are pyramidal interstices at the interface offering a volume for H around 2 × 2.60 A3, with a moderate atomic rearrangement upon H insertion and in which the H atom maximizes the number of Pd neighbors. Our theoretical findings give support to the recent hydrogen pressure-composition isotherms and NMR measurements carried out in this type of bimetallic nanoparticle [Kobayashi et al., J. Am. Chem. Soc. 130, 1818 (2008)].

Phase transition and hydrogen storage properties of melt-spun Mg 3LaNi 0.1 alloy

Nominal Mg 3LaNi 0.1 alloy was prepared by a single roller melt-spun method. The phase structure and hydrogen storage properties of the obtained ribbons were studied by X-Ray diffraction (XRD), transmission electron microscopy (TEM), differential scanning calorimetry (DSC) analysis and pressure-composition isotherm (PCI) measurements. The melt-spun Mg 3LaNi 0.1 alloy was composed of Mg 3La phase, while fine LaMg 2Ni grains were precipitated after an aging treatment at room temperature. Both Mg 3La and LaMg 2Ni undertook disproportion reactions upon hydrogenation and decomposed into MgH 2, LaH 3 and Mg 2NiH 4. The melt-spun alloy shows excellent hydrogen absorption kinetics and lowered desorption temperature comparing with the induction-melted alloy, and a maximum hydrogen storage capacity of 3.1 wt.% and a minimum hydrogen desorption temperature of 224 °C were achieved. This improvement on the hydrogen storage properties was attributed to the catalytic role of in-situ formed nanocrystalline Mg 2Ni and LaH 2.

Hydrogenation properties of shape memory Ti(Ni,Pd) compounds

The effect of Pd substitution on the crystal structure and hydrogenation properties of TiNi compound has been investigated. Ti(Ni,Pd) are pseudo-binary compounds. The unit-cell volumes of B2 (Austenite) and B19 (Martensite) structures linearly increase with Pd substitution in Ti 1.04Ni 0.96− x Pd x samples. The hydrogenation properties of Pd-substituting Ti(Ni,Pd) compounds are not affected by the crystal structure of the parent compounds. For all samples, hydrogen absorption occurs without showing any clear plateau pressure in Pressure-Composition-Isotherm (PCI) curves. All hydrided samples crystallise in the tetragonal I 4/ mmm space group. At 6 MPa of hydrogen pressure and T = 423 K, the hydrogenation capacity of Ti(Ni,Pd) compounds reaches 1.52 hydrogen atoms per formula unit (H/f.u.) for x = 0.1 and then gradually decreases with Pd content down to 0.93 H/f.u. for x = 0.5. Ti 1.04Ni 0.86Pd 0.10 sample yields a discharge capacity of 148 mAh/g at C/5 regime when used as negative electrode in Ni-MH battery. The hydrogenation properties of Pd-substituting Ti(Ni,Pd) compounds are discussed in detail by comparison with previous studies on Zr substituting, (Ti,Zr)Ni compounds.

Enhanced hydrogen storage performance of LiAlH 4–MgH 2–TiF 3 composite

The mutual destabilization of LiAlH 4 and MgH 2 in the reactive hydride composite LiAlH 4–MgH 2 is attributed to the formation of intermediate compounds, including Li–Mg and Mg–Al alloys, upon dehydrogenation. TiF 3 was doped into the composite for promoting this interaction and thus enhancing the hydrogen sorption properties. Experimental analysis on the LiAlH 4–MgH 2–TiF 3 composite was performed via temperature-programmed desorption (TPD), differential scanning calorimetry (DSC), isothermal sorption, pressure-composition isotherms (PCI), and powder X-ray diffraction (XRD). For LiAlH 4–MgH 2–TiF 3 composite (mole ratio 1:1:0.05), the dehydrogenation temperature range starts from about 60 °C, which is 100 °C lower than for LiAlH 4–MgH 2. At 300 °C, the LiAlH 4–MgH 2–TiF 3 composite can desorb 2.48 wt% hydrogen in 10 min during its second stage dehydrogenation, corresponding to the decomposition of MgH 2. In contrast, 20 min was required for the LiAlH 4–MgH 2 sample to release so much hydrogen capacity under the same conditions. The hydrogen absorption properties of the LiAlH 4–MgH 2–TiF 3 composite were also improved significantly as compared to the LiAlH 4–MgH 2 composite. A hydrogen absorption capacity of 2.68 wt% under 300 °C and 20 atm H 2 pressure was reached after 5 min in the LiAlH 4–MgH 2–TiF 3 composite, which is larger than that of LiAlH 4–MgH 2 (1.75 wt%). XRD results show that the MgH 2 and LiH were reformed after rehydrogenation.

Structural and H2 sorption properties of MgH2–10 wt%ZrCrM (M = Cu, Ni) nano-composites

Magnesium and its hydride MgH2 are widely regarded as promising candidates for hydrogen storage materials due to its benefits of high gravimetric and volumetric capacity, excellent reversibility, abundance in the earth and a low cost. Much attention has been paid to improve its absorption/desorption kinetics, trying to make it useful for practical applications. To make composite of MgH2 with other hydrogen storage compounds is an effective method to improve the hydrogen storage properties. In this study nano-composite of MgH2 with ZrCrCu alloy was prepared using high energy ball-milling for 5 h under Ar atmosphere. Microstructure and morphology of the composites were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM). XRD patterns show that no alloy formation between MgH2 and elements of the alloys takes place during milling. Different morphology of the powders as-milled and after cycling was observed by SEM. Pressure–composition isotherms of these composites have been obtained in the pressure range 0.1–10 bar at 275 and 300 °C. The absorption/desorption kinetics data have been analyzed using pressure 0.1–5.0 bar at 275 and 300 °C to understand the mechanism of the hydriding/dehydriding reaction processes. A comparison of these results has been attempted with our previous published results of MgH2–10 wt%ZrCrNi in order to find the better composite for storage applications. It is observed by DSC curves that the onset temperature of hydrogen desorption is decreased for MgH2–10%ZrCrNi in comparison to MgH2 which further decreased for MgH2–10%ZrCrCu. However, little loss in hydrogen absorption/desorption capacity is also observed for ZrCrCu composite in comparison to that of ZrCrNi composite.