Hydrogen Absorption Performance Research Articles

Investigation on the hydrogen absorption and dissociation properties of ball milling CeMg12/Ni/NbF5 type alloy for emergency power supply of fuel cell for meteorological radar station

In this article, in order to investigate the mechanism of action of catalysis on the hydrogenation and dehydrogenation properties of CeMg12-type alloy, the catalysis Ni and NbF5 was been added to prepare the CeMg12/Ni/NbF5 composite materials during ball milling treatment. The results in term of microstructure indicate that part of NbF5 is transformed into low valence NbF4 and helpful for forming MgF2 phase after ball milling treatment, which is advantageous for ameliorating the hydriding and dehydriding performances of experimental alloy. The results of the study from the perspective of hydrogen absorption and desorption performance test show that the increasing NbF5 decreases the enthalpy-value for hydrogen release and the platform pressure for the process of hydrogen releasing of ball-milled alloy, which is good for improving the hydrogen release performance of the alloy. The addition of a certain amount of NbF5 can effectively upgrade the kinetics of hydrogen dissociation of CeMg12-type alloy treated through mechanical ball milling. The alloy with 6 wt.% NbF5 has the best kinetic performance of hydrogen release, corresponding to activation energy can be reduced from 90.86 kJ/mol (0 wt.% NbF5) to 86.41 kJ/mol(6 wt.% NbF5).

Effect of partition arrangement of metal hydrides and phase change materials on hydrogen absorption performance in the metal hydride reactor

Metal hydride (MH) suffers from strong thermal effects during hydrogen absorption. To fully utilize the reaction heat during hydrogen absorption, phase change material (PCM) can be used to achieve efficient thermal management in the reactor. A novel MH-PCM reactor with the partition arrangement of MH and PCM was proposed in this paper. Then, the two-dimensional multiphysics coupled model of the reactor was developed, and the effects of the number of partitions n, the mass of PCM and the hydrogen absorption pressure Pa on the hydrogen absorption performance were discussed detailedly. The results indicated that the novel MH-PCM reactor not only increases the heat transfer area and boots the hydrogen absorption rate, but also improves the uniformity of temperature distribution. As the n increases from 2 to 5, the hydrogen absorption time gradually shortens. Compared to the conventional MH-PCM reactor, the time for 90% hydrogen absorption shortens by 67.13%. Furthermore, the hydrogen absorption rate can be enhanced with the increasing mass of PCM and Pa. However, the larger these values are, the weaker the enhancement effect becomes. The results of this paper may provide a new direction for the optimized design and engineering application of MH-PCM reactors.

Study on hydrogen absorption performance of the modified Zr/ZrVFe porous getters

Non-evaporable getter is used to remove active gases in sealed-off vacuum devices, especially H2 at room temperature. In this work, Zr/ZrVFe getters with different Zr content (0, 30 and 50 %) were fabricated using vacuum sintering method, then futher improvement of pumping properties had been explored with Ni overlayer as deposited on the surfaces of Zr/ZrVFe getter by magnetron sputtering technique. Subsequently, residual gas and pressure change during the activation process of Zr/ZrVFe getters were measured. It was found that when the activation temperature reached 350 °C, the desorption of impurity gases was basically completed, there was only H2 in the system. Moreover, the hydrogen absorption properties of the Zr/ZrVFe getters modified by Zr content and Ni overlayer were examined. Results indicated that the sintered ZrVFe getter with 0 % Zr content had a large number of cracks and occurred the phenomenon of falling powder, Zr30 %/ZrVFe getter had better hydrogen absorption properties in comparison with Zr50 %/ZrVFe getter owing to the larger porosity and specific surface area. Ni had the catalytic characteristics of decomposing molecular hydrogen into hydrogen atoms and Ni film was uniformly covered on the getter surface, the hydrogen absorption properties of Zr/ZrVFe getter with Ni overlayer were significantly improved.

Influence of corrugated tube structure and flow rate on the hydrogen absorption performance of metal hydride reactor and structural optimization

The metal hydride bed (MHB) reactor is an effective instrument for storing hydrogen. However, thermal stress causes the cooling tube expansion inside the MHB. The long-term effects will lead to the failure of the cooling tube. To absorb the thermal stress and reduce the deformation of the cooling tubes, this article establishes an MHB reactor with corrugated cooling tubes to study its hydrogen absorption performance. The results prove that some parameters are adversarial and flow rate patterns are complex (such as extreme flow rate and insufficient flow rate) in the hydrogen absorption process of the corrugated tube MHB reactor, which makes it impossible to optimize the structure of the corrugated tube through the gradient method. Under the condition of a fixed corrugated tube volume of 3×10−6m3 and a cooling water volumetric flow rate of 0.5×10−4m3/s, the structural parameters of the corrugated tube are optimized by the Monte Carlo algorithm. According to the optimized results (N=8, ro=4.25 mm, ri=3.98 mm, do=3.17 mm, di=4.33 mm), the hydrogen absorption efficiency of the corrugated tube MHB reactor (reaction fraction 0.758) is 1.36 times that of the straight tube (reaction fraction 0.557) at 560 s. Thus, the corrugated tube can reduce thermal stress and improve the heat transfer effect. This research is beneficial in improving long-term stability, enhancing operational efficiency, and reducing the volume and weight of large MHB reactors.

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.

Porous Silicone Rubber Composite Supported 1,4-Diphenylethynyl Benzene for Hydrogen Absorption with Pd/C Catalyst.

Hydrogen is a dangerous gas as it reacts very easily with oxygen and may explode; therefore, the accumulation of hydrogen in confined spaces is a safety hazard. Composites consisting of unsaturated polymers and catalysts are a common getter, where the commonly used polymer is 1,4- diphenylethynyl benzene (DEB). Silicone rubber (SR) is a good carrier for hydrogen-absorbing materials due to its excellent chemical stability and gas permeability. In this work, polysiloxane, water, and a emulsifier are ultrasonically injected into a uniform emulsion, and the hydrogen getter DEB-Pd/C (Palladium on carbon) is then added. Under the catalysis of platinum (Pt), the cross-linking agent undergoes a hydrosilylation reaction to cross-link polysiloxane in emulsion to form silicone rubber. Then, the water was removed by freeze-drying, and the loss of water constructed a porous frame structure for silicone rubber, thus obtaining porous silicone rubber. The difference in hydrogen absorption performance between porous silicone rubber and ordinary silicone rubber was compared. It was found that, with the increase in water in the emulsion, the porous frame of silicone rubber was gradually improved, and the hydrogen absorption performance was improved by 243.4% at the highest, almost reaching the theoretical saturated hydrogen absorption capacity. Porous silicone rubber was prepared by emulsion mixing, which provided a new idea for further improving the hydrogen absorption performance of silicone rubber.

The relationship between thermal management methods and hydrogen storage performance of the metal hydride tank

Solid-state hydrogen storage tanks are key equipment for fuel cell vehicles and hydrogen storage. However, the low heat transfer properties of hydrogen storage tanks result in the inability to meet the hydrogen supply requirements of fuel cells. In this study, different thermal management approaches were explored through the design of LaNi5-based solid-state hydrogen storage tanks. We experimentally studied the effects of different internal heat transfer methods, that is, expanded natural graphite (ENG), copper foam, and copper fins on the hydrogen absorption and desorption performance. We also studied the effects of external cooling methods with natural convection, air cooling, and water cooling, respectively. Under the same external cooling method of natural convection, a solid hydrogen storage tank filled with 5 wt.% ENG has similar performance to a tank filled with copper foam. Compared to natural convection, air and water cooling can significantly improve the heating performance of metal hydride (MH) beds by increasing the external heat transfer coefficient. The effect of water cooling is better than that of air cooling, and in these two enhanced performance conditions, the tank filled with copper foam performs better than with ENG. In the case of water cooling, by adding copper fins to a hydrogen storage tank filled with 5 wt.% ENG, the tank was saturated with hydrogen absorption in only 29.4 min, which is 55.6 % shorter than the hydrogen uptake time in a hydrogen storage reactor without copper fins. And its stable hydrogen desorption (1 NL/min) has reached 98.1 % of the total hydrogen released. The results show that the effective thermal conductivity and heat transfer area of metal hydride bed play key roles in improving heat transfer and reaction rate. In addition, heat transfer is more important than mass transfer to improve the performance of the hydrogen storage tank.

Effects of differential speed rolling and H2S poison on hydrogen storage performance of ZK60 alloys ball-milled with C, Pd, Ag, and Zr

The commercial ZK60 magnesium alloy was used to investigate hydrogen absorption performance. The ZK60 alloy was severely deformed via differential speed rolling with differential speeds of 6:3 and 9:3. High energy ball milling was used to blend deformed ZK60 powder with 5 wt% activated carbon(C), 0.5 wt% silver (Ag), 0.5 wt%palladium (Pd), and 1 wt% zirconium (Zr) for 20h at 1725 rpm. Hydrogen absorption characteristics at different low temperatures and number of cycles were analyzed using Sievert's apparatus with hydrogen supplied with H2S impurities. The microstructure of the powder was analyzed field emission scanning electron microscope (FESEM). The hydrogen absorption capacity increases with the temperature rise, and maximum capacity(6.02 wt%) was observed in 5C1Zr deformed at 9:3DSR at 200 °C after five cycles. Hydrogen absorption capacity increases after each hydrogenation cycle in 5C0.5Ag and 5C1Zr but remains the same in 5C0.5Pd. The increase in H2S concentration decreases the hydrogen capacity, and increase in the number of cycles further deteriorates absorption capacity when the differential speed ratio is 6:3. The H2S concentration variation has almost no effect at the differential speed of 9:3. The maximum hydrogen absorption kinetics (74.7%) in 10min was observed in 5C1Zr. A more refined dendritic microstructure was observed in ZK60 alloy deformed with a differential speed ratio of 9:3.

Effects of Cu on the microstructure and hydrogen storage properties of Mg-20Ni alloy

In order to improve the hydrogen storage capacity of hypereutectic Mg-Ni alloy, the Mg40Ni10 and Mg40Ni8Cu2 alloys were prepared by metallurgy method. The effects of Cu on the alloys’ phase composition, microstructure were studied systematically. The volumetric Sieverts’ method was used to test and analyze the activation performance and hydrogen absorption and desorption kinetic performance of the alloys. It was found that the partial substation of Ni in the Mg2Ni-riched matrix alloy with Cu can change the primary Mg2Ni and eutectic Mg-Mg2Ni morphology of the alloy. With the doping of Cu content, although the activation property of the alloy decreases, the hydrogen storage capacity as well as the kinetic of hydrogen absorption and desorption are improved significantly.

The synergistic effect of Ni and C14 Laves phase on the hydrogen storage properties of TiVZrNbNi high entropy hydrogen storage alloy

As a hydrogen storage alloy, the body-centered cubic (BCC) structure has been well studied due to its large hydrogen storage capacity. On this basis, the introduction of catalytic elements and an appropriate amount of C14 Laves phase can further improve the comprehensive hydrogen storage properties of hydrogen storage alloys. Based on this theory, (Ti32.5V27.5Zr7.5Nb32.5) 1-xNix (x = 0.03, 0.06, 0.09) high entropy hydrogen storage alloys with an appropriate amount of catalytic element Ni are prepared in this study. The raise in Ni content is accompanied by grain refinement of the dendritic structure, an increase in the number of grains and grain boundaries, and a gradual increase in the proportion of C14 Laves phase. The introduction of catalytic element Ni reduces the dissociation energy of hydrogen molecules. The increasing grain and grain boundaries increase more hydrogen absorption sites with lower activation energy. The diffusion channel provided by the appropriate amount of C14 Laves phase makes it easier for hydrogen atoms to diffuse into the main phase BCC phase with strong hydrogen absorption capacity, and the hydrogen atoms are trapped by vacancy defects with large hydrogen binding energy. The synergistic effect of the three factors ensures the improvement of hydrogen absorption performance of high entropy hydrogen storage alloys. (Ti32.5V27.5Zr7.5Nb32.5) 0.94Ni0.09 high entropy hydrogen storage alloy achieves excellent saturated hydrogen storage capacity of 2.78 wt % and 2.99 wt % at room temperature and 150 °C under 3 MPa hydrogen pressure, respectively. In addition, the introduction of Ni element reduces the thermal stability of metal hydrides, thereby improving the dehydrogenation performance of high entropy hydrogen storage alloys. The reversible phase transition occurs during the whole hydrogen absorption and desorption cycle.

Phase distributions in YB3 alloys (B[dbnd]Cr, Mn, Fe, Co, Ni, Cu) and related hydrogen storage performances

The phase distributions and hydrogen absorption and desorption performances for YB3-type alloys were investigated in the paper. The compositions of the alloys can be generally divided into three categories, and the pure metal phase will disappear gradually with the increase of B-side atomic number in the YB3 alloys. The hydrogen storage capacity and desorption rate increase first, and then decrease with the atomic number. The dehydrogenation temperatures and the molar enthalpies of the hydrides during the desorption process are also discussed.

Thermodynamics and kinetics hydrogen isotope effects of hydrogen/deuterium absorption in Pd-5wt.%Pt alloy

Palladium–Platinum (Pd–Pt) alloys have excellent hydrogen isotope separation properties near room temperature compared to pure palladium (Pd), and are expected to be used as filling materials in thermal cyclic absorption (TCAP) columns. However, most studies on the thermodynamic and kinetic hydrogen isotope effects of hydrogen absorption/deuterium in Pd–Pt alloys have been conducted at temperatures of 273 K or above, with few studies involving the performance of TCAP in the cold-cycle operating temperature range (253 K–303 K). In this work, the performance of Pd-5wt.%Pt alloy for the absorption of hydrogen/deuterium at low temperatures (263 K–323 K) was investigated. The results show that the enthalpy and entropy of dissolution of hydrogen and deuterium in the α-phase of Pd-5wt.%Pt alloy are −11.77 kJ/mol (H), 104.00 J mol−1 K−1(H); −5.50 kJ/mol (D), 87.88 J mol−1 K−1 (D), respectively, which are lower than the enthalpy and entropy change values of pure Pd materials. The apparent reaction activation energies of protium and deuterium absorption are −4.14 kJ/mol (H2) and −11.87 kJ/mol (D2), respectively, which are lower than those of pure palladium. The excellent hydrogen isotope separation performance of Pd–Pt alloys may originate from the fast hydrogen absorption and discharge isotope kinetic performance.

Numerical study on storage performance of metal hydride reactors with multiple spiral fins

Metal hydride (MH) is an efficient hydrogen storage method with high density and moderate operating conditions. Thermal management is required for hydrogen storage and release to cope with the strong thermal effects generated by the reaction. The MH reactor with spiral fins is proposed to improve the hydrogen storage efficiency by increasing the heat transfer characteristics of the reactor. The hydrogen absorption and desorption performances of the MH reactors with different spiral fin structures have been discussed. The results show that the MH reactor with spiral fins present better reaction performance compared to that of the MH reactor with longitudinal fins. And the larger the fin spiral cycle (SC), the faster the reaction rate. The hydrogenation time and dehydrogenation time could be maximally reduced 29.8% and 29.2% with fin spiral cycle increasing from 1/4 to 1, where the hydrogen storage density kept constant. The hydrogenation time and dehydrogenation time could be reduced 53.1% and 34.7% with fin number (FN) increasing from 4 to 16, while the hydrogen storage density is reduced 24.1%. Keep the volume of fins consistent, the fin number and fin thickness (FT) are optimized, and the results are FN = 8, SC = 1, FT = 1 mm, the corresponding hydrogen storage density is 0.087 g mm−1. The performance of the reactor with the optimal fin parameters under different operation conditions was also analyzed. The recommended operation parameters are concluded as the hydrogen pressure of 1.0 MPa for absorption and 0.1 MPa for desorption, heat transfer wall temperature of 293.15 K for absorption and 353.15 K for desorption.

Channel role of nano-Mg2Ni in enhancing hydrogen absorption and desorption performances in Mg/Mg2Ni system

Mg2Ni is considered as a promising material for both storage hydrogen and catalyze MgH2 decomposition. Using Mg2Ni–Mg as a matrix material may achieve the combination of both advantages. Herein, hypoeutectic and hypereutectic Mg100-xNix (x = 11, 15, 22) alloys are prepared in this work to investigate the relationship between Mg2Ni in different microstructures and hydrogen storage performances. The results indicate that Mg2Ni connected Mg–Mg2Ni eutectics are formed besides the lamellar eutectic in Mg85Ni15 and Mg78Ni22 alloys because Mg2Ni precipitates firstly in eutectics, which are different from the α-Mg connected Mg–Mg2Ni eutectics in Mg89Ni11 alloy. Mg100-xNix alloys show rapid hydrogen absorption rates at ranges of both 125–175 °C and 275–325 °C because the presents of abundant interfaces generated by nano-Mg2Ni particles. Mg89Ni11 alloy with hydrogenation capacities of 3.6 wt% at 125 °C due to the large hydrogenation driving force of α-Mg. The Mg78Ni22 hydride with the highest proportion nano-Mg2Ni phase presents the fastest dehydrogenation rates. Two independent decomposition peaks are observed in the DSC curves of Mg100-xNix hydrides and the desorption temperature of Mg2NiH4 becomes lower with increasing Mg2Ni content due to Mg2Ni nanoparticles providing channels for the rapid diffusion of H atoms, and the reduced H concentration is conducive to the decomposition of MgH2.

Microstructure and hydrogen storage properties of Zr-based AB2-type high entropy alloys

This paper reports the partial substitution of Fe, Co, Ni and Cu for Mn in ZrMnCr0.5V0.5 alloy with to obtain ZrMn0.5Cr0.5V0.5M0.5 (M = Fe, Co, Ni and Cu) high entropy alloys. These alloy samples are prepared by electric arc melting, and their microstructure and hydrogen storage properties are investigated in detail. Structural analysis results show that all the five alloys consist of C14 type Laves primary phase. Metastable cubic phase can be observed in ZrMnCr0.5V0.5 and Fe-, Co-substituted alloys, while ZrNi, Cu10Zr7 and Cu8Zr3 phase secondary phases exist in Ni- and Cu-substituted alloys. Hydrogen storage testing results show that elemental substitution greatly improves the first activation properties of the alloys. All the five alloys can absorb hydrogen rapidly when the temperature is above 100 ℃, while the elemental substitution significantly affects the hydrogen absorption kinetics at lower temperatures. Compared with other four alloys, the Cu-substituted alloy has two kinds of Cu-Zr secondary phases, resulting in a poorer hydrogen absorption performance. Pressure-composition isotherms (P-C-T) test results show that all these alloys have very sloping absorption and desorption plateaus. It is also found that all the alloy particles are pulverized spontaneously during hydrogenation cycles, but there is no clearly change on phase structure of C14 type Laves phase, and the alloys show a good cycling performance. Among these alloys, the ZrMn0.5Cr0.5V0.5Fe0.5 alloy has the best hydrogen storage performance because it has the shortest activation time and fast hydrogen absorption at room temperatures.

Influencing mechanism of carbon monoxide on the hydrogen absorption performance of Zr2Fe

Zr2Fe is considered as the promising hydrogen isotopes trapping material to control the quantity of tritium generated in deuterium–tritium fusion reaction. However, the vulnerability to poisoning by impurity gases such as carbon monoxide is the bottleneck for their applications. In this study, we show from our DFT calculations that the Zr2Fe(101) surface is saturated with 13CO molecules and the hollow site is the most stable CO adsorption site. The adsorption energy of CO is much lower than that of hydrogen, resulting in the preferential adsorption of CO on Zr2Fe(101). The dependence of the Gibbs free energies of CO on the temperatures under UHV conditions were also obtained. The climbing-image nudged elastic band results reveal that CO pre-coverage would block the hydrogen adsorption sites and affect the hydrogen diffusion. The Sieverts analysis demonstrates that even the low concentration CO is a fatal poison to the hydrogenation process of Zr2Fe at ambient temperature. Hydrogen absorption may occur at a higher temperature with a lower absorption rate and capacity, as CO starts to desorpt from Zr2Fe(101) with the increase of temperature and thus making H2 absorption possible, even though the H diffusion energy barriers are relatively high. Our results provide the basis for exploring the influence mechanisms of the impurity gas CO on the hydrogen adsorption properties of the Zr-based alloys, which would be beneficial for the applications of metal getter of tritium-containing waste gas.

Hydrogen Absorption Performance and O2 Poisoning Resistance of Pd/ZrCo Composite Film.

In order to enhance the hydrogen absorption performance and poisoning resistance of ZrCo to O2, Pd/ZrCo composite films were prepared by direct current magnetron sputtering. The results show that the initial hydrogen absorption rate of the Pd/ZrCo composite film increased significantly due to the catalytic effect of Pd compared with the ZrCo film. In addition, the hydrogen absorption properties of Pd/ZrCo and ZrCo were tested in poisoned hydrogen mixed with 1000 ppm O2 at 10-300 °C, where the Pd/ZrCo films maintained a better resistance to O2 poisoning below 100 °C. The mechanism of poisoning was investigated jointly by first-principles calculation combined with SEM-EDS elemental mapping tests. It is shown that the poisoned Pd layer maintained the ability to promote the decomposition of H2 into hydrogen atoms and their rapid transfer to ZrCo.

Improvement in hydrogen storage performance of Mg by mechanical grinding with molten salt etching Ti3C2Clx

Mg-based materials are currently a hot research topic as hydrogen storage materials due to their considerable theoretical hydrogen storage capacity. However, the kinetic performance of hydrogen absorption and desorption of Mg is too slow and requires high temperature, which seriously hinders the application of this material. MXene is a new type of two-dimensional material with significant role in improving thermodynamics and kinetics. In this experiment, a two-dimensional layered MXene containing Cl functional group was prepared by molten salt etching using the Ti-containing MAX phase as the raw material. Then different ratios of Ti3C2Clx were uniformly dispersed onto the surface of Mg by high energy ball milling. The samples were characterized by hydrogen absorption and desorption kinetics, SEM, XRD, XPS, and DSC to investigate the effect of Ti3C2Clx on the hydrogen absorption and desorption performance of Mg. The onset hydrogen absorption temperature can be reduced to room temperature and the hydrogen release temperature is reduced by 200 ​°C by doping Ti3C2Clx. And there is also 5.4 ​wt% hydrogen storage in the isothermal hydrogen absorption test at 400 ​°C. The results of DSC demonstrate that the Ea of Mg+15 ​wt% Ti3C2Clx was reduced by 12.6% compared to pristine Mg. The ΔH is almost invariable. The results of XPS show that the presence of multivalent Ti promotes electron transfer and thus improves the conversion between Mg2+/Mg and H−/H. This study provides a guideline for further improving the hydrogen absorption and desorption performance of Mg-based hydrogen storage materials.

Effect of low concentration of impurity gases on the hydrogen absorption performance of uranium

The performance of uranium as a hydrogen storage material has attracted much attention. Herein, the hydrogen absorption properties of depleted uranium in impure hydrogen containing He, Ar, CH4, N2, CO, CO2 and O2 were studied by PVT method and XPS analysis. When these impurity gases were mixed in H2 at low concentrations (0.1%∼1.5%), their behavior can be classified into three categories. The He, CH4 and Ar were chemically inert to the activated uranium powder under room condition. These three gases inhibited the absorption kinetics during the whole stage by hindering the diffusion of H2 molecules, showing a blanketing effect. The N2 and O2 did not affect the absorption kinetics but reduced the capacity by forming nitrides and oxides. The poisoning effect of N2 was weaker than that of O2. The CO and CO2 not only affected the hydrogen absorption capacity, but also strongly inhibited the absorption kinetics. These two gases are chemically adsorbed on the uranium surface to form passivation layers, thus inhibiting the adsorption and dissociation of H2 molecules and the diffusion of H atoms. The poisoning and retardation effect of CO2 were much stronger than that of CO. The above conclusions are important to further study the reactivity of mixed gas with uranium, and can also be used as a reference for other hydrogen storage systems.

Micro-mechanism study on the effect of O2 poisoned ZrCo surface on hydrogen absorption performance

Hydrogen storage alloys are usually susceptible to poisoning by O2, CO, CO2, etc., which decreases the hydrogen storage property sharply. In this paper, the adsorption characteristics of oxygen on the ZrCo(110) surface were investigated, and the effect of oxygen occupying an active site on the surface on the hydrogen adsorption behavior was discussed. The results show that the dissociation barrier of H2 is increased by more than 26% after O occupies the active sites on the ZrCo(110) surface, and the probability of H2 adsorption and dissociation decreases significantly. The adsorption energy of H atoms on the O–ZrCo(110) surface decreased by 18–56%, and the adsorption stability of H decreased. In addition, H atom diffusion on the surface and into bulk are prevented with higher reaction energetic barriers by O occupying active sites. Eventually, the ability of the ZrCo surface to adsorb hydrogen is seriously reduced.