ZrCo Alloy Research Articles

Self-sacrificial hydrogen channel enhances the poisoning resistance of ZrCo-based alloy

ZrCo alloy is considered as a promising candidate for hydrogen isotope storage in nuclear fusion reactors. However, severe poisoning caused by the impurities contained in hydrogen is an inevitable issue in engineering applications. Herein, the effects of Cr-doped ZrCo with segregated the reticular ZrCr2 phase on the activation and oxidation resistance were investigated systematically. Experimental results show ZrCo0·95Cr0.05 can achieve 1.71 wt% hydriding capacity within about 37 min under 1 mol% O2 + 99 mol% H2, whereas ZrCo consumes more than 4 times (150 min) to reach the same capacity. Specifically, the improved anti-poisoning ability of the ZrCo–Cr system could be attributed to the three-step chain effect induced by Cr doping, including the hydrogenation-prone and oxygen resistance character of ZrCr2 phases, sacrificial and catalysis of in-situ formed metallic Cr clusters, and protective effects of Cr oxide layers. Hence, the active sites for rapid hydrogen absorption were obtained and inferior oxygen resistance of ZrCo substrates was alleviated through the self-sacrifice of ZrCr2 and Cr. This work not only proves the feasibility of the multi-component alloying strategy in the field of ZrCo alloy anti-poisoning modification, but also reveals that the core of the multi-component alloying strategy is to realize the modulation of the microstructure through the composition design.

The thermodynamic properties of ZrCo hydrogen isotopes storage: The effect of Ta doping

ZrCo alloy exhibits distinct advantages in the storage of hydrogen and its isotopes. In this study, the phonon dispersion relation of ZrCo and ZrCoMx (M = H, D, T) is calculated. Subsequently, the thermodynamic properties of ZrCo and ZrCoMx compounds are investigated. Furthermore, an analysis is conducted on the temperature-dependent variations in the thermodynamic properties during hydrogen (deuterium, tritium) absorption reactions. Additionally, the impact of Ta doping (Zr0·875Ta0·125Co) on the thermodynamics of hydrogen storage (deuterium tritium) in ZrCo is discussed. The results indicate that H in the octahedral void leads to a higher thermodynamic value and a more stable system compared to H in the tetrahedral interstice. When ZrCo alloy store deuterium and tritium, there is an increase in ZPE, △H and △G of the system. At 300 K, the △H of ZrCo reacting with hydrogen, deuterium and tritium to form ZrCoM3 (M = H, D and T) are 85.94 kJ/mol, 90.09 kJ/mol and 92.16 kJ/mol, respectively. The ZPE and the △H of reaction are reduced upon Ta doping, thereby facilitating hydrogen (deuterium and tritium) circulating storage capabilities of alloy.

First-principles investigation on the effect of Nb and Ta doping on the hydrogen storage performance of ZrCo

The ZrCo alloy has demonstrated significant potential in the storage of hydrogen and its isotopes, but there are still some issues such as insufficient dynamic properties. In this paper, the impact of Nb/Ta doping on the hydride stability of ZrCo was examined based on the density functional theory, and the improvement of H diffusion through Nb/Ta doping was investigated. The focal point lies in exploring the influence of Nb/Ta doping on the alloy’s resistance to poisoning and disproportionation. The results demonstrate that the crystal lattice maintains mechanical and thermodynamic stability even after Nb/Ta doping. Nb/Ta doping induces lattice contraction in ZrCo-Hx (x = 1.0–3.0) and reduce the enthalpy of formation, thereby facilitating cyclic hydrogen storage. Additionally, Nb/Ta doping enhances the diffusion performance of H atoms within O-containing lattice, improving the alloy’s resistance to poisoning. Furthermore, Nb/Ta doping lowers the energy barrier of H atoms escape from 8e sites, promoting anti-disproportionation.

Influence of Hf Doping on the Oxygen Behaviors on ZrCo(110) Surface Using First-Principles Calculation

ZrCo alloy is easily poisoned by impurity gases such as O2, CO, and CO2, resulting in a deterioration in hydrogen storage performance. In this study, we conducted a comprehensive investigation into the adsorption and dissociation characteristics of oxygen on the ZrCo(110) surface using first-principles calculations. Previous studies indicated that the anti-disproportionation properties of ZrCo alloy can be significantly improved by Hf substitution, but the effect of Hf doping on the anti-poisoning properties has not been reported. We also examined the effect of Hf doping on the adsorption, dissociation, and diffusion characteristics of oxygen. It is found that on the ZrCo(110) surface, O2 molecules are easily dissociated and then stably adsorbed at the hollow site. Oxygen atoms will fill the surface preferentially and then diffuse inward. The doping of Hf has an insignificant impact on the adsorption or dissociation behavior of oxygen in comparison to the pure ZrCo surface. However, a notable observation is that the doping of Hf resulted in a reduction in the diffusion barrier for oxygen from the surface to the subsurface by 0.61 eV. Consequently, our study suggests that doping Hf is not an advisable strategy for improving the ZrCo(110) surface’s resistance to O2 poisoning because of improved oxygen permeability.

Isotope engineering achieved by local coordination design in Ti-Pd co-doped ZrCo-based alloys

Deuterium/Tritium (D/T) handling in defined proportions are pivotal to maintain steady-state operation for fusion reactors. However, the hydrogen isotope effect in metal-hydrogen systems always disturbs precise D/T ratio control. Here, we reveal the dominance of kinetic isotope effect during desorption. To reconcile the thermodynamic stability and isotope effect, we demonstrate a quantitative indicator of Tgap and further a local coordination design strategy that comprises thermodynamic destabilization with vibration enhancement of interstitial isotopes for isotope engineering. Based on theoretical screening analysis, an optimized Ti-Pd co-doped Zr0.8Ti0.2Co0.8Pd0.2 alloy is designed and prepared. Compared to ZrCo alloy, the optimal alloy enables consistent isotope delivery together with a three-fold lower Tgap, a five-fold lower energy barrier difference, a one-third lower isotopic composition deviation during desorption and an over two-fold higher cycling capacity. This work provides insights into the interaction between alloy and hydrogen isotopes, thus opening up feasible approaches to support high-performance fusion reactors.

Effects and mechanism of Ti, Cu, Y, La, Ce, Pr, Nd and Sm substitutions on the anti-disproportionation performance of ZrCo alloy

The intermetallic compound ZrCo is widely considered a good choice to substitute uranium in storing gaseous tritium. Whereas the storage capacity fading induced by the disproportionation reaction which happens during the hydriding and dehydriding processes becomes the main obstacle to overcome at the present stage. In this work, the effects and mechanism of Ti, Cu, Y, La, Ce, Pr, Nd and Sm substitutions on the anti-disproportionation performance of ZrCo alloy were carefully investigated by combining experiments and first-principles calculations. By the investigation of Zr1-xTixCo (x = 0, 0.05, 0.10, 0.15 and 0.20), it is confirmed that the increase of Zr–H (8e) bond length and decrease of 8e site size are beneficial to prevent the access of H into the 8e site of ZrCoH3, which helps the improvement of anti-disproportionation performance. It has shown that rare-earth elements are preferred to substitute Zr than Co atom in ZrCo and ZrCoH3 compounds. While alloying rare-earth elements may not contribute significantly to the enhancement of the anti-disproportionation property of ZrCo alloy. Additionally, the charge density distribution and polarized density of states of undoped and doped ZrCoH3 crystals were clarified.

Superior oxygen-resistance and intrinsic mechanisms of coherent Pd/Pd3Zr@ZrCo structure with excellent cycling durability

As a promising candidate for hydrogen isotopes storage, ZrCo alloy suffers tremendously from the poisoning of impurity gases, especially in oxygen-containing atmospheres, but related effective modification method for long cycling durability is still lacking. In this work, the anti-oxygen-poisoning behaviors and mechanisms of virginal ZrCo and palladium-coated ZrCo with different heating evacuation methods were detailly investigated. Notably, the phase transition occurs during traditional heating evacuation (550 °C for 60 min) with the gradual generation of Pd3Zr from original Pd coating and ZrCo substrate. According to absorption behaviors and degeneration state of O πp-orbital peak from theoretical calculations, O2 undergoes spontaneous dissociation and strong hybridization at the surface of ZrCo and Pd3Zr, especially for ZrCo, while much weak surface absorption is recognized on Pd. Considering the superior anti-poisoning properties but weak substrate anchoring strength of Pd, it’s valuable to reconstruct the Pd/ZrCo interface to generate transition Pd3Zr layer that is less susceptible to hydrogen embrittlement. Accordingly, a coherent structure of Pd/Pd3Zr@ZrCo was successfully obtained by high temperature short time pretreatment (550 °C for 10 min), and its cycling capacity retention in O2-containg hydrogen atmosphere is significantly enhanced from initial 74.87 % after 5 cycles to 90.83 % after 10 cycles, which is superior to Pd-plating hydrogen storage alloys ever reported. The interface reconstruction of coherent structure proposed here can function as a promising strategy for construction of protective layer for all related surface engineering.

The thermal conductivity of ZrCo alloy under doping effect: First principles study

ZrCo alloy is considered to be one of the most promising materials for hydrogen isotope treatment in the International Thermonuclear Experimental Reactor (ITER) due to its significant advantages in dehydrogenation kinetics, thermodynamics, and safety. The heating during the dehydrogenation process, on the other hand, can easily induce H2 to penetrate the surrounding environment, resulting in hydrogen embrittlement and threatening structural safety. The system's temperature regulation is very critical. The electronic thermal conductivity of ZrCo was computed using the BoltzTraP2 program and the constant relaxation time approximation based on density functional theory (DFT). The phonon thermal conductivity is calculated by lattice dynamics using the finite displacement supercell method. Between 300 K and 800 K, the thermal conductivity and electrical conductivity of ZrCo alloy were effectively predicted for the first time. The effects of Ti and V doping on ZrCo alloy thermal conductivity were investigated. The results show that when temperature rises, phonon-electron and phonon-phonon scattering will be enhanced. Resistance and thermal resistance will also rise, while conductivity and thermal conductivity would decrease. The doping of Ti and V elements will reduce the electronic thermal conductivity of the system. Different concentrations of doping bring different degrees of defects, affecting the average electron-phonon free path, and thereby reducing thermal conductivity.

Spatial-confinement synthesis of single-crystal ZrCo nanoparticles for ultrafast and long-life hydrogen/hydrogen isotope storage

ZrCo alloy is a safe and low-cost H-isotope storage material for controlled nuclear fusion, but traditional ZrCo prepared by smelting method suffer from slow gas uptake/release kinetics and serious degradation of cycle performance. Here, a “bottom-up” synthesis method is developed to prepare highly crystalline and high-purity ZrCo micron-/nanoparticles via a spatial-confinement strategy. The size-dependent hydrogen storage performances are systematically investigated from the perspectives of lattice constant, crystallinity, grain boundary, stress, and disproportionation phase transition. Compared with micron-scale polycrystalline smelted-ZrCo, the comprehensive performances of nanoscale ZrCo single crystals are significantly improved, including a 19-fold increase in kinetic rate, a ∼ 50% reduction of disproportionation ratio, and a two-fold improvement in cycle stability. This study provides a promising direction and an efficient synthetic method for the preparation of high-performance ZrCo alloys, which will facilitate their application in controlled nuclear fusion.

Effects of thickness and Ti substitutions on the anti-disproportionation behavior of ZrCo alloy films

ZrCo alloy has been considered as a tritium storage material to replace uranium for large-scale hydrogen isotope storage and delivery in tritium plant of the magnetic confinement nuclear fusion reactor. However, the disproportionation of ZrCo greatly obstructed its aspects to engineering application. A multifaceted understanding about the intrinsic nature of disproportionation reaction, and proposing anti-disproportionation strategies from material design have always been the bottleneck and hotspot in the tritium science and technology field. Herein, we studied the anti-disproportionation properties of Zr(Ti)Co alloy with thin film structure, and the effects of film thickness and Ti substitutions on the anti-disproportionation properties of the films were obtained. Firstly, a series of ZrCo films with different deposited time were prepared by magnetron sputtering instrument. The disproportionation ratio of the 2 h deposited ZrCo film (1.641μm) is 23.9%, and attenuated with the increase of film thickness. It indicates that the anti-disproportionation properties of the film structure is significantly better than that of ZrCo particle (68%). The microtopography analysis shows that the micro stress in the film structure is beneficial to hinder the disproportionation process. However, the hydrogenation reaction is also obviously inhibited in the ZrCo film. In addition, Ti doping can further improve its anti-disproportionation performance (10.3–7.3% for the 2 h deposited Zr1-xTixCo film) without significantly reducing the hydrogen absorption capacities of the ZrCo flims. The anti-disproportionation performance is closely related to the weakened interaction between Zr and H atoms, after Ti doping into the ZrCo flim, leading to the impaired driving force for disproportionation reaction. The study in this work can provide an important reference for the anti-disproportionation modification of ZrCo alloys.

Achieving excellent CO2 poisoning resistance of ZrCo hydrogen isotope storage material by surface reconstruction strategy

ZrCo alloy has been treated as the most promising candidate for hydrogen isotope storage in the International Thermonuclear Experimental Reactor (ITER). However, its poisoning resistance properties still remain challenging since the presence of impurity gas of CO2. Herein, the poisoning resistance behaviors and mechanism of ZrCo in H2+CO2 mixed gas were systematically investigated. Surprisingly, even trace amounts of CO2 can strongly deteriorate hydrogenation kinetics of ZrCo, which can be mitigated by further increasing the inputting pressure of the mixed gas. Such poisoning phenomenon can be attributed to the selective preferential absorption of CO2 on the ZrCo surface. Namely, the absorbed CO2 occupies the active sites on the surface and thus significantly blocks the absorption or dissociation of H2. Therefore, we proposed an in-situ surface reconstruction strategy by high-temperature treatment at 550 °C in H2+CO2 mixed gas. Specifically, in-situ formed metallic Co nanoclusters were generated on ZrCo surface, which are not only tough to be poisoned by CO2 contamination, but also can function as the catalytic active sites for H2 dissociation. Thus, an enhanced CO2 poisoning tolerance of ZrCo was achieved through the novel in-situ surface reconstruction strategy.

Positive correlation of Nb/Cr doping with dehydrogenation performance of ZrCo-based hydrides

It is well known that element substitution is vital to an improvement of hydrogen storage capacity degraded by hydrogen-induced disproportionation of zirconium-cobalt (ZrCo) alloy. Contrary to other studies, this work is devoted to investigating the hydrogen desorption behavior of Zr1-xNbxCo1-yCryH3 (x = 0–0.25 and y = 0–0.125) systems formed by Nb substitution and Nb/Cr co-substitution in the ZrCoH3 crystal using the first-principles calculations based on the density functional theory. Firstly, the preferred positions of Nb and Nb/Cr substitutions are determined through the minimum total energy. Lattice constants and the density of states are employed to characterize the bonding behavior between atoms. The thermodynamic properties of Zr1-xNbxCo1-yCryH3 are also assessed by the enthalpy of formation and equilibrium hydrogen pressure. It is shown that both the thermodynamic stability and dehydrogenation temperature of ZrCoH3 decrease by increasing the Nb content, which is attributed to the fact that the Zr–H and Co–H binding capabilities are weakened by the presence of Nb. In addition, there are weaker thermal stability, lower dehydrogenation temperature, smaller volume of 8e site, and comparable volume of the hydride after ZrCoH3 is co-substituted by Nb and Cr, thereby promoting the hydrogen release and enhancing the anti-disproportionation performance. Clearly, both Nb doping and Nb/Cr co-doping possess a positive effect on the hydrogen desorption ability of ZrCoH3. More importantly, it is discoverable that compared to other substitution systems, the dehydrogenation temperature is the least for the Zr0.75Nb0.25Co0.875Cr0.125 hydride, highlighting that Nb and Cr co-substitution is more beneficial to improving the dehydrogenation performance of ZrCo-based alloy.

Isotope effect on hydrogen storage properties of Ti and Nb co-substituted ZrCo alloy

In our previous study, we showed that the anti-disproportionation properties of Zr0.8Ti0.2-xNbxCo alloys were remarkably improved by the co-substitution of Zr with Ti and Nb. However, the practical application of these alloys in handling of hydrogen isotopes necessitates the first hand knowledge of hydrogen isotope effect. Herein, we discuss the hydrogen isotope effect on storage properties of Zr0.8Ti0.2-xNbxCo alloys. According to PCT measurements on desorption of deuterium from the Zr0.8Ti0.2-xNbxCo deuterides and comparison with corresponding hydrides, the deuterides require relatively lower temperature to achieve the desired equilibrium pressure. DSC measurements reveal a significant decrease in the activation energy for hydrogen/deuterium desorption reactions when Zr is substituted with Ti and Nb. Furthermore, it is observed that the activation energy of deuterium desorption is lower than the desorption of hydrogen from analogous hydride. Isotope effect on isothermal disproportion studies on Zr0.8Ti0.2-xNbxCo-deuterides divulge that Zr0.8Ti0.2-xNbxCo-deuterides have superior anti-disproportionation properties over corresponding hydrides, and further improvement is anticipated for the Zr0.8Ti0.2-xNbxCo-tritides. This study revealed the significant impact of Ti and Nb co-substitution on hydrogen isotope storage properties of Zr0.8Ti0.2-xNbxCo alloys, making them potential candidates for handling hydrogen isotopes.

Honeycomb ZrCo Intermetallic for High Performance Hydrogen and Hydrogen Isotope Storage

Hydrogen isotope storage materials are of great significance for controlled nuclear fusion, which is promising to provide unlimited clean and dense energy. Conventional storage materials of micrometer-sized polycrystalline ZrCo alloys prepared by the smelting method suffer from slow kinetics, pulverization, disproportionation, and poor cycling stability. Here, we synthesize a honeycomb-structured ZrCo composed of highly crystalline submicrometer ZrCo units using electrospray deposition and magnesiothermic reduction. Compared with conventional ones, honeycomb ZrCo does not require activation and exhibits more than 1 order of magnitude increase in kinetic property. Owing to low defects and low stress, the anti-disproportionation ability and cycling stability of honeycomb ZrCo are also obviously higher than those of conventional ZrCo. Moreover, the interfacial stress (due to hydrogenation/dehydrogenation) as a function of particle radius is established, quantitatively elucidating that small-sized ZrCo reduces stress and pulverization. This study points out a direction for the structural design of ZrCo alloy with high-performance hydrogen isotope storage.

First Principle Study on the Influence Mechanism of Impurity Gas O<sub>2</sub> on the Adsorption Properties of Alloy ZrCo

The adsorption behavior of gases on the surface of ZrCo alloy has an important influence on its hydrogen storage performance. The adsorption behavior of O₂ on ZrCo(110) surface was investigated using the first principles based on the pseudopotential plane wave method. The results of adsorption energy and charge analysis showed that the most stable geometry configuration was B3(Zr-Co Bridge site) and the adsorption energy was −8.124 eV. The density of states and differential charge density analysis showed that the adsorption behavior of O₂ on ZrCo (110) surface was strong chemical adsorption, and the oxygen-oxygen bond broke. The essence of bonding between O atom and ZrCo (110) surface atom was that the electron orbit of O atom overlapped with the electron orbit of the surface atom. It was that the 2s and 2p orbital electrons of O atom overlapped with the 4p and 4d orbital electrons of Zr atom and the 3d orbital electrons of Co atom on the surface. The research results have a positive role in revealing the poisoning mechanism of ZrCo alloy in impurity gases.

Remarkable enhancement in durability of ZrCo alloy against hydrogen induced disproportionation by Ti and Nb co-substitution

Considering the thermodynamic stability of various hydrides, a strategy has been employed to improve the hydrogen isotope storage properties of ZrCo alloy which involves partial co-substitution of Zr with Ti and Nb. Herein, alloys of composition Zr0.8Ti0.2-xNbxCo (x = 0.05, 0.1, 0.15) is prepared, characterized and the effect of Ti and Nb doping on hydrogen storage properties of parent ZrCo alloy is investigated. XRD analysis confirmed the formation of desired pure cubic phase of all the synthesized alloys similar to ZrCo phase. The presence of a single plateau in hydrogen desorption pressure-composition isotherms confirms single step hydrogen absorption-desorption behavior in Zr0.8Ti0.2-xNbxCo alloys. The equilibrium pressure of hydrogen desorption decreases marginally with increasing Nb content in Zr0.8Ti0.2-xNbxCo alloys which is further corroborated by differential scanning calorimetry measurements. Investigation of hydrogen induced disproportionation behavior in ITER-simulating condition revealed substantial impact of co-substitution of Ti and Nb on anti-disproportionation properties of ZrCo alloy. These remarkable properties make the Ti and Nb co-substituted quaternary alloys a desirable material for hydrogen isotope storage and delivery application.

First-principles study on the crystal structure stability and hydrogen storage mechanism of hydrogen occupancy in interstitial sites in ZrCo compounds

To study the properties of Zr 8 Co 8 H in the α-phase process of hydrogen storage, the effects of three types of H occupy sites in the ZrCo alloy on the crystal structure characteristics and their stability were investigated under the framework of a first-principles study. Two types of octahedral gaps were determined after crystal structure optimization, where the O1 octahedron was composed of two Co atoms and four Zr atoms, while O2 had two Zr atoms at its symmetry axis and four Co atoms in the middle vertical plane. The lattice constant, gap volume, and formation enthalpy results showed that Zr 8 Co 8 H O1 hydrides easily formed preferentially compared with Zr 8 Co 8 H O2 . By substituting the enthalpy changes into the pressure-composition isotherm (PCT) curve during the hydrogen absorption process, Zr 8 Co 8 H O2 facilitated the following hydrogen absorption process. In addition, the partial density of states (PDOS), charge difference density, the Mulliken population, the magnetic moment, and mechanical constants of three compounds were investigated to further verify that the O1 octahedral hydrogen placeholder had priority with superior lattice stability of the Zr 8 Co 8 H O1 structure.

Effect of isostructural phase transition on cycling stability of ZrCo-based alloys for hydrogen isotopes storage

ZrCo alloy as a promising candidate for hydrogen isotopes storage and delivery in the international thermonuclear experimental reactor (ITER) has attracted considerable attention. However, its capacity retention after 50 cycles is 22.4%, resulting from the disproportionation reaction during repeated phase transitions between cubic ZrCo phase and orthorhombic ZrCoH3 phase. Herein, a single isostructural phase transition with high thermal stability and structural stability in ZrCo-H system is achieved by multicomponent substitution for the first time. Considering the computational screening results, cost and gravimetric hydrogen capacity, a series of Zr0.8Nb0.2Co0.6Cu0.4−xNix (x = 0.2–0.3) alloys are designed and synthesized. The compositional dependence of phase component is further discussed in detail. Specifically, Zr0.8Nb0.2Co0.6Cu0.15Ni0.25 alloy with single orthorhombic phase exhibits high thermal stability (up to 550 °C) and maintains the orthorhombic structure during the de-/hydrogenation process at 380 °C. Thermodynamic destabilization of hydride (ΔH = 71.95 kJ·mol−1 H2) and nearly no de-/hydrogenation hysteresis contribute to a significantly low desorption temperature of 283 °C at 100 kPa. Thanks to superior thermal stability and structural stability, no attenuation of hydrogen storage performances including thermodynamics and kinetics can be observed during 200 de-/hydrogenation cycles, and the supereminent cycling stability of 100% and cyclic hydrogen capacity of 1.65 wt% are achieved. Combined with first-principles calculations, the improved cycling stability of Zr0.8Nb0.2Co0.6Cu0.15Ni0.25 alloy can be ascribed to the reduced lattice expansion and atomic motion during the orthorhombic isostructural phase transition.

The mechanism of anti-disproportionation for Ti-doped ZrCo alloys

For the disproportionation mechanism of ZrCo alloy, the unstable occupation of H atoms to 8e sites was considered to be the driving force of hydrogen-induced disproportionation reaction in ZrCo alloys. Titanium metal (Ti) is employed as one of the candidates for improving ZrCo alloys by element substitution. In this paper, the anti-disproportionation mechanism of Ti-doped ZrCo alloys with a large-scale proportional element doping, has been studied in detail by combining experimental results and calculations. The thermodynamic properties and anti-disproportionation properties of Zr1-xTixCo (X = 0–0.5) alloys were investigated by sievert methods. Taking in view the known Case 1 which states that H(4c2) atoms diffuse into the 8e sites and Case 2 based on a new assumption involving the extra occupation of H(8e) atoms, the occupying effect of H(8e) atoms of different Zr1-xTixCoH3 (X = 0–0.5) and the property of 4c2 sites as the source of H(8e) atoms were analyzed by Density functional theory. The results indicated that the occupancy of H(8e) atoms and the bond length of Zr-H(8e) are decisive factors affecting the anti-disproportionation performance of ZrCo alloys, and the influence of Ti substitution on the H(8e) occupancy mainly originates from the (8e-4c2) barrier.

First-Principles Study of the Effect of Titanium Doping on Carbon Monoxide Poisoning Properties of Zirconium-Cobalt Alloys

It is very important to study impurity gas poisoning in ZrCo alloy because it is associated directly with the performance of ZrCo alloy as a hydrogen storage material. In this work, the effects of atomic replacement on the mechanism and properties of CO impurity gas poisoning in doped (Ti) ZrCo hydrogen storage alloys were investigated using the first principles method, based on the pseudopotential plane wave method. The adsorption energy, lattice constant, density of states, and charge density difference of the compounds before and after doping were calculated. Then, surface adsorption models of the ZrCo and Zr0.8Ti0.2Co alloys were established with the assistance of a conventional model. The resulting adsorption energy values of the clean surface and the surface adsorption energy values in the presence of CO impurity gases manifested that the Ti element-doped Zr0.8Ti0.2Co alloy was more susceptible to CO gas poisoning compared to ZrCo, which was consistent with the existing experimental results. In addition, by analyzing the conventional model, the electrons from the doped atoms overlapped with the surrounding electrons of C atoms, the phenomenon of orbital hybridization occurred, and the interactions increased. Consequently, Ti doping was not conducive to ZrCo to improve the ability to resist CO poisoning. The research results of this paper have laid a good foundation for the study of the effect of Ti doping on the antitoxicity performance.