Mg-based amorphous alloys exhibit efficient catalytic performance and excellent biocompatibility with a promising application probability,specifically in the field of azo dye wastewater degradation.However,the problem...Mg-based amorphous alloys exhibit efficient catalytic performance and excellent biocompatibility with a promising application probability,specifically in the field of azo dye wastewater degradation.However,the problems like difficulty in preparation and poor cycling stability need to be solved.At present,Mg-based amorphous alloys applied in wastewater degradation are available in powder and ribbon.The amorphous alloy powder fabricated by ball milling has a high specific surface area,and its reactivity is thousands of times better than that of gas atomized alloy powder.But the development is limited due to the high energy consumption,difficult and costly process of powder recycling.The single roller melt-spinning method is a new manufacturing process of amorphous alloy ribbon.Compared to amorphous powder,the specific surface area of amorphous ribbon is relatively lower,therefore,it is necessary to carry out surface modification to enhance it.Dealloying is a way that can form a pore structure on the surface of the amorphous alloys,increasing the specific surface area and providing more reactive sites,which all contribute to the catalytic performance.Exploring the optimal conditions for Mg-based amorphous alloys in wastewater degradation by adjusting amorphous alloy composition,choosing suitable method to preparation and surface modification,reducing cost,expanding the pH range will advance the steps to put Mg-based amorphous alloys in industrial environments into practice.展开更多
Aiming to elucidate the hydrogen absorption/desorption cycling properties of Mg-based alloys with in-situ formed Mg_(2)Ni and LaH_(x)(x=2,3)nanocrystallines,the hydrogen storage cycle stability,hydriding/dehydriding c...Aiming to elucidate the hydrogen absorption/desorption cycling properties of Mg-based alloys with in-situ formed Mg_(2)Ni and LaH_(x)(x=2,3)nanocrystallines,the hydrogen storage cycle stability,hydriding/dehydriding cycling kinetics and thermodynamic stability of the experimental alloys have been investigated in detail.The results show that the Mg-Ni-La alloys exhibit improved hydrogen storage cycling properties and can remain storage hydrogen above 5.5 wt%after 200 cycles.With the increase of cycling numbers,the dehydrogenation rates of the experimental samples increase firstly and then gradually decrease,and eventually maintain relative stable state.Microstructure observation reveals that powders sintering and hydrogen decrepitation both exist during hydrogen absorption/desorption cycles due to repeated volume expansion and contraction.Meanwhile,the in-situ formed LaH_(x)(x=2,3)and Mg_(2)Ni nanocrystallines stabilize the microstructures of the particles and hinder the powders sintering.After 200 cycles,the average particle size of the experimental samples decreases and the specific surface area apparently increases,which leads to the decomposition temperatures of MgH_(2)and Mg_(2)NiH_(4)slightly shift to lower temperatures.Moreover,Mg_(2)Ni and LaH_(x)(x=2,3)have been proven to be stable catalysts during long-term cycling,which can still uniformly distribute within the powders after 200 cycles.展开更多
With the depletion of fossil fuels and global warming,there is an urgent demand to seek green,low-cost,and high-efficiency energy resources.Hydrogen has been considered as a potential candidate to replace fossil fuels...With the depletion of fossil fuels and global warming,there is an urgent demand to seek green,low-cost,and high-efficiency energy resources.Hydrogen has been considered as a potential candidate to replace fossil fuels,due to its high gravimetric energy density(142 MJ kg^(-1)),high abundance(H_(2)O),and environmentalfriendliness.However,due to its low volume density,effective and safe hydrogen storage techniques are now becoming the bottleneck for the"hydrogen economy".Under such a circumstance,Mg-based hydrogen storage materials garnered tremendous interests due to their high hydrogen storage capacity(~7.6 wt%for MgH_(2)),low cost,and excellent reversibility.However,the high thermodynamic stability(ΔH=-74.7 kJ mol^(-1)H_(2))and sluggish kinetics result in a relatively high desorption temperature(>300℃),which severely restricts widespread applications of MgH_(2).Nano-structuring has been proven to be an effective strategy that can simultaneously enhance the ab/de-sorption thermodynamic and kinetic properties of MgH_(2),possibly meeting the demand for rapid hydrogen desorption,economic viability,and effective thermal management in practical applications.Herein,the fundamental theories,recent advances,and practical applications of the nanostructured Mg-based hydrogen storage materials are discussed.The synthetic strategies are classified into four categories:free-standing nano-sized Mg/MgH_(2)through electrochemical/vapor-transport/ultrasonic methods,nanostructured Mg-based composites via mechanical milling methods,construction of core-shell nano-structured Mg-based composites by chemical reduction approaches,and multi-dimensional nano-sized Mg-based heterostructure by nanoconfinement strategy.Through applying these strategies,near room temperature ab/de-sorption(<100℃)with considerable high capacity(>6 wt%)has been achieved in nano Mg/MgH_(2)systems.Some perspectives on the future research and development of nanostructured hydrogen storage materials are also provided.展开更多
Grain growth of magnesium(Mg)and its hydride is one of the main reasons for kinetic and capacity degradation during the hydrogen absorption and desorption cycles.To solve this problem,herein we propose a novel method ...Grain growth of magnesium(Mg)and its hydride is one of the main reasons for kinetic and capacity degradation during the hydrogen absorption and desorption cycles.To solve this problem,herein we propose a novel method involving synergistic effect of inside embedded metals and outside coated graphene to limit the growth of Mg and its hydride grains.The graphene coated Mg-Y-Al alloys were selected as a model system for demonstrating this positive effect where the Mg_(91)Y_(3)Al_(6)alloy was first prepared by rapidly solidified method and then high-pressure milled with 5 wt%graphene upon 5 MPa hydrogen gas for obtaining in-situ formed YAl_(2)and YH_(3)embedded in the MgH_(2)matrix with graphene shell(denoted as MgH_(2)-Y-Al@GR).In comparison to pure MgH_(2),the obtained MgH_(2)-Y-Al@GR composites deliver much better kinetics and more stable cyclic performance.For instance,the MgH_(2)-Y-Al@GR can release about 6.1 wt%H_(2)within 30 min at 300℃ but pure MgH_(2)only desorbs∼1.5 wt%H_(2).The activation energy for desorption of MgH_(2)-Y-Al@GR samples is calculated to be 75.3±9.1 kJ/mol that is much lower than approximately 160 kJ/mol for pure MgH_(2).Moreover,its capacity retention is promoted from∼57%of pure MgH_(2)to∼84%after 50th cycles without obvious particle agglomeration and grain growth.The synergistic effect of outside graphene coating with inside embedded metals which could provide a huge number of active sites for catalysis as well as inhibit the grain growth of Mg and its hydride is believed to be responsible for these.展开更多
A sort of rare earth Mg-based system hydrogen storage alloys with AB3-type was prepared by double-roller rapid quenching method. The alloys were nanocrystalline multi-phase structures composed of LaNi3 phase and LaNi5...A sort of rare earth Mg-based system hydrogen storage alloys with AB3-type was prepared by double-roller rapid quenching method. The alloys were nanocrystalline multi-phase structures composed of LaNi3 phase and LaNi5 phase by X-ray diffraction and scanning electron microscopy analyses, and the suitable absorption/desorption plateau was revealed by the measurement of P-C-I curve. Electrochemical studies indicate that the alloys exhibit good electrochemical properties such as high capacity and stable cycle life, and the discharge capacity is 369 mAh·g-1 at 0.2 C (72 mA·g-1). after 460 cycles, the capacity decay was only 19.4% at 2 C (720 mA·g-1).展开更多
The effect of heat-treatment process on the properties of Mm0.8Mg0.2(NiCoAlMn)3.5 hydrogen storage alloy was discussed . The electrochemical properties such as cycling stability, activation property, and the plateau v...The effect of heat-treatment process on the properties of Mm0.8Mg0.2(NiCoAlMn)3.5 hydrogen storage alloy was discussed . The electrochemical properties such as cycling stability, activation property, and the plateau voltage of the alloy which was heat-treated in various temperatures and times had different changes during the cycle process, the optimum heat-treatment conditions of this alloy were determined by this work.展开更多
The kinetics equation of the Mg-based hydrogen storage alloys (Mg-Ni-MO) was established by the shell and shrinking core model. The total coefficients of the kinetics equation of the hydrogen absorption and desorption...The kinetics equation of the Mg-based hydrogen storage alloys (Mg-Ni-MO) was established by the shell and shrinking core model. The total coefficients of the kinetics equation of the hydrogen absorption and desorption process with shell diffusion as the controlling step were determined by semi-empirical and semi-theoretical methods, and the apparent activation energy of the hydrogen absorption process was obtained. The calculation results can well accord with the experimental data, and can well forecast the hydrogen storage capacity and absorption rate at different times. By using the kinetics equation, the effects of temperature and pressure on the hydrogen storage process can also be well understood. The kinetics equation is helpful for the design of the hydrogen storage container.展开更多
The Mg-based hydrogen storage alloys Mg2Ni, Mg2Ni0.7Fe0.3 and Mgl.7Alo.3Ni were successfully synthesized by a two-step process (sintering and ball milling). The crystal structure and microstructure were examined by ...The Mg-based hydrogen storage alloys Mg2Ni, Mg2Ni0.7Fe0.3 and Mgl.7Alo.3Ni were successfully synthesized by a two-step process (sintering and ball milling). The crystal structure and microstructure were examined by X-ray diffraction, Scanning Electron Microscope and Malvern particle size analyzer. New phase appears in the tripe alloys doped with A1 and Fe, and the particle size ranges from 3μm to 5 μm. The electrochemical performance studies indicate that the partial substitution of AI for Mg, and Fe for Ni significantly improve the cycle life, reversibility of hydrogen absorption and desorption. The diffusion process is the control step in the electrode reaction of hydrogen storage alloys.展开更多
Recent development of Mg and Mg-based hydrogen storage alloys used in Ni-MH battery was discussed extensively. The results obtained from recent studies prove that these alloys with nanocrystalline/amorphous structure ...Recent development of Mg and Mg-based hydrogen storage alloys used in Ni-MH battery was discussed extensively. The results obtained from recent studies prove that these alloys with nanocrystalline/amorphous structure formed by mechanical alloying (MA) or mechanical grinding (MG) have good electrode characteristics. In general, MA or MG, and elemental substitution alloying are regarded as the effective means to seek new system of Mg-based alloys and nano-composite with improved electrode characteristics. However, until now, the currently known improvement in these electrode characteristics is still far from reach to that required for commercial application.展开更多
Mg and its alloys are drawing huge attention since the last two decades as a viable option for temporary implants applications.A commendable progress has already been made in the development of these alloys.The biodeg...Mg and its alloys are drawing huge attention since the last two decades as a viable option for temporary implants applications.A commendable progress has already been made in the development of these alloys.The biodegradable nature of Mg,appreciable biocompatibility of elemental Mg,and its close resemblance to natural bone in terms of density and elastic modulus make them highly preferable option amongst other available alternatives in this field.This review article presents an overview covering the recent advancements made in the field of Mg-based biodegradable implants for orthopaedic implant applications.The paper focuses on alloy development and fabrication techniques,the state of the art of important Mg-based alloy systems in terms of their mechanical properties,in-vitro and in-vivo degradation behaviour and cytotoxicity.Further,the paper reviews the current progress achieved in the clinical transition of Mg-based alloys for orthopaedic fixtures.The review also includes the degradation mechanisms of the alloys in physiological environment and highlights the mismatch existing between the rate of bone healing and alloy degradation due to rapid corrosion of the alloys in such environment,which has still restricted their widespread application.Finally,the surface coating techniques available for the alloys as an effective way to reduce the degradation rate are reviewed,followed by a discussion on the future research prospects.展开更多
The composites comprised of Co nanoparticle and C nanosheet were prepared though a high-temperature carbonization reaction.The catalysis of Co@C composites on the hydrogen storage behavior of Mg_(90)Ce_(5)Y_(5)alloy w...The composites comprised of Co nanoparticle and C nanosheet were prepared though a high-temperature carbonization reaction.The catalysis of Co@C composites on the hydrogen storage behavior of Mg_(90)Ce_(5)Y_(5)alloy was investigated in detail by XRD,SEM,TEM,PCI,and DSC method.Because of the synergistic catalytic function of C and Co in C@Co nanocomposites,the Mg_(90)Ce_(5)Y_(5)alloy with 10 wt.%C@Co shows the excellent hydrogen absorption and desorption performances.Time for releasing hydrogen reduces from 150 min to 11 min with the addition of the C@Co composites at the temperature of 300℃.Meanwhile,the dehydrogenation activation energy also declines from 130.3 to 81.9 kJ mol^(-1)H_(2)after the addition of the C@Co composites.This positive effect attributes to the C layer with the high defect density and the Co nanoparticles,which reduces the energy barriers for the nucleation of Mg/MgH_(2)phase and the recombination of hydrogen molecule.Besides,the C@Co composites also improve the activation property of the Mg_(90)Ce_(5)Y_(5)alloy which was folly activated in the first cycle.Moreover,the temperature for initial dehydrogenation and the endothermic peak of the alloy hydride were also decreased.Although the addition of the C@Co composites increases the plateau pressures and decreases the value of the decomposition enthalpy,these differences are so small that the improvement on thermodynamics can hardly be seen.展开更多
Mg-based materials have been intensively studied for hydrogen storage applications due to their high energy density up to 2600 Wh/kg or 3700 Wh/L.However,the Mg-based materials with poor kinetics and the necessity for...Mg-based materials have been intensively studied for hydrogen storage applications due to their high energy density up to 2600 Wh/kg or 3700 Wh/L.However,the Mg-based materials with poor kinetics and the necessity for a high temperature to achieve 0.1 MPa hydrogen equilibrium pressure limit the applications in the onboard storage in Fuel cell vehicles(FCVs).Over the past decades,many methods have been applied to improve the hydriding/dehydriding(H/D)kinetics of Mg/MgH 2 by forming amorphous or nanosized particles,adding catalysts and employing external energy field,etc.However,which method is more effective and the intrinsic mechanism they work are widely differing versions.The hydrogenation and dehydrogenation behaviors of Mg-based alloys analyzing by kinetic models is an efficient way to reveal the H/D kinetic mechanism.However,some recently proposed models with physical meaning and simple analysis method are not known intimately by researchers.Therefore,this review focuses on the enhancement method of kinetics in Mg-based hydrogen storage materials and introduces the new kinetic models.展开更多
Mg-based hydrogen storage materials are considered to be one of the most promising solid-state hydrogen storage materials due to their large hydrogen storage capacity and low cost. However, slow hydrogen absorption/de...Mg-based hydrogen storage materials are considered to be one of the most promising solid-state hydrogen storage materials due to their large hydrogen storage capacity and low cost. However, slow hydrogen absorption/desorption rate and excessive hydrogen absorption/desorption temperature limit the application of Mg-based hydrogen storage materials.The present paper reviews the advances in the research of Mg-based hydrogen storage film in recent years, including the advantage of the film, the function theory of fabricating method and its functional theory, and the influencing factors in the technological process. The research status worldwide is introduced in detail. By comparing pure Mg, Pd-caped Mg, nonpalladium capped Mg, and Mg alloy hydrogen storage films, an ideal tendency for producing Mg-based film is pointed out,for example, looking for a cheap metal element to replace the high-priced Pd, compositing Mg film with other hydrogen storage alloy of catalytic elements, and so on.展开更多
Mg-based hydrogen storage alloys are considered as a promising candidate for hydrogen system because of its lightweight, high storage capacity, low price and rich mineral resources. In detail, we reviewed the preparat...Mg-based hydrogen storage alloys are considered as a promising candidate for hydrogen system because of its lightweight, high storage capacity, low price and rich mineral resources. In detail, we reviewed the preparation and properties of Mg-Ni-based hydrogen storage alloys. All kinds of attempts have been done to improve the hydriding and dehydriding behaviors. It is found that the partial substitution of foreign elements can decrease the hydrogen absorption temperature, especially the substitution of a more electronegative element, such as AI and Mn. Mechanical alloying (MA) and mechanical grinding (MG) are the most effective methods to improve the hydriding/dehydriding kinetics and electrochemical capacity, and decrease the desorption temperature. but the corrosion resistance is so poor that the 80% of maximum capacity is lost within ten cycles. Microencapsulation is a useful measurement for improving the corrosion resistance and electrocatalytic activity. fn order to improve the properties of the alloys for practical application, the alloys should have a large number of defects, which give activated sites, subsequently, MA, MG and electroless plating should be used to improve the hydriding/dehydriding kinetics and protect the surface of alloys, respectively. The new composite Mg-based alloys give a new way for the hydrogen storage material to practical application. Furthermore we put forward several problems which will be discussed in future.展开更多
Thethermal stability and the kinetics of grain growth of nanocrystalline Mg-6Al-1Zn and Mg-6Al-1Zn-1Si alloys prepared via mechanical alloying were investigated. It started with elemental powders, using a variety of a...Thethermal stability and the kinetics of grain growth of nanocrystalline Mg-6Al-1Zn and Mg-6Al-1Zn-1Si alloys prepared via mechanical alloying were investigated. It started with elemental powders, using a variety of analytical techniques including differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive spectrometry. The kinetics of grain growth in isothermal annealing was investigated. The XRD results show that, although the grain sizes of both material systems increase as the annealing temperature rises, the Si-containing system displays a relatively smaller grain size, i.e., 60 nm compared with 72 nm in Mg-6Al-1Zn system, after being exposed to 350 ℃ for 1 h. The second-phase intermetallic particle Mg2Si formed during the isothermal annealing of Mg-6Al-1Zn-1Si system could influence not only the activation energy but also the exponent of kinetic equation. Higher hardness values obtained in the Si-containing system would be due to the formation of Mg2Si intermetallic phase.展开更多
As an example of the La-Mg-Y system, the method how to set up the themaodynamic model of individual phases was introduced in the process of thermodynamic optimization. The solution phases (liquid, body-centered cubic...As an example of the La-Mg-Y system, the method how to set up the themaodynamic model of individual phases was introduced in the process of thermodynamic optimization. The solution phases (liquid, body-centered cubic, face-centered cubic, hexagonal close-packed and double hexagonal close-packed) were modeled with the Redlich-Kister equation. The compound energy model has been used to describe the thermodynamic functions of the intermetallic compounds in the La-Mg-Y systems. The compounds Mg2Y, Mg24Y5, Mg12La, Mg17La2, Mg41Las, Mg3La and Mg2La in the La-Mg-Y system were treated as the formulae (Mg,Y)2(La,Mg,Y), Mg24(La,Mg,Y)4Y, Mg12(La, Y), Mg17(La,Y)2, Mg41(La,Y)5, Mg3(La,Mg,Y) and Mg2(La, Y), respectively. A model (La, Mg,Y)0.5(La,Mg,Y)0.5 was applied to describe the compound MgM formed by MgLa and MgY in order to cope with the order-disorder transition between body-centered cubic solution (A2) and MgM with CsCl-type structure (B2) in the La-Mg-Y system. The Gibbs energies of individual phases were optimized in the La-Mg, La-Y and La-Mg-Y systems by CALPHAD technique. The projection of the liquidus surfaces for the La-Mg-Y system was predicted. The Mg-based alloys database including 36 binary and 15 ternary systems formed by Mg, Al, Cu, Ni, Mn, Zn and rare earth elements was set up in SGTE standard.展开更多
Mg-25 wt% Mg2Ni composite was prepared by sintered method, hydrided at 613 K and then ball-milled with 1.5 wt% PdC12 additive for 51 h. The effects of PdCl2 on the hydriding and dehydriding behavior of Mg-25 wt% Mg2Ni...Mg-25 wt% Mg2Ni composite was prepared by sintered method, hydrided at 613 K and then ball-milled with 1.5 wt% PdC12 additive for 51 h. The effects of PdCl2 on the hydriding and dehydriding behavior of Mg-25 wt% Mg2Ni composite were investigated. The absorption and desorption rate of the composite with PdCl2 is fast and the hydrogen storage capacity is more than that of the composite without PdCl2. The maximum hydrogen storage capacity reached 3.48 wt% at 373 K, and 5.05 wt% H at 453 K, respectively. The improvement of sorption and desorption kinetics is attributed to the catalytic effect of PdCl2, and the grain refining and lattice strain introduced by ball milling.展开更多
The Ni-coated carbon nanotubes(Ni@CNT)composite was synthesized by the facile“filtration+calcination”of Ni-based metal−organic framework(MOF)precursor and the obtained composite was used as a catalyst for MgH_(2).Mg...The Ni-coated carbon nanotubes(Ni@CNT)composite was synthesized by the facile“filtration+calcination”of Ni-based metal−organic framework(MOF)precursor and the obtained composite was used as a catalyst for MgH_(2).MgH_(2)was mixed evenly with different amounts of Ni@CNT(2.5,5.0 and 7.5,wt.%)through ball milling.The MgH_(2)−5wt.%Ni@CNT can absorb 5.2 wt.%H_(2)at 423 K in 200 s and release about 3.75 wt.%H_(2)at 573 K in 1000 s.And its dehydrogenation and rehydrogenation activation energies are reduced to 87.63 and 45.28 kJ/mol(H_(2)).The in-situ generated Mg_(2)Ni/Mg_(2)NiH4 exhibits a good catalytic effect due to the provided more diffusion channels that can be used as“hydrogen pump”.And the presence of carbon nanotubes improves the properties of MgH_(2)to some extent.展开更多
This study employs advanced electrochemical and surface characterization techniques to investigate the impact of electrochemical hydrogen charging on the corrosion behavior and surface film of the Ti-6Al-4V alloy.The ...This study employs advanced electrochemical and surface characterization techniques to investigate the impact of electrochemical hydrogen charging on the corrosion behavior and surface film of the Ti-6Al-4V alloy.The findings revealed the formation ofγ-TiH andδ-TiH_(2) hydrides in the alloy after hydrogen charging.Prolonging hydrogen charging resulted in more significant degradation of the alloy microstructure,leading to deteriorated protectiveness of the surface film.This trend was further confirmed by the electrochemical measurements,which showed that the corrosion resistance of the alloy progressively worsened as the hydrogen charging time was increased.Consequently,this work provides valuable insights into the mechanisms underlying the corrosion of Ti-6Al-4V alloy under hydrogen charging conditions.展开更多
Hydrogen storage alloys(HSAs)are attracting widespread interest in the nuclear industry because of the generation of stable metal hydrides after tritium absorption,thus effectively preventing the leakage of radioactiv...Hydrogen storage alloys(HSAs)are attracting widespread interest in the nuclear industry because of the generation of stable metal hydrides after tritium absorption,thus effectively preventing the leakage of radioactive tritium.Commonly used HSAs in the hydrogen isotopes field are Zr2M(M=Co,Ni,Fe)alloys,metallic Pd,depleted U,and ZrCo alloy.Specifically,Zr2M(M=Co,Ni,Fe)alloys are considered promising tritium-getter materials,and metallic Pd is utilized to separate and purify hydrogen isotopes.Furthermore,depleted U and ZrCo alloy are well suited for storing and delivering hydrogen isotopes.Notably,all the aforementioned HSAs need to modulate their hydrogen storage properties for complex operating conditions.In this review,we present a comprehensive overview of the reported modification methods applied to the above alloys.Alloying is an effective amelioration method that mainly modulates the properties of HSAs by altering their local geometrical/electronic structures.Besides,microstructural modifications such as nano-sizing and nanopores have been used to increase the specific surface area and active sites of metallic Pd and ZrCo alloys for enhancing de-/hydrogenation kinetics.The combination of metallic Pd with support materials can significantly reduce the cost and enhance the pulverization resistance.Moreover,the poisoning resistance of ZrCo alloy is improved by constructing active surfaces with selective permeability.Overall,the review is constructive for better understanding the properties and mechanisms of hydrogen isotope storage alloys and provides effective guidance for future modification research.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.52071276)the Natural Science Foundation of Chongqing,China(Grant No.CSTB2022NSCQ-MSX0440)the Fundamental Research Funds for the Central Universities(Grant No.SWUXDJH202313,SWU-KQ22083).
文摘Mg-based amorphous alloys exhibit efficient catalytic performance and excellent biocompatibility with a promising application probability,specifically in the field of azo dye wastewater degradation.However,the problems like difficulty in preparation and poor cycling stability need to be solved.At present,Mg-based amorphous alloys applied in wastewater degradation are available in powder and ribbon.The amorphous alloy powder fabricated by ball milling has a high specific surface area,and its reactivity is thousands of times better than that of gas atomized alloy powder.But the development is limited due to the high energy consumption,difficult and costly process of powder recycling.The single roller melt-spinning method is a new manufacturing process of amorphous alloy ribbon.Compared to amorphous powder,the specific surface area of amorphous ribbon is relatively lower,therefore,it is necessary to carry out surface modification to enhance it.Dealloying is a way that can form a pore structure on the surface of the amorphous alloys,increasing the specific surface area and providing more reactive sites,which all contribute to the catalytic performance.Exploring the optimal conditions for Mg-based amorphous alloys in wastewater degradation by adjusting amorphous alloy composition,choosing suitable method to preparation and surface modification,reducing cost,expanding the pH range will advance the steps to put Mg-based amorphous alloys in industrial environments into practice.
基金supported by Natural Science Foundation of Shaanxi Province,China(2017JM5079)The 111 project(No.B08040)is also acknowledged.
文摘Aiming to elucidate the hydrogen absorption/desorption cycling properties of Mg-based alloys with in-situ formed Mg_(2)Ni and LaH_(x)(x=2,3)nanocrystallines,the hydrogen storage cycle stability,hydriding/dehydriding cycling kinetics and thermodynamic stability of the experimental alloys have been investigated in detail.The results show that the Mg-Ni-La alloys exhibit improved hydrogen storage cycling properties and can remain storage hydrogen above 5.5 wt%after 200 cycles.With the increase of cycling numbers,the dehydrogenation rates of the experimental samples increase firstly and then gradually decrease,and eventually maintain relative stable state.Microstructure observation reveals that powders sintering and hydrogen decrepitation both exist during hydrogen absorption/desorption cycles due to repeated volume expansion and contraction.Meanwhile,the in-situ formed LaH_(x)(x=2,3)and Mg_(2)Ni nanocrystallines stabilize the microstructures of the particles and hinder the powders sintering.After 200 cycles,the average particle size of the experimental samples decreases and the specific surface area apparently increases,which leads to the decomposition temperatures of MgH_(2)and Mg_(2)NiH_(4)slightly shift to lower temperatures.Moreover,Mg_(2)Ni and LaH_(x)(x=2,3)have been proven to be stable catalysts during long-term cycling,which can still uniformly distribute within the powders after 200 cycles.
基金support from the National Key Research&Development Program(2022YFB3803700)of ChinaNational Natural Science Foundation(No.52171186)financial support from the Center of Hydrogen Science,Shanghai Jiao Tong University。
文摘With the depletion of fossil fuels and global warming,there is an urgent demand to seek green,low-cost,and high-efficiency energy resources.Hydrogen has been considered as a potential candidate to replace fossil fuels,due to its high gravimetric energy density(142 MJ kg^(-1)),high abundance(H_(2)O),and environmentalfriendliness.However,due to its low volume density,effective and safe hydrogen storage techniques are now becoming the bottleneck for the"hydrogen economy".Under such a circumstance,Mg-based hydrogen storage materials garnered tremendous interests due to their high hydrogen storage capacity(~7.6 wt%for MgH_(2)),low cost,and excellent reversibility.However,the high thermodynamic stability(ΔH=-74.7 kJ mol^(-1)H_(2))and sluggish kinetics result in a relatively high desorption temperature(>300℃),which severely restricts widespread applications of MgH_(2).Nano-structuring has been proven to be an effective strategy that can simultaneously enhance the ab/de-sorption thermodynamic and kinetic properties of MgH_(2),possibly meeting the demand for rapid hydrogen desorption,economic viability,and effective thermal management in practical applications.Herein,the fundamental theories,recent advances,and practical applications of the nanostructured Mg-based hydrogen storage materials are discussed.The synthetic strategies are classified into four categories:free-standing nano-sized Mg/MgH_(2)through electrochemical/vapor-transport/ultrasonic methods,nanostructured Mg-based composites via mechanical milling methods,construction of core-shell nano-structured Mg-based composites by chemical reduction approaches,and multi-dimensional nano-sized Mg-based heterostructure by nanoconfinement strategy.Through applying these strategies,near room temperature ab/de-sorption(<100℃)with considerable high capacity(>6 wt%)has been achieved in nano Mg/MgH_(2)systems.Some perspectives on the future research and development of nanostructured hydrogen storage materials are also provided.
基金financially supported by the Key Program for International S&T Cooperation Projects of China(No.2017YFE0124300)National Natural Science Foundation of China(No.52171205,51971002 and 52171197)+1 种基金Scientific Research Foundation of Anhui Provincial Education Department(Nos.KJ2020ZD26,KJ2021A0360)Anhui Provincial Natural Science Foundation for Excellent Youth Scholars(No.2108085Y16).
文摘Grain growth of magnesium(Mg)and its hydride is one of the main reasons for kinetic and capacity degradation during the hydrogen absorption and desorption cycles.To solve this problem,herein we propose a novel method involving synergistic effect of inside embedded metals and outside coated graphene to limit the growth of Mg and its hydride grains.The graphene coated Mg-Y-Al alloys were selected as a model system for demonstrating this positive effect where the Mg_(91)Y_(3)Al_(6)alloy was first prepared by rapidly solidified method and then high-pressure milled with 5 wt%graphene upon 5 MPa hydrogen gas for obtaining in-situ formed YAl_(2)and YH_(3)embedded in the MgH_(2)matrix with graphene shell(denoted as MgH_(2)-Y-Al@GR).In comparison to pure MgH_(2),the obtained MgH_(2)-Y-Al@GR composites deliver much better kinetics and more stable cyclic performance.For instance,the MgH_(2)-Y-Al@GR can release about 6.1 wt%H_(2)within 30 min at 300℃ but pure MgH_(2)only desorbs∼1.5 wt%H_(2).The activation energy for desorption of MgH_(2)-Y-Al@GR samples is calculated to be 75.3±9.1 kJ/mol that is much lower than approximately 160 kJ/mol for pure MgH_(2).Moreover,its capacity retention is promoted from∼57%of pure MgH_(2)to∼84%after 50th cycles without obvious particle agglomeration and grain growth.The synergistic effect of outside graphene coating with inside embedded metals which could provide a huge number of active sites for catalysis as well as inhibit the grain growth of Mg and its hydride is believed to be responsible for these.
文摘A sort of rare earth Mg-based system hydrogen storage alloys with AB3-type was prepared by double-roller rapid quenching method. The alloys were nanocrystalline multi-phase structures composed of LaNi3 phase and LaNi5 phase by X-ray diffraction and scanning electron microscopy analyses, and the suitable absorption/desorption plateau was revealed by the measurement of P-C-I curve. Electrochemical studies indicate that the alloys exhibit good electrochemical properties such as high capacity and stable cycle life, and the discharge capacity is 369 mAh·g-1 at 0.2 C (72 mA·g-1). after 460 cycles, the capacity decay was only 19.4% at 2 C (720 mA·g-1).
文摘The effect of heat-treatment process on the properties of Mm0.8Mg0.2(NiCoAlMn)3.5 hydrogen storage alloy was discussed . The electrochemical properties such as cycling stability, activation property, and the plateau voltage of the alloy which was heat-treated in various temperatures and times had different changes during the cycle process, the optimum heat-treatment conditions of this alloy were determined by this work.
文摘The kinetics equation of the Mg-based hydrogen storage alloys (Mg-Ni-MO) was established by the shell and shrinking core model. The total coefficients of the kinetics equation of the hydrogen absorption and desorption process with shell diffusion as the controlling step were determined by semi-empirical and semi-theoretical methods, and the apparent activation energy of the hydrogen absorption process was obtained. The calculation results can well accord with the experimental data, and can well forecast the hydrogen storage capacity and absorption rate at different times. By using the kinetics equation, the effects of temperature and pressure on the hydrogen storage process can also be well understood. The kinetics equation is helpful for the design of the hydrogen storage container.
基金Funded by the National High Technology Research and Development Program of China (Key Project) (2001AA 331050) and the Chongqing Applied Fundamental Research (7941-2).
文摘The Mg-based hydrogen storage alloys Mg2Ni, Mg2Ni0.7Fe0.3 and Mgl.7Alo.3Ni were successfully synthesized by a two-step process (sintering and ball milling). The crystal structure and microstructure were examined by X-ray diffraction, Scanning Electron Microscope and Malvern particle size analyzer. New phase appears in the tripe alloys doped with A1 and Fe, and the particle size ranges from 3μm to 5 μm. The electrochemical performance studies indicate that the partial substitution of AI for Mg, and Fe for Ni significantly improve the cycle life, reversibility of hydrogen absorption and desorption. The diffusion process is the control step in the electrode reaction of hydrogen storage alloys.
文摘Recent development of Mg and Mg-based hydrogen storage alloys used in Ni-MH battery was discussed extensively. The results obtained from recent studies prove that these alloys with nanocrystalline/amorphous structure formed by mechanical alloying (MA) or mechanical grinding (MG) have good electrode characteristics. In general, MA or MG, and elemental substitution alloying are regarded as the effective means to seek new system of Mg-based alloys and nano-composite with improved electrode characteristics. However, until now, the currently known improvement in these electrode characteristics is still far from reach to that required for commercial application.
文摘Mg and its alloys are drawing huge attention since the last two decades as a viable option for temporary implants applications.A commendable progress has already been made in the development of these alloys.The biodegradable nature of Mg,appreciable biocompatibility of elemental Mg,and its close resemblance to natural bone in terms of density and elastic modulus make them highly preferable option amongst other available alternatives in this field.This review article presents an overview covering the recent advancements made in the field of Mg-based biodegradable implants for orthopaedic implant applications.The paper focuses on alloy development and fabrication techniques,the state of the art of important Mg-based alloy systems in terms of their mechanical properties,in-vitro and in-vivo degradation behaviour and cytotoxicity.Further,the paper reviews the current progress achieved in the clinical transition of Mg-based alloys for orthopaedic fixtures.The review also includes the degradation mechanisms of the alloys in physiological environment and highlights the mismatch existing between the rate of bone healing and alloy degradation due to rapid corrosion of the alloys in such environment,which has still restricted their widespread application.Finally,the surface coating techniques available for the alloys as an effective way to reduce the degradation rate are reviewed,followed by a discussion on the future research prospects.
基金financially supported by the National Natural Science Foundations of China(51761032 and 51871125)the Natural Science Foundations of Inner Mongolia,China(No.2019BS05005)the Scientific Research Staring Foundation of Taiyuan University of Science and Technology(20202040)
文摘The composites comprised of Co nanoparticle and C nanosheet were prepared though a high-temperature carbonization reaction.The catalysis of Co@C composites on the hydrogen storage behavior of Mg_(90)Ce_(5)Y_(5)alloy was investigated in detail by XRD,SEM,TEM,PCI,and DSC method.Because of the synergistic catalytic function of C and Co in C@Co nanocomposites,the Mg_(90)Ce_(5)Y_(5)alloy with 10 wt.%C@Co shows the excellent hydrogen absorption and desorption performances.Time for releasing hydrogen reduces from 150 min to 11 min with the addition of the C@Co composites at the temperature of 300℃.Meanwhile,the dehydrogenation activation energy also declines from 130.3 to 81.9 kJ mol^(-1)H_(2)after the addition of the C@Co composites.This positive effect attributes to the C layer with the high defect density and the Co nanoparticles,which reduces the energy barriers for the nucleation of Mg/MgH_(2)phase and the recombination of hydrogen molecule.Besides,the C@Co composites also improve the activation property of the Mg_(90)Ce_(5)Y_(5)alloy which was folly activated in the first cycle.Moreover,the temperature for initial dehydrogenation and the endothermic peak of the alloy hydride were also decreased.Although the addition of the C@Co composites increases the plateau pressures and decreases the value of the decomposition enthalpy,these differences are so small that the improvement on thermodynamics can hardly be seen.
基金H.Shao acknowledges the Macao Science and Technol-ogy Development Fund(FDCT)for funding(project no.118/2016/A3 and 0062/2018/A2)and this work was also par-tially supported by a Start-Up Research Fund from the Uni-versity of Macao(SRG2016-00088-FST)+5 种基金Q.Li also thanks the financial support from the National Natural Science Foun-dation of China(51671118)Young Elite Scientists Sponsor-ship Program by CAST(2017QNRC001)the“Chenguang”Program from the Shanghai Municipal Education Commission(17CG42)Science and Technology Committee of Shanghai(16520721800)the Program for Professor of Special Ap-pointment(Eastern Scholar)by Shanghai Municipal Educa-tion Commission(No.TP2015040).。
文摘Mg-based materials have been intensively studied for hydrogen storage applications due to their high energy density up to 2600 Wh/kg or 3700 Wh/L.However,the Mg-based materials with poor kinetics and the necessity for a high temperature to achieve 0.1 MPa hydrogen equilibrium pressure limit the applications in the onboard storage in Fuel cell vehicles(FCVs).Over the past decades,many methods have been applied to improve the hydriding/dehydriding(H/D)kinetics of Mg/MgH 2 by forming amorphous or nanosized particles,adding catalysts and employing external energy field,etc.However,which method is more effective and the intrinsic mechanism they work are widely differing versions.The hydrogenation and dehydrogenation behaviors of Mg-based alloys analyzing by kinetic models is an efficient way to reveal the H/D kinetic mechanism.However,some recently proposed models with physical meaning and simple analysis method are not known intimately by researchers.Therefore,this review focuses on the enhancement method of kinetics in Mg-based hydrogen storage materials and introduces the new kinetic models.
基金Project supported by the Competitiveness Enhancement Program of National Research Tomsk Polytechnic University(Grant No.VIU-OEF-66/2019)
文摘Mg-based hydrogen storage materials are considered to be one of the most promising solid-state hydrogen storage materials due to their large hydrogen storage capacity and low cost. However, slow hydrogen absorption/desorption rate and excessive hydrogen absorption/desorption temperature limit the application of Mg-based hydrogen storage materials.The present paper reviews the advances in the research of Mg-based hydrogen storage film in recent years, including the advantage of the film, the function theory of fabricating method and its functional theory, and the influencing factors in the technological process. The research status worldwide is introduced in detail. By comparing pure Mg, Pd-caped Mg, nonpalladium capped Mg, and Mg alloy hydrogen storage films, an ideal tendency for producing Mg-based film is pointed out,for example, looking for a cheap metal element to replace the high-priced Pd, compositing Mg film with other hydrogen storage alloy of catalytic elements, and so on.
基金The work is subsidized by the Special Funds for Major state Basic Research Projects and Project 59781001 of the National Natural Science Foundation of China.
文摘Mg-based hydrogen storage alloys are considered as a promising candidate for hydrogen system because of its lightweight, high storage capacity, low price and rich mineral resources. In detail, we reviewed the preparation and properties of Mg-Ni-based hydrogen storage alloys. All kinds of attempts have been done to improve the hydriding and dehydriding behaviors. It is found that the partial substitution of foreign elements can decrease the hydrogen absorption temperature, especially the substitution of a more electronegative element, such as AI and Mn. Mechanical alloying (MA) and mechanical grinding (MG) are the most effective methods to improve the hydriding/dehydriding kinetics and electrochemical capacity, and decrease the desorption temperature. but the corrosion resistance is so poor that the 80% of maximum capacity is lost within ten cycles. Microencapsulation is a useful measurement for improving the corrosion resistance and electrocatalytic activity. fn order to improve the properties of the alloys for practical application, the alloys should have a large number of defects, which give activated sites, subsequently, MA, MG and electroless plating should be used to improve the hydriding/dehydriding kinetics and protect the surface of alloys, respectively. The new composite Mg-based alloys give a new way for the hydrogen storage material to practical application. Furthermore we put forward several problems which will be discussed in future.
文摘Thethermal stability and the kinetics of grain growth of nanocrystalline Mg-6Al-1Zn and Mg-6Al-1Zn-1Si alloys prepared via mechanical alloying were investigated. It started with elemental powders, using a variety of analytical techniques including differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive spectrometry. The kinetics of grain growth in isothermal annealing was investigated. The XRD results show that, although the grain sizes of both material systems increase as the annealing temperature rises, the Si-containing system displays a relatively smaller grain size, i.e., 60 nm compared with 72 nm in Mg-6Al-1Zn system, after being exposed to 350 ℃ for 1 h. The second-phase intermetallic particle Mg2Si formed during the isothermal annealing of Mg-6Al-1Zn-1Si system could influence not only the activation energy but also the exponent of kinetic equation. Higher hardness values obtained in the Si-containing system would be due to the formation of Mg2Si intermetallic phase.
基金This work was financially supported by the National Natural Science Foundation of China (Nos. 50471095 and 50271008).
文摘As an example of the La-Mg-Y system, the method how to set up the themaodynamic model of individual phases was introduced in the process of thermodynamic optimization. The solution phases (liquid, body-centered cubic, face-centered cubic, hexagonal close-packed and double hexagonal close-packed) were modeled with the Redlich-Kister equation. The compound energy model has been used to describe the thermodynamic functions of the intermetallic compounds in the La-Mg-Y systems. The compounds Mg2Y, Mg24Y5, Mg12La, Mg17La2, Mg41Las, Mg3La and Mg2La in the La-Mg-Y system were treated as the formulae (Mg,Y)2(La,Mg,Y), Mg24(La,Mg,Y)4Y, Mg12(La, Y), Mg17(La,Y)2, Mg41(La,Y)5, Mg3(La,Mg,Y) and Mg2(La, Y), respectively. A model (La, Mg,Y)0.5(La,Mg,Y)0.5 was applied to describe the compound MgM formed by MgLa and MgY in order to cope with the order-disorder transition between body-centered cubic solution (A2) and MgM with CsCl-type structure (B2) in the La-Mg-Y system. The Gibbs energies of individual phases were optimized in the La-Mg, La-Y and La-Mg-Y systems by CALPHAD technique. The projection of the liquidus surfaces for the La-Mg-Y system was predicted. The Mg-based alloys database including 36 binary and 15 ternary systems formed by Mg, Al, Cu, Ni, Mn, Zn and rare earth elements was set up in SGTE standard.
基金Project supported by the Special Funds for Postdoctoral Research Project of China (No. 20060401035)the Hi-Tech Research and Development Program (863) of China (No. 2006AA11A159)
文摘Mg-25 wt% Mg2Ni composite was prepared by sintered method, hydrided at 613 K and then ball-milled with 1.5 wt% PdC12 additive for 51 h. The effects of PdCl2 on the hydriding and dehydriding behavior of Mg-25 wt% Mg2Ni composite were investigated. The absorption and desorption rate of the composite with PdCl2 is fast and the hydrogen storage capacity is more than that of the composite without PdCl2. The maximum hydrogen storage capacity reached 3.48 wt% at 373 K, and 5.05 wt% H at 453 K, respectively. The improvement of sorption and desorption kinetics is attributed to the catalytic effect of PdCl2, and the grain refining and lattice strain introduced by ball milling.
基金the National Natural Science Foundation of China(Nos.52101274,51731002)Natural Science Foundation of Shandong Province,China(Nos.ZR2020QE011,ZR2022ME089)+1 种基金Youth Top Talent Foundation of Yantai University,China(No.2219008)Graduate Innovation Foundation of Yantai University,China(No.GIFYTU2240).
文摘The Ni-coated carbon nanotubes(Ni@CNT)composite was synthesized by the facile“filtration+calcination”of Ni-based metal−organic framework(MOF)precursor and the obtained composite was used as a catalyst for MgH_(2).MgH_(2)was mixed evenly with different amounts of Ni@CNT(2.5,5.0 and 7.5,wt.%)through ball milling.The MgH_(2)−5wt.%Ni@CNT can absorb 5.2 wt.%H_(2)at 423 K in 200 s and release about 3.75 wt.%H_(2)at 573 K in 1000 s.And its dehydrogenation and rehydrogenation activation energies are reduced to 87.63 and 45.28 kJ/mol(H_(2)).The in-situ generated Mg_(2)Ni/Mg_(2)NiH4 exhibits a good catalytic effect due to the provided more diffusion channels that can be used as“hydrogen pump”.And the presence of carbon nanotubes improves the properties of MgH_(2)to some extent.
基金Supported by National Natural Science Foundation of China(Grant Nos.52001142,52005228,51801218,51911530211,51905110)Young Scientists Sponsorship Program by CAST(Grant No.2022QNRC001).
文摘This study employs advanced electrochemical and surface characterization techniques to investigate the impact of electrochemical hydrogen charging on the corrosion behavior and surface film of the Ti-6Al-4V alloy.The findings revealed the formation ofγ-TiH andδ-TiH_(2) hydrides in the alloy after hydrogen charging.Prolonging hydrogen charging resulted in more significant degradation of the alloy microstructure,leading to deteriorated protectiveness of the surface film.This trend was further confirmed by the electrochemical measurements,which showed that the corrosion resistance of the alloy progressively worsened as the hydrogen charging time was increased.Consequently,this work provides valuable insights into the mechanisms underlying the corrosion of Ti-6Al-4V alloy under hydrogen charging conditions.
基金supported by the National Key Research and Development Program of China(2022YFE03170002)the National Natural Science Foundation of China(52071286 and U2030208)the Scientific Research Fund of Zhejiang Provincial Education Department(Y202353551).
文摘Hydrogen storage alloys(HSAs)are attracting widespread interest in the nuclear industry because of the generation of stable metal hydrides after tritium absorption,thus effectively preventing the leakage of radioactive tritium.Commonly used HSAs in the hydrogen isotopes field are Zr2M(M=Co,Ni,Fe)alloys,metallic Pd,depleted U,and ZrCo alloy.Specifically,Zr2M(M=Co,Ni,Fe)alloys are considered promising tritium-getter materials,and metallic Pd is utilized to separate and purify hydrogen isotopes.Furthermore,depleted U and ZrCo alloy are well suited for storing and delivering hydrogen isotopes.Notably,all the aforementioned HSAs need to modulate their hydrogen storage properties for complex operating conditions.In this review,we present a comprehensive overview of the reported modification methods applied to the above alloys.Alloying is an effective amelioration method that mainly modulates the properties of HSAs by altering their local geometrical/electronic structures.Besides,microstructural modifications such as nano-sizing and nanopores have been used to increase the specific surface area and active sites of metallic Pd and ZrCo alloys for enhancing de-/hydrogenation kinetics.The combination of metallic Pd with support materials can significantly reduce the cost and enhance the pulverization resistance.Moreover,the poisoning resistance of ZrCo alloy is improved by constructing active surfaces with selective permeability.Overall,the review is constructive for better understanding the properties and mechanisms of hydrogen isotope storage alloys and provides effective guidance for future modification research.