Nanoconfinement is a promising approach to simultaneously enhance the thermodynamics,kinetics,and cycling stability of hydrogen storage materials.The introduction of supporting scaffolds usually causes a reduction in ...Nanoconfinement is a promising approach to simultaneously enhance the thermodynamics,kinetics,and cycling stability of hydrogen storage materials.The introduction of supporting scaffolds usually causes a reduction in the total hydrogen storage capacity due to“dead weight.”Here,we synthesize an optimized N-doped porous carbon(rN-pC)without heavy metal as supporting scaffold to confine Mg/MgH_(2) nanoparticles(Mg/MgH_(2)@rN-pC).rN-pC with 60 wt%loading capacity of Mg(denoted as 60 Mg@rN-pC)can adsorb and desorb 0.62 wt%H_(2) on the rN-pC scaffold.The nanoconfined MgH_(2) can be chemically dehydrided at 175℃,providing~3.59 wt%H_(2) with fast kinetics(fully dehydrogenated at 300℃ within 15 min).This study presents the first realization of nanoconfined Mg-based system with adsorption-active scaffolds.Besides,the nanoconfined MgH_(2) formation enthalpy is reduced to~68 kJ mol^(−1) H_(2) from~75 kJ mol^(−1) H_(2) for pure MgH_(2).The composite can be also compressed to nanostructured pellets,with volumetric H_(2) density reaching 33.4 g L^(−1) after 500 MPa compression pressure,which surpasses the 24 g L^(−1) volumetric capacity of 350 bar compressed H_(2).Our approach can be implemented to the design of hybrid H_(2) storage materials with enhanced capacity and desorption rate.展开更多
Magnesium hydride(MgH_(2))is an important material for hydrogen(H_(2))storage and transportation owing to its high capacity and reversibility.However,its intrinsic properties have considerably limited its industrial a...Magnesium hydride(MgH_(2))is an important material for hydrogen(H_(2))storage and transportation owing to its high capacity and reversibility.However,its intrinsic properties have considerably limited its industrial application.In this study,the NiFe-800 catalyst as metal-organic framework(MOF)derivative was first utilized to promote the intrinsic properties of MgH_(2).Compared to pure MgH_(2),which releases1.24 wt%H_(2)in 60 min at 275℃,the MgH_(2)-10 NiFe-800 composite releases 5.85 wt%H_(2)in the same time.Even at a lower temperature of 250℃,the MgH_(2)-10 NiFe-800 composite releases 3.57 wt%H_(2),surpassing the performance of pure MgH_(2)at 275℃.Correspondingly,while pure MgH_(2)absorbs 2.08 wt%H_(2)in60 min at 125℃,the MgH_(2)-10 NiFe-800 composite absorbs 5.35 wt%H_(2)in just 1 min,Remarkably,the MgH_(2)-10 NiFe-800 composite absorbs 2.27 wt%H_(2)in 60 min at 50℃and 4.64 wt%H_(2)at 75℃.This indicates that MgH_(2)-10 NiFe-800 exhibits optimum performance with excellent kinetics at low temperatures.Furthermore,the capacity of the MgH_(2)-10 NiFe-800 composite remains largely stable after 10cycles.Moreover,the Mg_(2)Ni/Mg_(2)NiH_(4)acts as a"hydrogen pump",providing effective diffusion channels that enhance the kinetic process of the composite during cycling.Additionally,Fe0facilitates electron transfer and creates hydrogen diffusion channels and catalytic sites.Finally,carbon(C)effectively prevents particle agglomeration and maintains the cyclic stability of the composites.Consequently,the synergistic effects of Mg_(2)Ni/Mg_(2)NiH_(4),Fe^(0),and C considerably improve the kinetic properties and cycling stability of MgH_(2).This work offers an effective and valuable approach to improving the hydrogen storage efficiency in the commercial application of MgH_(2).展开更多
Designing catalysts with high catalytic activity and stability is the key to achieve the commercial application of MgH_(2).Herein,the sulfur doped Ti_(3)C_(2)(S-Ti_(3)C_(2))was successfully prepared by heat treatment ...Designing catalysts with high catalytic activity and stability is the key to achieve the commercial application of MgH_(2).Herein,the sulfur doped Ti_(3)C_(2)(S-Ti_(3)C_(2))was successfully prepared by heat treatment of Ti_(3)C_(2)MXene under Ar/H_(2)S atmosphere to facilitate the hydrogen release and uptake from MgH_(2).The S-Ti_(3)C_(2)exhibited pleasant catalytic effect on the hydriding/dehydriding kinetics and cyclic stability of MgH_(2).The addition of 5 wt%S-Ti_(3)C_(2)into MgH_(2)resulted in a reduction of 114℃in the starting dehydriding temperature compared to pure MgH_(2).MgH_(2)+5 wt%S-Ti_(3)C_(2)sample could quickly release 6.6 wt%hydrogen in 17 min at 220℃,and 6.8 wt%H_(2)was absorbed in 25 min at 200℃.Cyclic testing revealed that MgH_(2)+5 wt%S-Ti_(3)C_(2)system achieved a reversible hydrogen capacity of 6.5 wt%.Characterization analysis demonstrated that Ti-species(Ti0,Ti^(2+),Ti-S,and Ti^(3+))as active species significantly lowered the dehydrogenation temperature and promoted the re-/dehydrogenation kinetics of MgH_(2),and sulfur doping can effectively improve the stability of Ti0 and Ti^(3+),contributing to the improvement of cyclic stability of MgH_(2).This study provides strategy for the construction of catalysts for hydrogen storage materials.展开更多
Magnesium hydride(MgH_(2))has garnered significant attention as a promising material for high-capacity hydrogen storage.However,its commercial application remains challenging due to the high operating temperature and ...Magnesium hydride(MgH_(2))has garnered significant attention as a promising material for high-capacity hydrogen storage.However,its commercial application remains challenging due to the high operating temperature and slow reaction kinetics.In this study,melt-spun Ti_(45)Cr_(40)Nb_(15)(with a BCC phase)hydride(designated as TiCrNbH_(x-)MS)was synthesized and used to form a nano-multiphase composite to improve the de-/rehydrogenation properties of MgH_(2) through ball milling.The incorporation of TiCrNbH_(x-)MS was shown to significantly enhance the hydrogen de-/rehydrogenation properties of MgH_(2).The MgH_(2)+20 wt%TiCrNbH_(x-)MS composite exhibits an appealing initial dehydrogenation temperature of 163℃ and can absorb hydrogen at room temperature.Notably,it releases 5.8 wt% hydrogen in 700 s at 230℃ and recharges 4.3 wt%hydrogen in just 2 mins at 150℃.Even after 100 cycles,it retains a reversible hydrogen capacity of 4.98 wt%.Kinetic analysis revealed that the dehydrogenation rate follows the Chou surface penetration model.Microstructural analysis showed that the FCC phase of the melt-spun TiCrNbH_(x-)MS hydride reversibly transformed into the BCC phase during the de-/rehydrogenation process in the composite.Numerous phase interfaces were generated and uniformly dispersed on the MgH_(2) surface,providing additional hydrogen diffusion pathways and heterogeneous nucleation sites for Mg/MgH_(2),thereby further improving the hydrogen de-/rehydrogenation kinetics of the system.This study offers valuable insights into the use of multiphase composites to enhance MgH_(2) performance.展开更多
The deposition of ultrafine single-atom nickel particles on Nb_(2)C(MXene)was successfully achieved using a wet chemistry method to synthesize Ni@Nb_(2)C composite.This study explored the effect of Ni@Nb_(2)C on the h...The deposition of ultrafine single-atom nickel particles on Nb_(2)C(MXene)was successfully achieved using a wet chemistry method to synthesize Ni@Nb_(2)C composite.This study explored the effect of Ni@Nb_(2)C on the hydrogen absorption and desorption properties of MgH_(2) through theoretical calculations and experimental investigations.Under the catalytic action of Ni@Nb2C,the initial dehydrogenation temperature of MgH_(2) was reduced by 121℃,with approximately 4.26 wt.% of H_(2) desorbed at 225℃ in 100 min.The dehydrogenation activation energy of the MgH_(2)+Ni@Nb_(2)C composite dropped to 86.7 kJ·mol^(-1),a reduction of 60.5 kJ·mol^(-1) compared to pure MgH_(2).Density functional theory calculations indicated that the incorporation of Ni@Nb_(2)C enhanced the performance of MgH_(2) performance by improving interactions among Nb_(2)C,Ni,Mg,and H atoms.In the Ni@Nb_(2)C+MgH_(2) system,the lengths of Mg-H bonds(1.91-1.99 A)were found to be longer than those observed in pure MgH_(2)(1.71 A).The dehydrogenation energy for this system(1.08 eV)was lower than that for Nb_(2)C(1.52 eV).These findings suggest that the synergistic effect of Ni and Nb2C significantly enhances the hydrogenation/dehydrogenation kinetics of MgH_(2),thereby introducing a novel approach for catalytic modification of solid hydrogen storage materials through synergistic actions.展开更多
The role of catalysts in enhancing the hydrogen storage kinetics of the Mg/MgH_(2)system is pivotal.However,the exploration of efficient catalysts and the underlying principles of their design remain both a prominent ...The role of catalysts in enhancing the hydrogen storage kinetics of the Mg/MgH_(2)system is pivotal.However,the exploration of efficient catalysts and the underlying principles of their design remain both a prominent focus and a significant challenge in current research.In this study,we present a bimetallic oxide of Bi_(2)Ti_(2)O_(7)hollow sphere as a highly effective catalyst for MgH_(2).As a result,the Bi_(2)Ti_(2)O_(7)-catalyzed Mg/MgH_(2)system lowers the hydrogen desorption initiation temperature to 194.3℃,reduces the peak desorption temperature to 245.6℃,decreases the dehydrogenation activation energy to 82.14 kJ·mol^(−1),and can absorb 5.4 wt.%of hydrogen within 60 s at 200℃,demonstrating outstanding hydrogen ab/desorption kinetics,compared to pure MgH_(2).Additionally,it can maintain a high hydrogen capacity of 5.2 wt.%,even after 50 dehydrogenation cycles,showing good cycle stability.The characterization results show that the high-valent Bi and Ti in Bi_(2)Ti_(2)O_(7)are reduced to their low-valent or even zero-valent metallic states during the dehydrogenation and hydrogenation process,thus establishing an in-situ multivalent and multi-element catalytic environment.Density functional theory calculations further reveal that the synergistic effects between Bi and Ti in the Bi-Ti mixed oxide facilitate the cleavage of Mg-H bonds and lower the kinetic barrier for the dissociation of hydrogen molecules,thereby substantially enhancing the kinetics of the Mg/MgH_(2)system.This study presents a strategic method for developing efficient catalysts for hydrogen storage materials by harnessing the synergistic effects of metal elements.展开更多
Metallic single-atom catalysts(SACs)have demonstrated high activity and potential in enhancing the hydrogen storage properties of MgH_(2).However,previous reports primarily focus on supported SACs,which often suffer f...Metallic single-atom catalysts(SACs)have demonstrated high activity and potential in enhancing the hydrogen storage properties of MgH_(2).However,previous reports primarily focus on supported SACs,which often suffer from insufficient co ntact between single-atom active sites and hydrogen storage materials.In this study,the precursor Mo(CO)_(6)is uniformly dispersed on the surface of MgH_(2)via impregnation adsorption,leading to the formation of alloy-type Mo single atoms after hydrogenation/dehydrogenation activation.This alloy structure enables zero-distance contact between catalytic sites and the hydrogen storage material,facilitating electron exchange and hydrogen transfer between the Mo sites and MgH_(2).The MgH_(2)loaded with Mo single atoms(Mo_(1)-MgH_(2))exhibits excellent hydrogen absorption and desorption properties,with the initial hydrogen release temperature lowered from 323 to 218℃.At 250℃,Mo_(1)-MgH_(2)absorbs over 6.77 wt% of hydrogen within 1 min and releases over 5.85 wt% within 4 h.During 10 cycles of hydrogenation and dehydrogenation reactions,Mo_(1)-MgH_(2)maintains nearly 100% capacity and shows stable kinetics.This work provides new insights into the design and fabrication of catalysts for hydrogen storage materials.展开更多
Magnesium-based hydrogen storage materials,such as MgH_(2),have attracted considerable attention because of its superior hydrogen storage capacities,inexpensive,and excellent reversibility.However,their high thermodyn...Magnesium-based hydrogen storage materials,such as MgH_(2),have attracted considerable attention because of its superior hydrogen storage capacities,inexpensive,and excellent reversibility.However,their high thermodynamic stabilities and slow kinetics lead to relatively high desorption temperatures,which severely limit the wide application of MgH_(2).In this study,the inclusion of vanadium induced the formation Ni-Co metal-organic frameworks(MOF)from a NiCo layered double hydroxide(LDH),thereby increasing the number of defects and vacancies,and improving the hydrogen storage properties of MgH_(2).The synthesized NiCo-MOF/V-O-doped MgH_(2) system demonstrates excellent hydrogen storage capacity.More specifically,5 wt.%of H_(2) was released over 20 min at a relatively low dehydrogenation temperature of 250℃,and almost complete dehydrogenation was achieved at 300℃ for 5 min.In addition,at 125℃,the hydrogen storage material absorbed 5.5 wt.%H_(2) in 10 min.Furthermore,the activation energy of dehydrogenation was determined to be 69.588±6.302 k J·mol^(-1)which is significantly lower than that of the ball-milled MgH_(2)(i.e.,118.649±2.825 kJ·mol^(-1)).It was therefore inferred that during dehydrogenation process,a Mg_(2)Ni/Mg_(2) NiH_4 hydrogen pump is formed by Ni,while the V-H and Co-H bonds formed by Co and V during the reaction act synergistically to catalyze the absorption and desorption of hydrogen,thereby increasing the hydrogen storage capacity of MgH_(2).These experiments provide new perspectives on the commercial application of MgH_(2).展开更多
MgH_(2)is a promising solid-state hydrogen storage material;one of the limitations of its scale-application is the slow rate of hydrogen uptake and release.The addition of catalyst to improve the kinetics of MgH_(2)ha...MgH_(2)is a promising solid-state hydrogen storage material;one of the limitations of its scale-application is the slow rate of hydrogen uptake and release.The addition of catalyst to improve the kinetics of MgH_(2)has achieved remarkable results.However,these studies require high-speed ball milling(400-500 rpm)to achieve the combination of MgH_(2)and catalyst,and such harsh processing conditions are difficult to achieve in industrial production.In this work,the catalyst and MgH_(2)were efficiently combined at lower milling speed(300 rpm)by introducing tetrahydrofuran C4H8O(THF)as an auxiliary agent.Moreover,milling with THF promotes the nanocrystallization of MgH_(2),which further improves its performance.Results show that THF-assisted MgH_(2)absorbed 6.1 wt%at 90℃and desorbed 6.1 wt%at 275℃,while the MgH_(2)milling under the same speed without THF cannot absorb hydrogen and only desorbed 3.3 wt%.It reveals that the synergistic effect produced by nano-crystallization and nano-hydrogen pump is the key mechanism of improving the performance of MgH_(2)after introducing THF.This work proposes a novel synergistic strategy for modifying MgH_(2),offering practical insights for enhancing its hydrogen storage performance under low-speed ball milling.展开更多
MgH_(2)与水反应产生大量氢气有利于氢能源在燃料电池领域的发展,但产氢速率慢及Mg(OH)_(2)致密层这一关键问题限制了其应用。本文采用浓度分别为0.3、0.9、1.7、2.5 mol/L的海盐溶液与0.1 g MgH_(2)进行多次水解实验,测定不同温度下的...MgH_(2)与水反应产生大量氢气有利于氢能源在燃料电池领域的发展,但产氢速率慢及Mg(OH)_(2)致密层这一关键问题限制了其应用。本文采用浓度分别为0.3、0.9、1.7、2.5 mol/L的海盐溶液与0.1 g MgH_(2)进行多次水解实验,测定不同温度下的水解动力学曲线;采用XRD和SEM扫描技术对水解产物进行物相和形貌分析,并讨论了水解机制以及不同浓度的海盐溶液对颗粒表面的影响;通过Avrami-Erofeev和Arrhenius公式线性拟合分析了水解动力学过程和活化能。研究发现:浓度为0.9 mol/L的海盐溶液与0.1 g MgH_(2)反应时的水解性能以及表观活性改善最佳,在高温下,0.3、0.9、1.7、2.5 mol/L海盐溶液的水解活化能分别测定为(33.1±0.4)、(26.1±0.5)、(36.3±0.8)、(40.1±0.2)kJ/mol,水解产氢速率最快分别为11.33、12、10.66、11.33 mL/(g·s),确定了浓度对水解动力学的影响。MgH_(2)的这些优异的水解性能对镁基合金的水解研究具有重要意义。展开更多
Mg/MgH_(2) has garnered significant attention primarily due to its abundant availability and high gravimetric density.Nevertheless,its practical implementation hindered by its high thermodynamic stability and sluggish...Mg/MgH_(2) has garnered significant attention primarily due to its abundant availability and high gravimetric density.Nevertheless,its practical implementation hindered by its high thermodynamic stability and sluggish kinetics.Fortunately,the introduction of transition metal single atom(TM SA)catalysts has emerged as an effective method to enhance the hydrogen storage properties of Mg/MgH_(2).Among these catalysts,the synergistic effect of nanoconfinement and TM SAs plays a pivotal role in the hydriding/dehydriding kinetics of Mg/MgH_(2).However,the effects of varying TM SAs interacting with N modified confined materials on H_(2) adsorption and desorption and underlying mechanisms remain enigmatic.Leveraging DFT calculations,we investigated the potential of combining TM SA catalysts with N-modified Carbon nanomaterials(CNT)to enhance the hydrogenation/dehydrogenation of Mg/MgH_(2).TM SA N-CNTs-Mg/MgH_(2) heterojunction systems encompassing ten 3d/4d transition metals were designed and constructed.We systematically investigated the impact of TM SA N-CNTs on the hydrogen absorption and desorption properties of Mg/MgH_(2) by examining parameters such as the electronic localization function(ELF),distorted charge density distributions,adsorption energies,dissociation energies,electronegativity,and the D-band center.Notably,the energy barriers for Mg/MgH_(2) hydrogenation and dehydrogenation were significantly reduced by 0.2-0.7 eV and 1.6-2.2 eV,respectively,through the catalytic promotion of TM SA N-CNTs.Herein,a novel“electronic-ropeway”effect was proposed to elucidate the underlying mechanism responsible for enhancing the hydrogen absorption and desorption kinetics in Mg/MgH_(2).Specifically,the contribution degree of TM SA N-CNTs and system electronegativity emerged as effective descriptors for predicting the reduced hydrogenation/dehydrogenation energy barriers.It is anticipated that elucidating the role of TM SA-N-CNTs will pave the way for developing innovative strategies to enhance the hydrogen absorption and desorption kinetics of Mg/MgH_(2) systems,thereby providing valuable design principles for the construction of novel Mg/MgH_(2) hydrogen storage materials.展开更多
Hydrogen is considered one of the most ideal future energy carriers.The safe storage and convenient transportation of hydrogen are key factors for the utilization of hydrogen energy.In the current investigation,two-di...Hydrogen is considered one of the most ideal future energy carriers.The safe storage and convenient transportation of hydrogen are key factors for the utilization of hydrogen energy.In the current investigation,two-dimensional vanadium carbide(VC) was prepared by an etching method using V_(4)AlC_(3) as a precursor and then employed to enhance the hydrogen storage properties of MgH_(2).The studied results indicate that VC-doped MgH_(2) can absorb hydrogen at room temperature and release hydrogen at 170℃. Moreover,it absorbs 5.0 wt.%of H_(2) within 9.8 min at 100℃ and desorbs 5.0 wt.% of H_(2) within 3.2 min at 300℃.The dehydrogenation apparent activation energy of VC-doped MgH_(2) is 89.3 ± 2.8 kJ/mol,which is far lower than that of additive-free MgH_(2)(138.5 ± 2.4 kJ/mol),respectively.Ab-initio simulations showed that VC can stretch Mg-H bonds and make the Mg-H bonds easier to break,which is responsible for the decrease of dehydrogenation temperature and conducive to accelerating the diffusion rate of hydrogen atoms,thus,the hydrogen storage properties of MgH_(2) are remarkable improved through addition of VC.展开更多
基金supported by the National Key R&D Program of China(2022YFB3803700)National Natural Science Foundation of China(52171186)+1 种基金Young Elite Scientists Sponsorship Program by CAST(2023QNRC001)support from“Zhiyuan Honor Program”for doctoral students,Shanghai Jiao Tong University.
文摘Nanoconfinement is a promising approach to simultaneously enhance the thermodynamics,kinetics,and cycling stability of hydrogen storage materials.The introduction of supporting scaffolds usually causes a reduction in the total hydrogen storage capacity due to“dead weight.”Here,we synthesize an optimized N-doped porous carbon(rN-pC)without heavy metal as supporting scaffold to confine Mg/MgH_(2) nanoparticles(Mg/MgH_(2)@rN-pC).rN-pC with 60 wt%loading capacity of Mg(denoted as 60 Mg@rN-pC)can adsorb and desorb 0.62 wt%H_(2) on the rN-pC scaffold.The nanoconfined MgH_(2) can be chemically dehydrided at 175℃,providing~3.59 wt%H_(2) with fast kinetics(fully dehydrogenated at 300℃ within 15 min).This study presents the first realization of nanoconfined Mg-based system with adsorption-active scaffolds.Besides,the nanoconfined MgH_(2) formation enthalpy is reduced to~68 kJ mol^(−1) H_(2) from~75 kJ mol^(−1) H_(2) for pure MgH_(2).The composite can be also compressed to nanostructured pellets,with volumetric H_(2) density reaching 33.4 g L^(−1) after 500 MPa compression pressure,which surpasses the 24 g L^(−1) volumetric capacity of 350 bar compressed H_(2).Our approach can be implemented to the design of hybrid H_(2) storage materials with enhanced capacity and desorption rate.
基金financially supported by the Natural Science Foundation of Guangdong province(2024A1515010228)the Research and demonstration application of intelligent sensing technology for lithium ion battery energy storage(SPICXJ-HTBBC-2022-01).
文摘Magnesium hydride(MgH_(2))is an important material for hydrogen(H_(2))storage and transportation owing to its high capacity and reversibility.However,its intrinsic properties have considerably limited its industrial application.In this study,the NiFe-800 catalyst as metal-organic framework(MOF)derivative was first utilized to promote the intrinsic properties of MgH_(2).Compared to pure MgH_(2),which releases1.24 wt%H_(2)in 60 min at 275℃,the MgH_(2)-10 NiFe-800 composite releases 5.85 wt%H_(2)in the same time.Even at a lower temperature of 250℃,the MgH_(2)-10 NiFe-800 composite releases 3.57 wt%H_(2),surpassing the performance of pure MgH_(2)at 275℃.Correspondingly,while pure MgH_(2)absorbs 2.08 wt%H_(2)in60 min at 125℃,the MgH_(2)-10 NiFe-800 composite absorbs 5.35 wt%H_(2)in just 1 min,Remarkably,the MgH_(2)-10 NiFe-800 composite absorbs 2.27 wt%H_(2)in 60 min at 50℃and 4.64 wt%H_(2)at 75℃.This indicates that MgH_(2)-10 NiFe-800 exhibits optimum performance with excellent kinetics at low temperatures.Furthermore,the capacity of the MgH_(2)-10 NiFe-800 composite remains largely stable after 10cycles.Moreover,the Mg_(2)Ni/Mg_(2)NiH_(4)acts as a"hydrogen pump",providing effective diffusion channels that enhance the kinetic process of the composite during cycling.Additionally,Fe0facilitates electron transfer and creates hydrogen diffusion channels and catalytic sites.Finally,carbon(C)effectively prevents particle agglomeration and maintains the cyclic stability of the composites.Consequently,the synergistic effects of Mg_(2)Ni/Mg_(2)NiH_(4),Fe^(0),and C considerably improve the kinetic properties and cycling stability of MgH_(2).This work offers an effective and valuable approach to improving the hydrogen storage efficiency in the commercial application of MgH_(2).
基金supported by the National Natural Science Foundation of China(U22A20120,52071135,51871090,U1804135,and 52301269)the Natural Science Foundation of Hebei Province for Innovation Groups Program(C2022203003)Fundamental Research Funds for the Universities of Henan Province(NSFRF220201).
文摘Designing catalysts with high catalytic activity and stability is the key to achieve the commercial application of MgH_(2).Herein,the sulfur doped Ti_(3)C_(2)(S-Ti_(3)C_(2))was successfully prepared by heat treatment of Ti_(3)C_(2)MXene under Ar/H_(2)S atmosphere to facilitate the hydrogen release and uptake from MgH_(2).The S-Ti_(3)C_(2)exhibited pleasant catalytic effect on the hydriding/dehydriding kinetics and cyclic stability of MgH_(2).The addition of 5 wt%S-Ti_(3)C_(2)into MgH_(2)resulted in a reduction of 114℃in the starting dehydriding temperature compared to pure MgH_(2).MgH_(2)+5 wt%S-Ti_(3)C_(2)sample could quickly release 6.6 wt%hydrogen in 17 min at 220℃,and 6.8 wt%H_(2)was absorbed in 25 min at 200℃.Cyclic testing revealed that MgH_(2)+5 wt%S-Ti_(3)C_(2)system achieved a reversible hydrogen capacity of 6.5 wt%.Characterization analysis demonstrated that Ti-species(Ti0,Ti^(2+),Ti-S,and Ti^(3+))as active species significantly lowered the dehydrogenation temperature and promoted the re-/dehydrogenation kinetics of MgH_(2),and sulfur doping can effectively improve the stability of Ti0 and Ti^(3+),contributing to the improvement of cyclic stability of MgH_(2).This study provides strategy for the construction of catalysts for hydrogen storage materials.
基金financially supported by the National Key Research and Development program of China(2022YFB3504700)the National Natural Science Foundation of China(U23A20128)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA0400304)the Research Projects of Ganjiang Innovation Academy,Chinese Academy of Sciences(No.E355B0020).
文摘Magnesium hydride(MgH_(2))has garnered significant attention as a promising material for high-capacity hydrogen storage.However,its commercial application remains challenging due to the high operating temperature and slow reaction kinetics.In this study,melt-spun Ti_(45)Cr_(40)Nb_(15)(with a BCC phase)hydride(designated as TiCrNbH_(x-)MS)was synthesized and used to form a nano-multiphase composite to improve the de-/rehydrogenation properties of MgH_(2) through ball milling.The incorporation of TiCrNbH_(x-)MS was shown to significantly enhance the hydrogen de-/rehydrogenation properties of MgH_(2).The MgH_(2)+20 wt%TiCrNbH_(x-)MS composite exhibits an appealing initial dehydrogenation temperature of 163℃ and can absorb hydrogen at room temperature.Notably,it releases 5.8 wt% hydrogen in 700 s at 230℃ and recharges 4.3 wt%hydrogen in just 2 mins at 150℃.Even after 100 cycles,it retains a reversible hydrogen capacity of 4.98 wt%.Kinetic analysis revealed that the dehydrogenation rate follows the Chou surface penetration model.Microstructural analysis showed that the FCC phase of the melt-spun TiCrNbH_(x-)MS hydride reversibly transformed into the BCC phase during the de-/rehydrogenation process in the composite.Numerous phase interfaces were generated and uniformly dispersed on the MgH_(2) surface,providing additional hydrogen diffusion pathways and heterogeneous nucleation sites for Mg/MgH_(2),thereby further improving the hydrogen de-/rehydrogenation kinetics of the system.This study offers valuable insights into the use of multiphase composites to enhance MgH_(2) performance.
基金financially supported by the National Natural Science Foundation of China under Grant numbers 22379030,52001079 and 52261038the Guangxi Key Laboratory of Green Manufacturing for Ecological Aluminum Industry(GXGMEA2024)the Nanning Excellent Young Talents Cultivation Project for Scientific and Technological Innovation and Entrepreneurship(RC20220102).
文摘The deposition of ultrafine single-atom nickel particles on Nb_(2)C(MXene)was successfully achieved using a wet chemistry method to synthesize Ni@Nb_(2)C composite.This study explored the effect of Ni@Nb_(2)C on the hydrogen absorption and desorption properties of MgH_(2) through theoretical calculations and experimental investigations.Under the catalytic action of Ni@Nb2C,the initial dehydrogenation temperature of MgH_(2) was reduced by 121℃,with approximately 4.26 wt.% of H_(2) desorbed at 225℃ in 100 min.The dehydrogenation activation energy of the MgH_(2)+Ni@Nb_(2)C composite dropped to 86.7 kJ·mol^(-1),a reduction of 60.5 kJ·mol^(-1) compared to pure MgH_(2).Density functional theory calculations indicated that the incorporation of Ni@Nb_(2)C enhanced the performance of MgH_(2) performance by improving interactions among Nb_(2)C,Ni,Mg,and H atoms.In the Ni@Nb_(2)C+MgH_(2) system,the lengths of Mg-H bonds(1.91-1.99 A)were found to be longer than those observed in pure MgH_(2)(1.71 A).The dehydrogenation energy for this system(1.08 eV)was lower than that for Nb_(2)C(1.52 eV).These findings suggest that the synergistic effect of Ni and Nb2C significantly enhances the hydrogenation/dehydrogenation kinetics of MgH_(2),thereby introducing a novel approach for catalytic modification of solid hydrogen storage materials through synergistic actions.
基金supported by the National Key Research and Development Program of China(No.2024YFB4007204,2022YFB4004301)the National Natural Science Founda-tion of China(Grant Nos.52477220,52301287,22005353)+2 种基金the Two-chain Integration Key Project of Shaanxi Province(2021LLRH-09)the Key Research and Development Program of Shaanxi Province(No.2024CY2-GJHX-44,2024CY2-GJHX-53,2024GX-ZDCYL-04-06)the Key Industrial Chain Technology Research Program of Xi’an city(23LL-RHZDZX0017).
文摘The role of catalysts in enhancing the hydrogen storage kinetics of the Mg/MgH_(2)system is pivotal.However,the exploration of efficient catalysts and the underlying principles of their design remain both a prominent focus and a significant challenge in current research.In this study,we present a bimetallic oxide of Bi_(2)Ti_(2)O_(7)hollow sphere as a highly effective catalyst for MgH_(2).As a result,the Bi_(2)Ti_(2)O_(7)-catalyzed Mg/MgH_(2)system lowers the hydrogen desorption initiation temperature to 194.3℃,reduces the peak desorption temperature to 245.6℃,decreases the dehydrogenation activation energy to 82.14 kJ·mol^(−1),and can absorb 5.4 wt.%of hydrogen within 60 s at 200℃,demonstrating outstanding hydrogen ab/desorption kinetics,compared to pure MgH_(2).Additionally,it can maintain a high hydrogen capacity of 5.2 wt.%,even after 50 dehydrogenation cycles,showing good cycle stability.The characterization results show that the high-valent Bi and Ti in Bi_(2)Ti_(2)O_(7)are reduced to their low-valent or even zero-valent metallic states during the dehydrogenation and hydrogenation process,thus establishing an in-situ multivalent and multi-element catalytic environment.Density functional theory calculations further reveal that the synergistic effects between Bi and Ti in the Bi-Ti mixed oxide facilitate the cleavage of Mg-H bonds and lower the kinetic barrier for the dissociation of hydrogen molecules,thereby substantially enhancing the kinetics of the Mg/MgH_(2)system.This study presents a strategic method for developing efficient catalysts for hydrogen storage materials by harnessing the synergistic effects of metal elements.
基金supported by the Science and Technology Foundation of China Electric Power Research Institute(Development of high-energy-density alloy solid hydrogen storage materials,DG8323-002)。
文摘Metallic single-atom catalysts(SACs)have demonstrated high activity and potential in enhancing the hydrogen storage properties of MgH_(2).However,previous reports primarily focus on supported SACs,which often suffer from insufficient co ntact between single-atom active sites and hydrogen storage materials.In this study,the precursor Mo(CO)_(6)is uniformly dispersed on the surface of MgH_(2)via impregnation adsorption,leading to the formation of alloy-type Mo single atoms after hydrogenation/dehydrogenation activation.This alloy structure enables zero-distance contact between catalytic sites and the hydrogen storage material,facilitating electron exchange and hydrogen transfer between the Mo sites and MgH_(2).The MgH_(2)loaded with Mo single atoms(Mo_(1)-MgH_(2))exhibits excellent hydrogen absorption and desorption properties,with the initial hydrogen release temperature lowered from 323 to 218℃.At 250℃,Mo_(1)-MgH_(2)absorbs over 6.77 wt% of hydrogen within 1 min and releases over 5.85 wt% within 4 h.During 10 cycles of hydrogenation and dehydrogenation reactions,Mo_(1)-MgH_(2)maintains nearly 100% capacity and shows stable kinetics.This work provides new insights into the design and fabrication of catalysts for hydrogen storage materials.
基金supported by the National Natural Science Foundation of China(Grant Nos.U24A2044,52071092).
文摘Magnesium-based hydrogen storage materials,such as MgH_(2),have attracted considerable attention because of its superior hydrogen storage capacities,inexpensive,and excellent reversibility.However,their high thermodynamic stabilities and slow kinetics lead to relatively high desorption temperatures,which severely limit the wide application of MgH_(2).In this study,the inclusion of vanadium induced the formation Ni-Co metal-organic frameworks(MOF)from a NiCo layered double hydroxide(LDH),thereby increasing the number of defects and vacancies,and improving the hydrogen storage properties of MgH_(2).The synthesized NiCo-MOF/V-O-doped MgH_(2) system demonstrates excellent hydrogen storage capacity.More specifically,5 wt.%of H_(2) was released over 20 min at a relatively low dehydrogenation temperature of 250℃,and almost complete dehydrogenation was achieved at 300℃ for 5 min.In addition,at 125℃,the hydrogen storage material absorbed 5.5 wt.%H_(2) in 10 min.Furthermore,the activation energy of dehydrogenation was determined to be 69.588±6.302 k J·mol^(-1)which is significantly lower than that of the ball-milled MgH_(2)(i.e.,118.649±2.825 kJ·mol^(-1)).It was therefore inferred that during dehydrogenation process,a Mg_(2)Ni/Mg_(2) NiH_4 hydrogen pump is formed by Ni,while the V-H and Co-H bonds formed by Co and V during the reaction act synergistically to catalyze the absorption and desorption of hydrogen,thereby increasing the hydrogen storage capacity of MgH_(2).These experiments provide new perspectives on the commercial application of MgH_(2).
基金financially supported by the Natural Science Foundation of Zhejiang Province(No.LQ24E010003)the Baima Lake Laboratory Joint Funds of the Zhejiang Provincial Natural Science Foundation of China(Nos.LBMHY24E060004,LBMHY24E060005)
文摘MgH_(2)is a promising solid-state hydrogen storage material;one of the limitations of its scale-application is the slow rate of hydrogen uptake and release.The addition of catalyst to improve the kinetics of MgH_(2)has achieved remarkable results.However,these studies require high-speed ball milling(400-500 rpm)to achieve the combination of MgH_(2)and catalyst,and such harsh processing conditions are difficult to achieve in industrial production.In this work,the catalyst and MgH_(2)were efficiently combined at lower milling speed(300 rpm)by introducing tetrahydrofuran C4H8O(THF)as an auxiliary agent.Moreover,milling with THF promotes the nanocrystallization of MgH_(2),which further improves its performance.Results show that THF-assisted MgH_(2)absorbed 6.1 wt%at 90℃and desorbed 6.1 wt%at 275℃,while the MgH_(2)milling under the same speed without THF cannot absorb hydrogen and only desorbed 3.3 wt%.It reveals that the synergistic effect produced by nano-crystallization and nano-hydrogen pump is the key mechanism of improving the performance of MgH_(2)after introducing THF.This work proposes a novel synergistic strategy for modifying MgH_(2),offering practical insights for enhancing its hydrogen storage performance under low-speed ball milling.
文摘MgH_(2)与水反应产生大量氢气有利于氢能源在燃料电池领域的发展,但产氢速率慢及Mg(OH)_(2)致密层这一关键问题限制了其应用。本文采用浓度分别为0.3、0.9、1.7、2.5 mol/L的海盐溶液与0.1 g MgH_(2)进行多次水解实验,测定不同温度下的水解动力学曲线;采用XRD和SEM扫描技术对水解产物进行物相和形貌分析,并讨论了水解机制以及不同浓度的海盐溶液对颗粒表面的影响;通过Avrami-Erofeev和Arrhenius公式线性拟合分析了水解动力学过程和活化能。研究发现:浓度为0.9 mol/L的海盐溶液与0.1 g MgH_(2)反应时的水解性能以及表观活性改善最佳,在高温下,0.3、0.9、1.7、2.5 mol/L海盐溶液的水解活化能分别测定为(33.1±0.4)、(26.1±0.5)、(36.3±0.8)、(40.1±0.2)kJ/mol,水解产氢速率最快分别为11.33、12、10.66、11.33 mL/(g·s),确定了浓度对水解动力学的影响。MgH_(2)的这些优异的水解性能对镁基合金的水解研究具有重要意义。
基金financed by the National Key Research and Development Program of China [grants number 2023YFB3809101]the National Natural Science Foundation of China [grants number 52471225, 52271212, 52201250]+1 种基金the Natural Science Foundation of Hebei Province [grants number E2018502054]the Fundamental Research Funds for the Central Universities [grants number 2023MS148]
文摘Mg/MgH_(2) has garnered significant attention primarily due to its abundant availability and high gravimetric density.Nevertheless,its practical implementation hindered by its high thermodynamic stability and sluggish kinetics.Fortunately,the introduction of transition metal single atom(TM SA)catalysts has emerged as an effective method to enhance the hydrogen storage properties of Mg/MgH_(2).Among these catalysts,the synergistic effect of nanoconfinement and TM SAs plays a pivotal role in the hydriding/dehydriding kinetics of Mg/MgH_(2).However,the effects of varying TM SAs interacting with N modified confined materials on H_(2) adsorption and desorption and underlying mechanisms remain enigmatic.Leveraging DFT calculations,we investigated the potential of combining TM SA catalysts with N-modified Carbon nanomaterials(CNT)to enhance the hydrogenation/dehydrogenation of Mg/MgH_(2).TM SA N-CNTs-Mg/MgH_(2) heterojunction systems encompassing ten 3d/4d transition metals were designed and constructed.We systematically investigated the impact of TM SA N-CNTs on the hydrogen absorption and desorption properties of Mg/MgH_(2) by examining parameters such as the electronic localization function(ELF),distorted charge density distributions,adsorption energies,dissociation energies,electronegativity,and the D-band center.Notably,the energy barriers for Mg/MgH_(2) hydrogenation and dehydrogenation were significantly reduced by 0.2-0.7 eV and 1.6-2.2 eV,respectively,through the catalytic promotion of TM SA N-CNTs.Herein,a novel“electronic-ropeway”effect was proposed to elucidate the underlying mechanism responsible for enhancing the hydrogen absorption and desorption kinetics in Mg/MgH_(2).Specifically,the contribution degree of TM SA N-CNTs and system electronegativity emerged as effective descriptors for predicting the reduced hydrogenation/dehydrogenation energy barriers.It is anticipated that elucidating the role of TM SA-N-CNTs will pave the way for developing innovative strategies to enhance the hydrogen absorption and desorption kinetics of Mg/MgH_(2) systems,thereby providing valuable design principles for the construction of novel Mg/MgH_(2) hydrogen storage materials.
基金supported by the National Natural Science Foundation of China (Grant Nos.52261038 and 51861002)the Natural Science Foundation of Guangxi Province (Grant No.2018GXNSFAA294125)+1 种基金the Innovation-driven Development Foundation of Guangxi Province (Grant No.AA17204063)support by the Ministry of Science and Higher Education of the Russian Federation in the framework of the Increase Competitiveness Program of NUST "MISiS" (grant number K2-2020-046)。
文摘Hydrogen is considered one of the most ideal future energy carriers.The safe storage and convenient transportation of hydrogen are key factors for the utilization of hydrogen energy.In the current investigation,two-dimensional vanadium carbide(VC) was prepared by an etching method using V_(4)AlC_(3) as a precursor and then employed to enhance the hydrogen storage properties of MgH_(2).The studied results indicate that VC-doped MgH_(2) can absorb hydrogen at room temperature and release hydrogen at 170℃. Moreover,it absorbs 5.0 wt.%of H_(2) within 9.8 min at 100℃ and desorbs 5.0 wt.% of H_(2) within 3.2 min at 300℃.The dehydrogenation apparent activation energy of VC-doped MgH_(2) is 89.3 ± 2.8 kJ/mol,which is far lower than that of additive-free MgH_(2)(138.5 ± 2.4 kJ/mol),respectively.Ab-initio simulations showed that VC can stretch Mg-H bonds and make the Mg-H bonds easier to break,which is responsible for the decrease of dehydrogenation temperature and conducive to accelerating the diffusion rate of hydrogen atoms,thus,the hydrogen storage properties of MgH_(2) are remarkable improved through addition of VC.
