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
La-Mg-Ni-based hydrogen storage alloys with superlattice structures are the new generation anode material for nickel metal hydride(Ni-MH)batteries owing to the advantages of high capacity and exceptional activation pr...La-Mg-Ni-based hydrogen storage alloys with superlattice structures are the new generation anode material for nickel metal hydride(Ni-MH)batteries owing to the advantages of high capacity and exceptional activation properties.However,the cycling stability is not currently satisfactory enough which plagues its application.Herein,a strategy of partially substituting La with the Y element is proposed to boost the capacity durability of La-Mg-Ni-based alloys.Furthermore,phase structure regulation is implemented simultaneously to obtain the A5 B19-type alloy with good crystal stability specifically.It is found that Y promotes the phase formation of the Pr5 Co19-type phase after annealing at 985℃.The alloy containing Y contributes to the superior rate capability resulting from the promoted hydrogen diffusion rate.Notably,Y substitution enables strengthening the anti-pulverization ability of the alloy in terms of increasing the volume match between[A_(2)B_(4)]and[AB5]subunits,and effectively enhances the anti-corrosion ability of the alloy due to high electronegativity,realizing improved long-term cycling stability of the alloy from 74.2%to 78.5%after cycling 300 times.The work is expected to shed light on the composition and structure design of the La-Mg-Ni-based hydrogen storage alloy for Ni-MH batteries.展开更多
Rare earth-Mg-Ni-based alloys with superlattice structures are new generation negative electrode materials for the nickel metal hydride batteries.Among them,the novel AB_(4)-type superlattice structure alloy is suppos...Rare earth-Mg-Ni-based alloys with superlattice structures are new generation negative electrode materials for the nickel metal hydride batteries.Among them,the novel AB_(4)-type superlattice structure alloy is supposed to have superior cycling stability and rate capability.Yet its preparation is hindered by the crucial requirement of temperature and the special composition which is close to the other superlattice structure.Here,we prepare rare earth-Mg-Ni-based alloy and study the phase transformation of alloys to make clear the formation of AB_(4)-type phase.It is found Pr_(5)Co_(19)-type phase is converted from Ce_(5)Co_(19)-type phase and shows good stability at higher temperature compared to the Ce_(5)Co_(19)-type phase in the range of 930-970℃.Afterwards,with further 5℃increasing,AB_(4)-type superlattice structure forms at a temperature of 975℃by consuming Pr_(5)Co_(19)-type phase.In contrast with A_(5)B_(19)-type alloy,AB_(4)-type alloy has superior rate capability owing to the dominant advantages of charge transfer and hydrogen diffusion.Besides,AB_(4)-type alloy shows long lifespan whose capacity retention rates are 89.2%at the 100;cycle and 82.8%at the 200;cycle,respectively.AB_(4)-type alloy delivers 1.53 wt.%hydrogen storage capacity at room temperature and exhibits higher plateau pressure than Pr_(5)Co_(19)-type alloy.The work provides novel AB_(4)-type alloy with preferable electrochemical performance as negative electrode material to inspire the development of nickel metal hydride batteries.展开更多
In this work,a Mg-based composite material with in-situ formed LaH3, Mg2 NiH4-LiBH4 ＋ 20 wt% LaH3,was prepared by ball milling LiBH4 and hydrogenated LaMg2 Ni and Mg2 Ni powder mixture, followed by heat treatment at ...In this work,a Mg-based composite material with in-situ formed LaH3, Mg2 NiH4-LiBH4 ＋ 20 wt% LaH3,was prepared by ball milling LiBH4 and hydrogenated LaMg2 Ni and Mg2 Ni powder mixture, followed by heat treatment at 573 K. The onset dehydrogenation temperature of the composite is reduced by 50 K compared with that of Mg2 NiH4-LiBH4. The LaH3-doped composite shows faster kinetics,absorbing1.43 wt% hydrogen within 100 s at 423 K,which is 6.5 times faster than Mg2 NiH4-LiBH4. Moreover,the composite releases 1.24 wt% hydrogen within 500 s at 573 K,0.69 wt% higher than Mg2 NiH4-LiBH4. The activation energy of the composite is reduced by 8.2 and 80 kJ/mol compared with that of Mg2 NiH4-LiBH4 and commercial MgH2, respectively. The improvement in hydrogen storage properties is attributed to the fact that LaH3 promotes the generation of nano-sized spongy Mg structure, which has good catalytic activity during the subsequent hydrogenation/dehydrogenation process.展开更多
Hydrogen storage is a key link in hydrogen economy,where solid-state hydrogen storage is considered as the most promising approach because it can meet the requirement of high density and safety.Thereinto,magnesium-bas...Hydrogen storage is a key link in hydrogen economy,where solid-state hydrogen storage is considered as the most promising approach because it can meet the requirement of high density and safety.Thereinto,magnesium-based materials(MgH_(2))are currently deemed as an attractive candidate due to the potentially high hydrogen storage density(7.6 wt%),however,the stable thermodynamics and slow kinetics limit the practical application.In this study,we design a ternary transition metal sulfide FeNi_(2)S_(4)with a hollow balloon structure as a catalyst of MgH_(2)to address the above issues by constructing a MgH_(2)/Mg_(2)NiH_(4)-MgS/Fe system.Notably,the dehydrogenation/hydrogenation of MgH_(2)has been significantly improved due to the synergistic catalysis of active species of Mg_(2)Ni/Mg_(2)NiH_(4),MgS and Fe originated from the MgH_(2)-FeNi_(2)S_(4)composite.The hydrogen absorption capacity of the MgH_(2)-FeNi_(2)S_(4)composite reaches to 4.02 wt%at 373 K for 1 h,a sharp contrast to the milled-MgH_(2)(0.67 wt%).In terms of dehydrogenation process,the initial dehydrogenation temperature of the composite is 80 K lower than that of the milled-MgH_(2),and the dehydrogenation activation energy decreases by 95.7 kJ·mol-1 compared with the milled-MgH_(2)(161.2 kJ·mol^(-1)).This method provides a new strategy for improving the dehydrogenation/hydrogenation performance of the MgH_(2)material.展开更多
The introduction of the heterogeneous catalysts with high activity can significantly improve hydrogen storage performance of MgH_(2),therefore,in this paper,we synthesize a carbon-supported transition metal compound,F...The introduction of the heterogeneous catalysts with high activity can significantly improve hydrogen storage performance of MgH_(2),therefore,in this paper,we synthesize a carbon-supported transition metal compound,FeCoS@C derivative from ZIF-67,by utilizing the in situ formed C dispersive multiphase Mg_(2)Co,α-Fe,Co_(3)Fe_(7),and MgS to implement catalysis to MgH_(2).Noteworthily,MgH_(2)-FeCoS@C rapidly ab-sorbs 6.78 wt%H_(2)within 60 s at 573 K and can also absorb 4.56 wt%H_(2)in 900 s at 473 K.Besides,the addition of FeCoS@C results in decreasing of the initial dehydrogenation temperatures of MgH_(2)from 620 to 550 K.The dehydrogenation activation energy of MgH_(2)decreases from 160.7 to 91.9 kJ mol^(-1).Studies show that the Mg_(2)Co,α-Fe,and Co_(3)Fe_(7)act as“hydrogen channels”to accelerate hydrogen transfer due to the presence of transition metals,and MgS with excellent catalytic effect formed from MgH_(2)-FeCoS@C provides a strong and stable catalytic effect.Besides,the carbon skeleton obtained by the carbonization of ZIF-67 not only serves as a dispersion for the multiphase catalytic system,but also provides more active sites for the catalysts.Our study shows that the multiphase and multiscale catalytic system provides an effective strategy for improving the hydrogen storage performance of MgH_(2).展开更多
Nickel metal hydride(Ni-MH)rechargeable batteries hold an important position in the new-energy vehicle market owing to their key technology advantages.Their negative electrode materials—hydrogen storage alloys(HSAs)a...Nickel metal hydride(Ni-MH)rechargeable batteries hold an important position in the new-energy vehicle market owing to their key technology advantages.Their negative electrode materials—hydrogen storage alloys(HSAs)are always on the spotlight and are the key to compete with the burgeoning Li-ion batteries.Here,for the first time we report a series of biphase supperlattice HSAs with a(La,Mg)_(2)Ni_7 matrix phase and a novel(La,Mg)_(7)Ni_(23)secondary phase.The biphase alloys show discharge capacities of402–413 m Ahg^(-1)compared with 376–397 mAhg^(-1)of the other multi-or single-phase alloys.These values are among the highest for superlattice HSAs.In addition,the alloy with 15.4 wt.%(La,Mg)_(7)Ni_(23)phase exhibits good high rate dischargeability due to the proper compromise between the amount of crystal boundaries and equilibrium plateau voltage.The cycling stability of the biphase alloys is lower than that of the single-phase alloy but is till higher than the multiphase alloy.The novel superlattice biphase alloys with superior overall electrochemical properties are expected to inspire further design and development of HSAs as advanced electrode materials for power batteries.展开更多
Poly(amidoamine) dendrimers-modified reduced graphene oxide nanosheets(PAMAM/rGO) composite was selected as a carrier of heterogeneous Ag0.3Co0.7nanoparticles in order to obtain an excellent catalyst for ammonia boran...Poly(amidoamine) dendrimers-modified reduced graphene oxide nanosheets(PAMAM/rGO) composite was selected as a carrier of heterogeneous Ag0.3Co0.7nanoparticles in order to obtain an excellent catalyst for ammonia borane(AB) hydrolysis. During the synthetic processes, GO could easily assembled with PAMAM by the electrostatic and hydrogen-bonding interactions. Structural characterization revealed that Ag0.3Co0.7bimetallic nanoparticles with uniform size distribution of 5 nm are well dispersed on PAMAM/rGO composite architecture. Ag0.3Co0.7@PAMAM/rGO was found to be a highly active and reusable catalyst in hydrogen generation from the hydrolysis of AB with a turnover frequency value(TOF) of 19.79 molH2min-1molM-1at 25.0±0.1℃ and retained 75.4% of their initial activity with a complete release of hydrogen in five runs. The relatively high TOF value and low apparent activation energy(34.21 kJ mol-1) make these Ag0.3Co0.7@PAMAM/rGO NPs as a high-efficient catalyst for catalytic dehydrogenation of AB facilitating the development of practically applicable energy storage materials.展开更多
Electrochemical hydrogen evolution reaction(HER) is a promising route to harvest high-purity hydrogen(H_(2)).Efficient and selective energy transformations rely on the development of novel catalytic materials in terms...Electrochemical hydrogen evolution reaction(HER) is a promising route to harvest high-purity hydrogen(H_(2)).Efficient and selective energy transformations rely on the development of novel catalytic materials in terms of compositions and structures that survive under harsh conditions.This study focuses on a unique nanostructured CoMoS_(3) catalyst for HER under strong acidic and basic electrolyte.The morphologies of the catalysts are fine-tuned by altering reaction times in a hydrothermal reaction.Limited reaction time generates twisted thin-sheet CoMoS_(3)(12 h),which spins into a nanotube with an extended synthetic time(16 h).As the reaction time increases to 20 h,the CoMoS_(3) composite creates open-ended nanotubes,facilitating reactants to penetrate and react actively in the inner space of the nanotubes.Further,prolonged reaction time(24 h) results in the formation of the close-ended CoMoS_(3) nanotubes.We find out that the open-ended structure plays an important role in achieving fast kinetics as well as creating more active sites in HER reaction.The catalyst delivers a profound performance under both acidic and basic conditions,with overpotentials of 93 mV and 115 mV(at a current density of 10 mA/cm^(2)) in the acidic and basic electrolytes,respectively.Moreover,it shows superior long-term durability in both solutions.This work will provide a great foundation for understanding the morphology effect with the same composited catalyst towards energy conversion reactions,not limited to HER.展开更多
La–Mg–Ni-based hydrogen storage alloys have excellent hydrogen storage properties.This work reports the hydrogen storage performance of a series of A_(2)B_(7)-type La_(0.96)Mg_(0.04)N_(i3.34)Al_(0.13)alloy and La_(0...La–Mg–Ni-based hydrogen storage alloys have excellent hydrogen storage properties.This work reports the hydrogen storage performance of a series of A_(2)B_(7)-type La_(0.96)Mg_(0.04)N_(i3.34)Al_(0.13)alloy and La_(0.96-x)Y_(x)Mg_(0.04)Ni_(3.47–0.6x)Al_(0.6x)(x=0,0.22,0.33,0.44)alloys,and explores the effect of Y and Al element combined substitution on the microstructure and hydrogen storage performance of A_(2)B_(7)-type La–Mg–Ni-based alloys.The alloys are composed of Ce_(2)Ni_(7)phase and LaNi_(5)phase.With the increase of x,the cell volume of Ce_(2)Ni_(7)phase decreases,while that of LaNi_(5)phase increases,indicating that Y atom mainly enters Ce_(2)Ni_(7)phase and Al atom mainly enters LaNi_(5)phase.An appropriate amount of co-substitution increases the hydrogen storage capacity and reduces the hydrogen absorption/desorption plateau pressure hysteresis of the alloy.When x=0.44,the hydrogen storage capacity of the alloy is 1.449 wt%,and the hysteresis coefficient is 0.302.The cell volume of Ce_(2)Ni_(7)phase and LaNi_(5)phase expands to different degrees after 20 absorption/desorption cycles.With the increase of x,the volume expansion rate decreases,and the cycle capacity retention rate also gradually decreases.This is related to the amorphization of Ce_(2)Ni_(7)phase.When x=0.22,the capacity retention rate of the alloy is 91.4%.展开更多
Rechargeable aqueous zinc batteries are promising for large-scale energystorage due to their low cost and high safety;however,their energydensity has reached the ceiling based on conventional cathodes with asingle cat...Rechargeable aqueous zinc batteries are promising for large-scale energystorage due to their low cost and high safety;however,their energydensity has reached the ceiling based on conventional cathodes with asingle cationic redox reaction mechanism.Herein,a highly reversiblecathode of typical layered vanadium oxide is reported,which operates onboth the cationic redox couple of v^(5+)/v^(3+)accompanied by the Zn^(2+)storage and the anionic O^(-)/O^(2-)redox couple by anion hosting in anaqueous deep eutectic solvent electrolyte.The reversible oxygen redoxdelivers an additional capacity of-100 mAh g^(-1)at an operating voltage of~1.80 V,which increases the energy density of the cathode by~36%endowing the cathode system a record high energy density of~506 Whkg^(-1).The findings highlight new opportunities for the design of high-energy zinc batteries with both Zn^(2+)and anions as charge carriers.展开更多
Terrestrial evapotranspiration(ET)is a crucial link between Earth’s water cycle and the surface energy budget.Accurate measurement and estimation remain a major challenge in geophysical,biological,and environmental s...Terrestrial evapotranspiration(ET)is a crucial link between Earth’s water cycle and the surface energy budget.Accurate measurement and estimation remain a major challenge in geophysical,biological,and environmental studies.Pioneering work,represented by Dalton and Penman,and the development of theories and experiments on turbulent exchange in the atmospheric boundary layer(ABL),laid the foundation for mainstream methodologies in ET estimation.Since the 1990s,eddy covariance(EC)systems and satellite remote sensing have been widely applied from cold to tropical and from arid to humid regions.They cover water surfaces,wetlands,forests,croplands,grasslands,barelands,and urban areas,offering an exceptional number of reports on diverse ET processes.Surface nocturnal ET,hysteresis between ET and environmental forces,turbulence intermittency,island effects on heterogeneous surfaces,and phase transition between underlying surfaces are examples of reported new phenomena,posing theoretical and practical challenges to mainstream ET methodologies.Additionally,based on non-conventional theories,new methods have emerged,such as maximum entropy production and nonparametric approaches.Furthermore,high-frequency on-site observation and aerospace remote sensing technology in combination form multi-scale observations across plant stomata,leaves,plants,canopies,landscapes,and basins.This promotes an insightful understanding of diverse ET processes and synthesizes the common mechanisms of the processes between and across spatial and temporal scales.All the recent achievements in conception,model,and technology serve as the basis for breaking through the known difficulties in ET estimation.We expect that they will provide a rigorous,reliable scientific basis and experimental support to address theoretical arguments of global significance,such as the water-heat-carbon cycle,and solve practical needs of national importance,including agricultural irrigation and food security,precise management of water resources and eco-environmental protection,and regulation of the urban thermal environment and climate change adaptation.展开更多
Magnesium hydride(MgH_(2))is considered as an ideal hydrogen storage material with excellent hydrogen capacity,but the slow kinetics impedes its application.Herein,an efficient additive of V2C MXene-anchored PrF_(3) n...Magnesium hydride(MgH_(2))is considered as an ideal hydrogen storage material with excellent hydrogen capacity,but the slow kinetics impedes its application.Herein,an efficient additive of V2C MXene-anchored PrF_(3) nanoparticles(PrF_(3)/V_(2)C)was synthesized,which presents excellent catalytic effect in improving the reversibility and stability of hydrogen storage in MgH_(2).The initial dehydrogenation temperature of the 5 wt.% PrF_(3)/V_(2)C-containing MgH_(2)(182℃) is 105℃ lower than that of pure MgH_(2),and 6.5 wt.%hydrogen is rapidly released from 5 wt.%PrF_(3)/V_(2)C-added MgH_(2)sample in 6 min at 240℃.In addition,5 wt.%PrF_(3)/V_(2)C-containing MgH_(2) sample possesses outstanding reversible hydrogen storage capability of 6.5 wt.% after 10 cycles of dehydrogenation and hydrogenation.Microstructure analysis shows that the introduction of Pr improves the stability of V-species(V^(0)and V^(2+))and O-species(lattice oxygen(OL)and vacancy oxygen(OV))formed during ball milling,promotes the interaction between V-species and O-species,and enhances their reversibility,which contributes to the significant improvement in re/dehydrogenation reversibility and cycling stability of MgH_(2).This study provides effective ideas and strategies for the purpose of designing and fabricating high-efficient catalysts for solid-state hydrogen storage materials.展开更多
1 Introduction and main contributions Private entity matching(PEM)[1]is to find records from two or more data sources that refer to the same or similar individuals,without revealing other information besides the match...1 Introduction and main contributions Private entity matching(PEM)[1]is to find records from two or more data sources that refer to the same or similar individuals,without revealing other information besides the matched records.There have been numerous work done for PEM.展开更多
Small convolutional neural network(CNN)-based models usually require transferring knowledge from a large model before they are deployed in computationally resourcelimited edge devices.Masked image modelling(MIM)method...Small convolutional neural network(CNN)-based models usually require transferring knowledge from a large model before they are deployed in computationally resourcelimited edge devices.Masked image modelling(MIM)methods achieve great success in various visual tasks but remain largely unexplored in knowledge distillation for heterogeneous deep models.The reason is mainly due to the significant discrepancy between the transformer-based large model and the CNN-based small network.In this paper,the authors develop the first heterogeneous self-supervised knowledge distillation(HSKD)based on MIM,which can efficiently transfer knowledge from large transformer models to small CNN-based models in a self-supervised fashion.Our method builds a bridge between transformer-based models and CNNs by training a UNet-style student with sparse convolution,which can effectively mimic the visual representation inferred by a teacher over masked modelling.Our method is a simple yet effective learning paradigm to learn the visual representation and distribution of data from heterogeneous teacher models,which can be pre-trained using advanced self-supervised methods.Extensive experiments show that it adapts well to various models and sizes,consistently achieving state-of-the-art performance in image classification,object detection,and semantic segmentation tasks.For example,in the Imagenet 1K dataset,HSKD improves the accuracy of Resnet-50(sparse)from 76.98%to 80.01%.展开更多
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the financial support by the National Nat-ural Science Foundation of China(Nos.52201282,52071281,52371239)the China Postdoctoral Science Foundation(No.2023M742945)+4 种基金Hebei Provincial Postdoctoral Science Foundation(No.B2023003023)the Science Research Project of Hebei Education Department(No.BJK2022033)the Natural Science Foundation of Hebei Province(No.C2022203003)the Inner Mongolia Science and Technology Major Project(No.2020ZD0012)the Baotou Science and Technology Planning Project(No.XM2022BT09).
文摘La-Mg-Ni-based hydrogen storage alloys with superlattice structures are the new generation anode material for nickel metal hydride(Ni-MH)batteries owing to the advantages of high capacity and exceptional activation properties.However,the cycling stability is not currently satisfactory enough which plagues its application.Herein,a strategy of partially substituting La with the Y element is proposed to boost the capacity durability of La-Mg-Ni-based alloys.Furthermore,phase structure regulation is implemented simultaneously to obtain the A5 B19-type alloy with good crystal stability specifically.It is found that Y promotes the phase formation of the Pr5 Co19-type phase after annealing at 985℃.The alloy containing Y contributes to the superior rate capability resulting from the promoted hydrogen diffusion rate.Notably,Y substitution enables strengthening the anti-pulverization ability of the alloy in terms of increasing the volume match between[A_(2)B_(4)]and[AB5]subunits,and effectively enhances the anti-corrosion ability of the alloy due to high electronegativity,realizing improved long-term cycling stability of the alloy from 74.2%to 78.5%after cycling 300 times.The work is expected to shed light on the composition and structure design of the La-Mg-Ni-based hydrogen storage alloy for Ni-MH batteries.
基金financially supported by the Natural Science Foundation of Hebei Province(Nos.E2019203414,E2020203081 and E2019203161)the National Natural Science Foundation of China(Nos.51701175 and 51971197)+1 种基金the Innovation Fund for the Graduate Students of Hebei Province(No.CXZZBS2020062)the Doctoral Fund of Yanshan University(No.BL19031)
文摘Rare earth-Mg-Ni-based alloys with superlattice structures are new generation negative electrode materials for the nickel metal hydride batteries.Among them,the novel AB_(4)-type superlattice structure alloy is supposed to have superior cycling stability and rate capability.Yet its preparation is hindered by the crucial requirement of temperature and the special composition which is close to the other superlattice structure.Here,we prepare rare earth-Mg-Ni-based alloy and study the phase transformation of alloys to make clear the formation of AB_(4)-type phase.It is found Pr_(5)Co_(19)-type phase is converted from Ce_(5)Co_(19)-type phase and shows good stability at higher temperature compared to the Ce_(5)Co_(19)-type phase in the range of 930-970℃.Afterwards,with further 5℃increasing,AB_(4)-type superlattice structure forms at a temperature of 975℃by consuming Pr_(5)Co_(19)-type phase.In contrast with A_(5)B_(19)-type alloy,AB_(4)-type alloy has superior rate capability owing to the dominant advantages of charge transfer and hydrogen diffusion.Besides,AB_(4)-type alloy shows long lifespan whose capacity retention rates are 89.2%at the 100;cycle and 82.8%at the 200;cycle,respectively.AB_(4)-type alloy delivers 1.53 wt.%hydrogen storage capacity at room temperature and exhibits higher plateau pressure than Pr_(5)Co_(19)-type alloy.The work provides novel AB_(4)-type alloy with preferable electrochemical performance as negative electrode material to inspire the development of nickel metal hydride batteries.
基金supported by the National Natural Science Foundation of China(51771164,51571173)China Postdoctoral Science Foundation(2016M601281)Scientific Research Projects in Colleges and Universities in Hebei Province,China(ZD2014004,QN2016002)
文摘In this work,a Mg-based composite material with in-situ formed LaH3, Mg2 NiH4-LiBH4 ＋ 20 wt% LaH3,was prepared by ball milling LiBH4 and hydrogenated LaMg2 Ni and Mg2 Ni powder mixture, followed by heat treatment at 573 K. The onset dehydrogenation temperature of the composite is reduced by 50 K compared with that of Mg2 NiH4-LiBH4. The LaH3-doped composite shows faster kinetics,absorbing1.43 wt% hydrogen within 100 s at 423 K,which is 6.5 times faster than Mg2 NiH4-LiBH4. Moreover,the composite releases 1.24 wt% hydrogen within 500 s at 573 K,0.69 wt% higher than Mg2 NiH4-LiBH4. The activation energy of the composite is reduced by 8.2 and 80 kJ/mol compared with that of Mg2 NiH4-LiBH4 and commercial MgH2, respectively. The improvement in hydrogen storage properties is attributed to the fact that LaH3 promotes the generation of nano-sized spongy Mg structure, which has good catalytic activity during the subsequent hydrogenation/dehydrogenation process.
基金This work was supported by the National Natural Science Foundation of China(grant numbers 52071281 and 51971197)the Natural Science Foundation of Hebei Province(grant numbers E2019203161,E2019203414 and E2020203081)Science and Technology Major project of Inner Mongolia(2020ZD0012).
文摘Hydrogen storage is a key link in hydrogen economy,where solid-state hydrogen storage is considered as the most promising approach because it can meet the requirement of high density and safety.Thereinto,magnesium-based materials(MgH_(2))are currently deemed as an attractive candidate due to the potentially high hydrogen storage density(7.6 wt%),however,the stable thermodynamics and slow kinetics limit the practical application.In this study,we design a ternary transition metal sulfide FeNi_(2)S_(4)with a hollow balloon structure as a catalyst of MgH_(2)to address the above issues by constructing a MgH_(2)/Mg_(2)NiH_(4)-MgS/Fe system.Notably,the dehydrogenation/hydrogenation of MgH_(2)has been significantly improved due to the synergistic catalysis of active species of Mg_(2)Ni/Mg_(2)NiH_(4),MgS and Fe originated from the MgH_(2)-FeNi_(2)S_(4)composite.The hydrogen absorption capacity of the MgH_(2)-FeNi_(2)S_(4)composite reaches to 4.02 wt%at 373 K for 1 h,a sharp contrast to the milled-MgH_(2)(0.67 wt%).In terms of dehydrogenation process,the initial dehydrogenation temperature of the composite is 80 K lower than that of the milled-MgH_(2),and the dehydrogenation activation energy decreases by 95.7 kJ·mol-1 compared with the milled-MgH_(2)(161.2 kJ·mol^(-1)).This method provides a new strategy for improving the dehydrogenation/hydrogenation performance of the MgH_(2)material.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.52071281 and 51971197)the Natural Science Foundation of Hebei Province(Nos.C2022203003 and E2020203081)+1 种基金the Science and Technology Project of Hebei Education Department(No.BJK2022033)the Hebei Province Foundation for Returned Talent(No.C20210322).
文摘The introduction of the heterogeneous catalysts with high activity can significantly improve hydrogen storage performance of MgH_(2),therefore,in this paper,we synthesize a carbon-supported transition metal compound,FeCoS@C derivative from ZIF-67,by utilizing the in situ formed C dispersive multiphase Mg_(2)Co,α-Fe,Co_(3)Fe_(7),and MgS to implement catalysis to MgH_(2).Noteworthily,MgH_(2)-FeCoS@C rapidly ab-sorbs 6.78 wt%H_(2)within 60 s at 573 K and can also absorb 4.56 wt%H_(2)in 900 s at 473 K.Besides,the addition of FeCoS@C results in decreasing of the initial dehydrogenation temperatures of MgH_(2)from 620 to 550 K.The dehydrogenation activation energy of MgH_(2)decreases from 160.7 to 91.9 kJ mol^(-1).Studies show that the Mg_(2)Co,α-Fe,and Co_(3)Fe_(7)act as“hydrogen channels”to accelerate hydrogen transfer due to the presence of transition metals,and MgS with excellent catalytic effect formed from MgH_(2)-FeCoS@C provides a strong and stable catalytic effect.Besides,the carbon skeleton obtained by the carbonization of ZIF-67 not only serves as a dispersion for the multiphase catalytic system,but also provides more active sites for the catalysts.Our study shows that the multiphase and multiscale catalytic system provides an effective strategy for improving the hydrogen storage performance of MgH_(2).
基金financially supported by the National Natural Science Foundation of China(Nos.51801176 and 51701226)the Natural Science Foundation of Hebei Province(Nos.E2019203414 and E2020203081)the High-end Talent Support Program of Yangzhou University and the Qinglan Engineering Project of Yangzhou University。
文摘Nickel metal hydride(Ni-MH)rechargeable batteries hold an important position in the new-energy vehicle market owing to their key technology advantages.Their negative electrode materials—hydrogen storage alloys(HSAs)are always on the spotlight and are the key to compete with the burgeoning Li-ion batteries.Here,for the first time we report a series of biphase supperlattice HSAs with a(La,Mg)_(2)Ni_7 matrix phase and a novel(La,Mg)_(7)Ni_(23)secondary phase.The biphase alloys show discharge capacities of402–413 m Ahg^(-1)compared with 376–397 mAhg^(-1)of the other multi-or single-phase alloys.These values are among the highest for superlattice HSAs.In addition,the alloy with 15.4 wt.%(La,Mg)_(7)Ni_(23)phase exhibits good high rate dischargeability due to the proper compromise between the amount of crystal boundaries and equilibrium plateau voltage.The cycling stability of the biphase alloys is lower than that of the single-phase alloy but is till higher than the multiphase alloy.The novel superlattice biphase alloys with superior overall electrochemical properties are expected to inspire further design and development of HSAs as advanced electrode materials for power batteries.
基金financially supported by the National Natural Science Foundation of China(Nos.21303157 and 51571173)the Scientific Research Projects in Colleges and Universities in Hebei Province(No.QN2016002)the Innovation Fund for the Graduate Students of Hebei Province(No.2016SJBS018)
文摘Poly(amidoamine) dendrimers-modified reduced graphene oxide nanosheets(PAMAM/rGO) composite was selected as a carrier of heterogeneous Ag0.3Co0.7nanoparticles in order to obtain an excellent catalyst for ammonia borane(AB) hydrolysis. During the synthetic processes, GO could easily assembled with PAMAM by the electrostatic and hydrogen-bonding interactions. Structural characterization revealed that Ag0.3Co0.7bimetallic nanoparticles with uniform size distribution of 5 nm are well dispersed on PAMAM/rGO composite architecture. Ag0.3Co0.7@PAMAM/rGO was found to be a highly active and reusable catalyst in hydrogen generation from the hydrolysis of AB with a turnover frequency value(TOF) of 19.79 molH2min-1molM-1at 25.0±0.1℃ and retained 75.4% of their initial activity with a complete release of hydrogen in five runs. The relatively high TOF value and low apparent activation energy(34.21 kJ mol-1) make these Ag0.3Co0.7@PAMAM/rGO NPs as a high-efficient catalyst for catalytic dehydrogenation of AB facilitating the development of practically applicable energy storage materials.
基金the financial support from the National Natural Science Foundation of China(Nos.51971197 and 51771164)the National Science Foundation of Hebei Province(E2019203161 and E2018203117)。
文摘Electrochemical hydrogen evolution reaction(HER) is a promising route to harvest high-purity hydrogen(H_(2)).Efficient and selective energy transformations rely on the development of novel catalytic materials in terms of compositions and structures that survive under harsh conditions.This study focuses on a unique nanostructured CoMoS_(3) catalyst for HER under strong acidic and basic electrolyte.The morphologies of the catalysts are fine-tuned by altering reaction times in a hydrothermal reaction.Limited reaction time generates twisted thin-sheet CoMoS_(3)(12 h),which spins into a nanotube with an extended synthetic time(16 h).As the reaction time increases to 20 h,the CoMoS_(3) composite creates open-ended nanotubes,facilitating reactants to penetrate and react actively in the inner space of the nanotubes.Further,prolonged reaction time(24 h) results in the formation of the close-ended CoMoS_(3) nanotubes.We find out that the open-ended structure plays an important role in achieving fast kinetics as well as creating more active sites in HER reaction.The catalyst delivers a profound performance under both acidic and basic conditions,with overpotentials of 93 mV and 115 mV(at a current density of 10 mA/cm^(2)) in the acidic and basic electrolytes,respectively.Moreover,it shows superior long-term durability in both solutions.This work will provide a great foundation for understanding the morphology effect with the same composited catalyst towards energy conversion reactions,not limited to HER.
基金supported by the National Key Research and Development Program of China(No.2022YFB3803800)the National Natural Science Foundation of China(Nos.51971197 and 52071281)+4 种基金the Basic Innovation Research Project in Yanshan University(No.2022LGZD004)the China Postdoctoral Science Foundation(No.2023M742945)the Postdoctoral Research Project of Hebei Province(No.B2023003023)the Subsidy for Hebei Key Laboratory of Applied Chemistry after Operation Performance(No.22567616H)the Special Project for Local Science and Technology Development Guided by the Central Government of China(No.236Z1406G).
文摘La–Mg–Ni-based hydrogen storage alloys have excellent hydrogen storage properties.This work reports the hydrogen storage performance of a series of A_(2)B_(7)-type La_(0.96)Mg_(0.04)N_(i3.34)Al_(0.13)alloy and La_(0.96-x)Y_(x)Mg_(0.04)Ni_(3.47–0.6x)Al_(0.6x)(x=0,0.22,0.33,0.44)alloys,and explores the effect of Y and Al element combined substitution on the microstructure and hydrogen storage performance of A_(2)B_(7)-type La–Mg–Ni-based alloys.The alloys are composed of Ce_(2)Ni_(7)phase and LaNi_(5)phase.With the increase of x,the cell volume of Ce_(2)Ni_(7)phase decreases,while that of LaNi_(5)phase increases,indicating that Y atom mainly enters Ce_(2)Ni_(7)phase and Al atom mainly enters LaNi_(5)phase.An appropriate amount of co-substitution increases the hydrogen storage capacity and reduces the hydrogen absorption/desorption plateau pressure hysteresis of the alloy.When x=0.44,the hydrogen storage capacity of the alloy is 1.449 wt%,and the hysteresis coefficient is 0.302.The cell volume of Ce_(2)Ni_(7)phase and LaNi_(5)phase expands to different degrees after 20 absorption/desorption cycles.With the increase of x,the volume expansion rate decreases,and the cycle capacity retention rate also gradually decreases.This is related to the amorphization of Ce_(2)Ni_(7)phase.When x=0.22,the capacity retention rate of the alloy is 91.4%.
基金Science Research Project of Hebei Education Department,Grant/Award Number:BJK2022033Hebei Province Foundation for Returned Talent,Grant/Award Number:C20210322+4 种基金National Natural Science Foundation of China,Grant/Award Numbers:52371239,52201282Natural Science Foundation of Hebei Province,Grant/Award Number:C2022203003China Postdoctoral Science Foundation,Grant/Award Number:2023M742945Hebei Provincial Postdoctoral Science Foundation,Grant/Award Number:B2023003023Subsidy for Hebei Key Laboratory of Applied Chemistry after Operation Performance,Grant/Award Number:22567616H
文摘Rechargeable aqueous zinc batteries are promising for large-scale energystorage due to their low cost and high safety;however,their energydensity has reached the ceiling based on conventional cathodes with asingle cationic redox reaction mechanism.Herein,a highly reversiblecathode of typical layered vanadium oxide is reported,which operates onboth the cationic redox couple of v^(5+)/v^(3+)accompanied by the Zn^(2+)storage and the anionic O^(-)/O^(2-)redox couple by anion hosting in anaqueous deep eutectic solvent electrolyte.The reversible oxygen redoxdelivers an additional capacity of-100 mAh g^(-1)at an operating voltage of~1.80 V,which increases the energy density of the cathode by~36%endowing the cathode system a record high energy density of~506 Whkg^(-1).The findings highlight new opportunities for the design of high-energy zinc batteries with both Zn^(2+)and anions as charge carriers.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.51879255,41430855).
文摘Terrestrial evapotranspiration(ET)is a crucial link between Earth’s water cycle and the surface energy budget.Accurate measurement and estimation remain a major challenge in geophysical,biological,and environmental studies.Pioneering work,represented by Dalton and Penman,and the development of theories and experiments on turbulent exchange in the atmospheric boundary layer(ABL),laid the foundation for mainstream methodologies in ET estimation.Since the 1990s,eddy covariance(EC)systems and satellite remote sensing have been widely applied from cold to tropical and from arid to humid regions.They cover water surfaces,wetlands,forests,croplands,grasslands,barelands,and urban areas,offering an exceptional number of reports on diverse ET processes.Surface nocturnal ET,hysteresis between ET and environmental forces,turbulence intermittency,island effects on heterogeneous surfaces,and phase transition between underlying surfaces are examples of reported new phenomena,posing theoretical and practical challenges to mainstream ET methodologies.Additionally,based on non-conventional theories,new methods have emerged,such as maximum entropy production and nonparametric approaches.Furthermore,high-frequency on-site observation and aerospace remote sensing technology in combination form multi-scale observations across plant stomata,leaves,plants,canopies,landscapes,and basins.This promotes an insightful understanding of diverse ET processes and synthesizes the common mechanisms of the processes between and across spatial and temporal scales.All the recent achievements in conception,model,and technology serve as the basis for breaking through the known difficulties in ET estimation.We expect that they will provide a rigorous,reliable scientific basis and experimental support to address theoretical arguments of global significance,such as the water-heat-carbon cycle,and solve practical needs of national importance,including agricultural irrigation and food security,precise management of water resources and eco-environmental protection,and regulation of the urban thermal environment and climate change adaptation.
基金supported by the National Natural Science Foundation of China(Nos.U22A20120,52071135,51871090,and U1804135)the Natural Science Foundation of Hebei Province for Innovation Groups Program(No.C2022203003)Fundamental Research Funds for the Universities of Henan Province(No.NSFRF220201).
文摘Magnesium hydride(MgH_(2))is considered as an ideal hydrogen storage material with excellent hydrogen capacity,but the slow kinetics impedes its application.Herein,an efficient additive of V2C MXene-anchored PrF_(3) nanoparticles(PrF_(3)/V_(2)C)was synthesized,which presents excellent catalytic effect in improving the reversibility and stability of hydrogen storage in MgH_(2).The initial dehydrogenation temperature of the 5 wt.% PrF_(3)/V_(2)C-containing MgH_(2)(182℃) is 105℃ lower than that of pure MgH_(2),and 6.5 wt.%hydrogen is rapidly released from 5 wt.%PrF_(3)/V_(2)C-added MgH_(2)sample in 6 min at 240℃.In addition,5 wt.%PrF_(3)/V_(2)C-containing MgH_(2) sample possesses outstanding reversible hydrogen storage capability of 6.5 wt.% after 10 cycles of dehydrogenation and hydrogenation.Microstructure analysis shows that the introduction of Pr improves the stability of V-species(V^(0)and V^(2+))and O-species(lattice oxygen(OL)and vacancy oxygen(OV))formed during ball milling,promotes the interaction between V-species and O-species,and enhances their reversibility,which contributes to the significant improvement in re/dehydrogenation reversibility and cycling stability of MgH_(2).This study provides effective ideas and strategies for the purpose of designing and fabricating high-efficient catalysts for solid-state hydrogen storage materials.
基金This work was supported by the National Basic Research 973 Program of China(2012CB316201)the National Natural Science Foundation of China(Grant Nos.61472070,61672142,61602103,2018YFB1003404).
文摘1 Introduction and main contributions Private entity matching(PEM)[1]is to find records from two or more data sources that refer to the same or similar individuals,without revealing other information besides the matched records.There have been numerous work done for PEM.
文摘Small convolutional neural network(CNN)-based models usually require transferring knowledge from a large model before they are deployed in computationally resourcelimited edge devices.Masked image modelling(MIM)methods achieve great success in various visual tasks but remain largely unexplored in knowledge distillation for heterogeneous deep models.The reason is mainly due to the significant discrepancy between the transformer-based large model and the CNN-based small network.In this paper,the authors develop the first heterogeneous self-supervised knowledge distillation(HSKD)based on MIM,which can efficiently transfer knowledge from large transformer models to small CNN-based models in a self-supervised fashion.Our method builds a bridge between transformer-based models and CNNs by training a UNet-style student with sparse convolution,which can effectively mimic the visual representation inferred by a teacher over masked modelling.Our method is a simple yet effective learning paradigm to learn the visual representation and distribution of data from heterogeneous teacher models,which can be pre-trained using advanced self-supervised methods.Extensive experiments show that it adapts well to various models and sizes,consistently achieving state-of-the-art performance in image classification,object detection,and semantic segmentation tasks.For example,in the Imagenet 1K dataset,HSKD improves the accuracy of Resnet-50(sparse)from 76.98%to 80.01%.
