We demonstrate a case study of Ce-doped yttrium aluminum garnet(YAG)phosphor to illustrate a novel plasma route for the synthesis of multicomponent materials with addressing morphology and structural control.The prese...We demonstrate a case study of Ce-doped yttrium aluminum garnet(YAG)phosphor to illustrate a novel plasma route for the synthesis of multicomponent materials with addressing morphology and structural control.The presented strategy was started directly from liquid precursors without any precipitating agents,and an innovative growth mechanism was proposed to explain the formation of monodispersed spherical particles with an adjusted size distribution.Homogeneous elemental distribution close to that of liquid precursors was also achieved due to the thermal nonequilibrium effect in plasma.Benefiting from the structural feature of the obtained product,a low transformation temperature of 1100℃for YAG phase was obtained and final products exhibit the highest photoluminescence intensity with rather low Ce doping of 0.5 wt.%,together with excellent thermal stability of 92%preservation of initial emission at 473 K.This work well illustrates the advance of plasma strategy in formation of multicomponent com-pounds with excellent performances,and its potential for large-scale production due to the transient and in-flight synthesis process.展开更多
A novel trace nickel(Ni)doped tungsten(W)matrix with coated Ni on W grains was prepared by powder metallurgy method.The introduction of Ni can inhibit the reaction between W and barium-calcium aluminates(Ba-Ca alumina...A novel trace nickel(Ni)doped tungsten(W)matrix with coated Ni on W grains was prepared by powder metallurgy method.The introduction of Ni can inhibit the reaction between W and barium-calcium aluminates(Ba-Ca aluminates)during the impregnation process of the matrix.After cathode activation,the surface Ba:O molar ratio is 0.88:1.00,much higher than the Ba dispenser cathode without Ni doping.The XPS results of the cathode surface showed that the metallic Ba appeared on the activated cathode surface,forming dipoles with oxygen,and effectively reducing the cathode surface work function.The pulse electron emission current density at 1100℃_(b)(brightness temperature)was 18.26 A/cm^(2),and the calculated work function was 1.97 eV.It has a low evaporation rate and the accelerated lifetime test predict a lifetime of over 160000 h.First-principles calculations showed that the charge transfer and dipole moment in the NiW-BaO system were both increased compared to the Ba dispenser cathode,thus improving the emission performance of the Ni-W mixed matrix cathode.展开更多
The densification characterization,phase constitution,precipitation evolution and mechanical performance of Al−Mg−Sc−Zr alloy processed by laser powder bed fusion(LPBF)were systematically investigated.Moreover,the evo...The densification characterization,phase constitution,precipitation evolution and mechanical performance of Al−Mg−Sc−Zr alloy processed by laser powder bed fusion(LPBF)were systematically investigated.Moreover,the evolution of phase constitution and precipitation behavior after heat treatment were characterized by using X-ray diffraction(XRD)and transmission electron microscope(TEM)analysis.The ultimate tensile strength(UTS)of as-built samples ranged from 396.8 to 414.6 MPa as the scanning speed decreased from 1600 to 1000 mm/s.After post heat treatment,the yield strength(YS)increased to(513.1±1.3)MPa,while the UTS increased from(414.6±5.1)to(539.2±1.5)MPa.The significant improvement of mechanical performance was ascribed to the formation of secondary Al3(Sc,Zr)precipitates.展开更多
Porous carbon microspheres are widely regarded as a superior CO_(2) adsorbent due to their exceptional efficiency and affordability.However,better adsorption performance is very attractive for porous carbon microspher...Porous carbon microspheres are widely regarded as a superior CO_(2) adsorbent due to their exceptional efficiency and affordability.However,better adsorption performance is very attractive for porous carbon microspheres.And modification of the pore structure is one of the effective strategies.In this study,multi-cavity mesoporous carbon microspheres were successfully synthesized by the synergistic method of soft and hard templates,during which a phenolic resin with superior thermal stability was employed as the carbon precursor and a mixture of silica sol and F108 as the mesoporous template.Carbon microspheres with multi-cavity mesoporous structures were prepared,and all the samples showed highly even mesopores,with diameters around 12 nm.The diameter of these microspheres decreased from 396.8 nm to about 182.5 nm with the increase of silica sol.After CO_(2) activation,these novel carbon microspheres(APCF0.5-S1.75)demonstrated high specific surface area(983.3 m^(2)/g)and remarkable CO_(2) uptake of 4.93 mmol/g at 0℃ and1 bar.This could be attributed to the unique multi-cavity structure,which offers uniform mesoporous pore channels,minimal CO_(2) transport of and a greater number of active sites for CO_(2) adsorption.展开更多
The chemical reaction between lanthanum oxide and molybdenum carbide was studied by thermodynamic calculation, thermal analysis and in situ X ray Photoelectron Spectroscopy. The theoretical results show that at the ...The chemical reaction between lanthanum oxide and molybdenum carbide was studied by thermodynamic calculation, thermal analysis and in situ X ray Photoelectron Spectroscopy. The theoretical results show that at the environment allowing for the evaporation of lanthanum, such as in high vacuum, La 2O 3 in the La 2O 3 Mo materials can be reduced to metallic lanthanum by molybdenum carbide (Mo 2C). To confirm the conclusion, many analysis methods such as XRD, SPS, and TG DTA were taken. The experimental results show that the chemical state of lanthanum changes during heating. It was proved, for the first time, that reacted metallic lanthanum appears at the surface of this kind of material at high temperature.展开更多
Water pollution regarding dyes and heavy metal ions is crucial facing the world.How to effectively separate these contaminants from water has been a key issue.Graphene oxide(GO)promises the greenwater world as a long-...Water pollution regarding dyes and heavy metal ions is crucial facing the world.How to effectively separate these contaminants from water has been a key issue.Graphene oxide(GO)promises the greenwater world as a long-lasting spotlight adsorbent material and therefore,harnessing GO has been the research hotspot for over a decade.The state of GO as well as its surface functional groups plays an important role in adsorption.And the way of preparation and structural modification matters to the performance of GO.In this review,the significance of the state of existence of stock GO and surface functional groups is explored in terms of preparation,structural modification,and adsorption.Besides,various adsorbates for GO adsorption are also involved,the discussion of which is rarely established elsewhere.展开更多
We report on the preparation of a well-defined star-shaped tricationic ionic liquid possessing three arms of poly（ethylene glycol） functionalized imidazolium rings. Remarkable solubility was found in most of the org...We report on the preparation of a well-defined star-shaped tricationic ionic liquid possessing three arms of poly（ethylene glycol） functionalized imidazolium rings. Remarkable solubility was found in most of the organic solvents we used. Thermogravimetric analysis（TGA） exhibited excellent thermal stability and two distinct decomposition temperatures were attributed to two kinds of chemical degradation. Differential scanning calorimetry（DSC） was further employed to investigate the thermal phase transitions, that three different signals（Tg, Tc, and Tm） were shown upon the second heating process. Moreover, CH2Cl2 solution of the ionic liquid expressed an excitation-wavelength dependent fluorescence response, leading to the facile modulation of photoluminescence behavior. This work represents an example of utilizing molecular design to construct novel ionic liquids and endow further potential to be used in the engineering materials.展开更多
The design and synthesis of non-precious metal dual-functional electrocatalysts through the modulation of electronic structure are important for the development of renewable hydrogen energy.Herein,MnS_(2)/MnO_(2)-CC h...The design and synthesis of non-precious metal dual-functional electrocatalysts through the modulation of electronic structure are important for the development of renewable hydrogen energy.Herein,MnS_(2)/MnO_(2)-CC heterostructure dual-functional catalysts with ultrathin nanosheets were prepared by a twostep electrodeposition method for efficient acidic hydrogen evolution reaction(HER) and degradation of organic wastewater(such as methylene blue(MB)).The electronic structure of Mn atoms at the MnS_(2)/MnO_(2)-CC heterostructure interface is reconfigured under the joint action of S and O atoms.Theoretical calculations show that the Mn d-band electron distribution in MnS_(2)/MnO_(2)-CC catalyst has higher occupied states near the Fermi level compared to the MnO_(2) and MnS_(2) catalysts,which indicates that MnS_(2)/MnO_(2)-CC catalyst has better electron transfer capability and catalytic activity.The MnS_(2)/MnO_(2)-CC catalysts require overpotential of only 66 and 116 mV to reach current density of 10 and 100 mA cm^(-2)in MB/H_(2)SO_(4) media.The MnS_(2)/MnO_(2)-CC catalyst also has a low Tafel slope(26.72 mV dec^(-1)) and excellent stability(the performance does not decay after 20 h of testing).In addition,the MB removal efficiency of the MnS_(2)/MnO_(2)-CC catalyst with a better kinetic rate(0.0226) can reach 97.76%,which is much higher than that of the MnO_(x)-CC catalyst(72.10%).This strategy provides a new way to develop efficient and stable non-precious metal dual-functional electrocatalysts for HER and organic wastewater degradation.展开更多
Due to the greenhouse effect caused by carbon dioxide(CO_(2))emission,much attention has been paid for the removal of CO_(2).Porous liquids(PLs),as new type of liquid materials,have obvious advantages in mass and heat...Due to the greenhouse effect caused by carbon dioxide(CO_(2))emission,much attention has been paid for the removal of CO_(2).Porous liquids(PLs),as new type of liquid materials,have obvious advantages in mass and heat transfer,which are widely used in gas adsorption and sep-aration.Metal–organic frameworks(MOFs)with merits like large surface area,inherent porous structure and adjustable topology have been considered as one of the best candidates for PLs construction.This review presents the state-of-the-art status on the fabrication strategy of MOFs-based PLs and their CO_(2) absorption and utilization performance,and the positive effects of porosity and functional modification on the absorption-desorption property,selectivity of target product,and regeneration ability are well summarized.Finally,the challenges and prospects for MOFs-based PLs in the optimization of preparation,the coupling of multiple removal techniques,the in situ characterization methods,the regeneration and cycle stability,the environmental impact as well as expansion of application are proposed.展开更多
In this work,silicon-carbon hybrid materials were adopted as an example to illustrate the novel strategy to in situ construct heterostructure with adjustable microstructure.Based on the temperature-dependent thermodyn...In this work,silicon-carbon hybrid materials were adopted as an example to illustrate the novel strategy to in situ construct heterostructure with adjustable microstructure.Based on the temperature-dependent thermodynamics and kinetics of reaction between Si and C,the processes for Si nanocrystals growth and C decoration were coupled at different zones of plasma flame according to its temperature and velocity fields by theoretical modeling,aiming to intentionally suppress the formation of undesirable carbide,and enable adjusting the microstructure of each counterpart separately in transient process.As a result,well-controlled Si/C nanocomposites,including nanospheres and nanowires with core-shell structures,were achieved,and this continuous and in-flight route is also potential for large-scale production.Further investigation on the electrochemical properties highlights the advantage of as proposed strategy to efficiently construct heterostructures with superior performance for various applications.展开更多
The microstructure of(Nd,Ce)-Fe-B sintered magnets with different diffusion depths was characterized by a magnetic force microscope,and the relationship between the magnetic properties and the local structure of grain...The microstructure of(Nd,Ce)-Fe-B sintered magnets with different diffusion depths was characterized by a magnetic force microscope,and the relationship between the magnetic properties and the local structure of grain boundary diffused magnets is discussed.The domains perpendicular to the c-axis(easy magnetization direction)show a typical maze-like pattern,while those parallel to the c-axis show the characte ristics of plate domains.The significant gradient change is shown in the concentration of Dy with the direction of diffusion from the surface to the interior.Dy diffuses along grain boundaries and(Dy,Nd)_(2)Fe_(14)B layer with a high anisotropy field formed around the grains.Through in-situ electron probe micro-analysis/magnetic force microscopy(EPMA/MFM),it is found that the average domain width decreases,and the proportion of single domain grains increases as diffusion depth increases.This is caused by both the change of concentration and distribution of Dy.The grain boundary diffusion process changes the microstructure and microchemistry inside the magnet,and these local magnetism differences can be reflected by the configuration of the magnetic domain structure.展开更多
The sodium-iodine(Na-I)battery exhibits significant potential as an alternative energy storage device to the lithium-ion battery.However,its development is hindered by inadequate electrical and thermal stability,as we...The sodium-iodine(Na-I)battery exhibits significant potential as an alternative energy storage device to the lithium-ion battery.However,its development is hindered by inadequate electrical and thermal stability,as well as the dissolution and shuttling of polyiodide.In this study,we report a preparation method for melamine carbon sponge(MC)via carbonizing a commercially available kitchen sponge.It was revealed that the as-prepared MC,composed of unique self-growing carbon nanotubes,could provide both physical and chemical adsorption capabilities for intermediate polyiodides to improve the electrochemical performance of NaI.Consequently,the NaI/MC electrode effectively minimized polyiodide dissolution and reduced the electrochemical impedance.The NaI/MC cathode demonstrated a high average discharge capacity of 92.75 mAh·g^(–1)over 200 cycles while maintaining a coulombic efficiency of 94%.The research findings from our study have promising applications in Na-I batteries.展开更多
Immiscible bimetal systems,of which tungsten–copper(W–Cu)is a typical representative,have crucial applications in fields requiring both mechanical and physical properties.Nevertheless,it is a major challenge to dete...Immiscible bimetal systems,of which tungsten–copper(W–Cu)is a typical representative,have crucial applications in fields requiring both mechanical and physical properties.Nevertheless,it is a major challenge to determine how to give full play to the advantages of the two phases of the bimetal and achieve outstanding comprehensive properties.In this study,an ultrafine-grained W–Cu bimetal with spatially connected Cu and specific Wislands was fabricated through a designed powder-mixing process and subsequent rapid low-temperature sintering.The prepared bimetal concurrently has a high yield strength,large plastic strain,and high electrical conductivity.The stress distribution and strain response of individual phases in different types of W–Cu bimetals under loading were quantified by means of a simulation.The high yield strength of the reported bimetal results from the microstructure refinement and high contiguity of the grains in the W islands,which enhance the contribution of W to the total plastic deformation of the bimetal.The high electrical conductivity is attributed to the increased mean free path of the Cu and the reduced proportion of phase boundaries due to the specific phase combination of W islands and Cu.This work provides new insight into modulating phase configuration in immiscible metallic composites to achieve high-level multi-objective properties.展开更多
A heterogeneous structure composed of elongated primaryαand secondaryαgrains with a size of 670 nm was produced by subjecting the bimodal microstructure of a titanium alloy to hot rolling,annealing,and aging treatme...A heterogeneous structure composed of elongated primaryαand secondaryαgrains with a size of 670 nm was produced by subjecting the bimodal microstructure of a titanium alloy to hot rolling,annealing,and aging treatments.This heterogeneous structure exhibited significantly improved strength owing to a combination of heterogeneous deformation-induced strengthening and dislocation strengthening.A short-duration high-temperature heat treatment facilitated a synergistic enhancement of yield strength and elongation at both room temperature and 650℃.The fracture elongation at room temperature and 650℃ increased by 36.7% and 130.4%,respectively,compared with that of bimodal microstructure.The stacking of geometrically necessary dislocations with a single slip system at the phase boundary and the longer effective slip length of the dislocations are the reasons for the significant improvement in elongation.The elongated primary α phase in lamellar bimodal microstructure,composed of multiple primary α grains,has better resistance to the anti-fatigue crack initiation effect.展开更多
Hazardous wastes from the production of cleaner fuels,spent hydrodesulfurization(HDS)catalysts,pose a threat to the environment and the sustainability of rare metal resources.However,conventional recovery approaches a...Hazardous wastes from the production of cleaner fuels,spent hydrodesulfurization(HDS)catalysts,pose a threat to the environment and the sustainability of rare metal resources.However,conventional recovery approaches are limited by long processes,easy generation of waste liquids,and difficult reuse of recovery products.Herein,a SiO_(2)-Na_(2)O-B_(2)O_(3)-MgO-TiO_(2)glass phase extraction system was proposed for the full-component recycle from spent MoNi/γ-Al_(2)O_(3)catalysts to the materials,including the individual recovery of Mo and the synthesis of Ni^(2+)-doped glass–ceramics.96.7%of Ni and 99.8%of Al were extracted into the loaded glass in one step,while 95.3%of Mo was precipitated as molybdate and directly recovered with high separation factors(SF_(Mo/Ni)594.8,SF_(Mo/Al)8718.2)in one step.Moreover,the broadband near-infrared luminescence(1150-1700 nm)of glass–ceramics was triggered by Ni^(2+)in the octahedral crystal structure of Me_(3)O_(5)(Me=Mg,Al,Ti)by meltingannealing-crystallization processes,which provided it the potential to be applied in tunable lasers and broadband optical amplifiers for the wavelength-division-multiplexing transmission systems.The Ni^(2+)-doping mechanism was calculated using molecular dynamics simulations.This work emphasized the maximization of the reuse value for each metal resource from hazardous wastes while reducing the burden on the environment and achieving the recycling of rare metal resources with re-valorization.展开更多
Volatile organic compounds(VOCs)exhausted from industrial processes are the major atmospheric pollutants,which could destroy the ecological environment and make hazards to human health seriously.Catalytic oxidation is...Volatile organic compounds(VOCs)exhausted from industrial processes are the major atmospheric pollutants,which could destroy the ecological environment and make hazards to human health seriously.Catalytic oxidation is regarded as the most competitive strategy for the efficient elimination of low-concentration VOCs.Supported noble metal catalysts are preferred catalysts due to their excellent low-temperature catalytic activity.To further lower the cost of catalysts,single atom catalysts(SAC)have been fabricated and extensively studied for application in VOCs oxidation due to their 100%atom-utilization efficiency and unique catalytic performance.In this review,we comprehensively summarize the recent advances in supported noble metal(e.g.,Pt,Pd,Au,and Ag)catalysts and SAC for VOCs oxidation since 2015.Firstly,this paper focuses on some important influencing factors that affect the activity of supported noble metal catalysts,including particle size,valence state and dispersion of noble metals,properties of the support,metal oxide/ion modification,preparation method,and pretreatment conditions of catalysts.Secondly,we briefly summarize the catalytic performance of SAC for typical VOCs.Finally,we conclude the key influencing factors and provide the prospects and challenges of VOCs oxidation.展开更多
Themanganese-cobalt mixed oxide nanorodswere fabricated using a hydrothermalmethod with different metal precursors(KMnO_(4)and MnSO_(4)·H_(2)O for MnOx and Co(NO3)2>6H_(2)O and CoCl_(2)>6H_(2)O for Co_(3)O_...Themanganese-cobalt mixed oxide nanorodswere fabricated using a hydrothermalmethod with different metal precursors(KMnO_(4)and MnSO_(4)·H_(2)O for MnOx and Co(NO3)2>6H_(2)O and CoCl_(2)>6H_(2)O for Co_(3)O_(4)).Bamboo-like MnO_(2)>Co_(3)O_(4)(B-MnO_(2)>Co_(3)O_(4)(S))was derived from repeated hydrothermal treatments with Co_(3)O_(4)@MnO_(2)and MnSO_(4)>H_(2)O,whereas Co_(3)O_(4)@MnO_(2)nanorods were derived from hydrothermal treatment with Co_(3)O_(4)nanorods and KMnO_(4).The study shows that manganese oxide was tetragonal,while the cobalt oxide was found to be cubic in the crystalline arrangement.Mn surface ions were present in multiple oxidation states(e.g.,Mn^(4+)and Mn^(3+))and surface oxygen deficiencies.The content of adsorbed oxygen species and reducibility at low temperature declined in the sequence of BMnO_(2)>Co_(3)O_(4)(S)>Co_(3)O_(4)@MnO_(2)>MnO_(2)>Co_(3)O_(4),matching the changing trend in activity.Among all the samples,B-MnO_(2)>Co_(3)O_(4)(S)showed the preeminent catalytic performance for the oxidation of toluene(T10%=187℃,T50%=276℃,and T90%=339℃).In addition,the B-MnO_(2)>Co_(3)O_(4)(S)sample also exhibited good H_(2)O^(-),CO_(2)^(-),and SO_(2)^(-)resistant performance.The good catalytic performance of B-MnO_(2)>Co_(3)O_(4)(S)is due to the high concentration of adsorbed oxygen species and good reducibility at low temperature.Toluene oxidation over B-MnO_(2)>Co_(3)O_(4)(S)proceeds through the adsorption of O_(2)and toluene to form O∗,OH∗,and H_(2)C(C6H5)∗species,which then react to produce benzyl alcohol,benzoic acid,and benzaldehyde,ultimately converting to CO_(2)and H_(2)O.The findings suggest that B-MnO_(2)>Co_(3)O_(4)(S)has promising potential for use as an effective catalyst in practical applications.展开更多
This study investigates the anodic dissolution and electrochemical behavior of molybdenum in a NaCl-KCl molten salt system at 1023 K.The anodic dissolution process was systematically analyzed,revealing a sequential ox...This study investigates the anodic dissolution and electrochemical behavior of molybdenum in a NaCl-KCl molten salt system at 1023 K.The anodic dissolution process was systematically analyzed,revealing a sequential oxidation pathway of molybdenum into high-valence ions(Mo^(6+),Mo^(5+),Mo^(4+))under vary-ing electrolysis potentials.Electrochemical Impedance Spectroscopy(EIS)demonstrated that the dissolu-tion is governed by both charge transfer and diffusion mechanisms,with reduced impedance at higher potentials facilitating molybdenum dissolution.The reduction behavior of dissolved molybdenum ions was further explored using cyclic voltammetry(CV)and square wave voltammetry(SWV),confirming a multi-step reduction process controlled by diffusion and high reversibility.Nucleation studies using chronoamperometry established that molybdenum deposition follows an instantaneous nucleation mech-anism.Morphological analysis of cathodic deposits revealed that current density significantly influences particle size,transitioning from nano-sized spherical particles to larger equiaxed crystals with increasing current density.These findings provide a comprehensive understanding of molybdenum’s electrochemical properties in molten salts,offering valuable insights for optimizing electrolysis processes and advancing molybdenum-based material production.展开更多
Electrocatalytic CO_(2)reduction reaction(CO_(2)RR)driven by renewable electricity is crucial for sustainable energy cycles and carbon neutrality.Developing cost-effective and efficient electrocatalysts remains a key ...Electrocatalytic CO_(2)reduction reaction(CO_(2)RR)driven by renewable electricity is crucial for sustainable energy cycles and carbon neutrality.Developing cost-effective and efficient electrocatalysts remains a key challenge.Herein,we report a fluorine-regulated Ni single-atom catalyst(NiFN-900)prepared by self-assembly of biomass and phthalocyanine molecules,and the subsequent controllable pyrolysis process,which exhibits remarkable CO_(2)RR performance,achieving industrial-level current density(>200 mA cm^(-2))and Faradaic efficiency(>90%)toward the CO_(2)-to-CO conversion under pH-universal conditions.Detailed theoretical analysis revealed that the synergistic effectsof pyrrolic N-coordinated Ni sites and the semi-ionic C-F bonds simultaneously optimize the adsorption of ^(*)CooH intermediates by d-orbital modulation and suppress the hydrogen evolution reaction by altering surface affinity of ^(*)H species.This dual functionality enables exceptional pH-universal CO_(2)RR performance.Our low-cost,biomass-derived approach offers scalable electrocatalyst design for practical CO_(2)utilizations.展开更多
Increasing the sintering rate of powder compact is a critical challenge of powder metallurgical materials,and adjusting component distribution in particles aggregate present significant effect on the microstructure of...Increasing the sintering rate of powder compact is a critical challenge of powder metallurgical materials,and adjusting component distribution in particles aggregate present significant effect on the microstructure of sintered product,especially for multi-phase compact with local heterogeneity.Here,a case study of W–Ni–Co powder compact was adopted to illustrate the novel strategy to enhance the sintering of multi-phase compact with desired microstructure by adjusting the particle configurations.The plasma synthesis route was developed for the first time to independently adjust the configurations of W–Ni–Co nanopowders with core-shell and homogeneous structures,which facilitates to ascertain the sintering response induced exclusively by particle configurations.Comparison on sintering response further indicates that core-shell powder presents greatly promoted sintering than homogeneous one,and full-dense and uniform compact with grain size of 1.37μm was obtained by solid sintering,which is several to dozens of times smaller than that obtained by conventional liquid sintering.Theoretical and experimental Investigation on elemental immigration visualized the distinct mass diffusion behavior of powder compacts,and clarified the mass transport path promoted densification mechanism determined by powder configurations.Importantly,full-coherent phase interface induced superior strength and plasticity in alloy sintered using core-shell powder,which highlights the importance of microstructural regulation on improving the mechanical property that superior than most of previously reported tungsten heavy alloys.In summary,this work paves a new way for fast sintering of multi-phase compacts,and provides intrinsic understandings on densification mechanism of powder compact.展开更多
基金supported by the National Natu-ral Science Foundation of China(No.52174342)the Beijing Nat-ural Science Foundation(No.2232044)the Beijing Munic-ipal Education Commission Research Plan General Project(No.KM202410005009).
文摘We demonstrate a case study of Ce-doped yttrium aluminum garnet(YAG)phosphor to illustrate a novel plasma route for the synthesis of multicomponent materials with addressing morphology and structural control.The presented strategy was started directly from liquid precursors without any precipitating agents,and an innovative growth mechanism was proposed to explain the formation of monodispersed spherical particles with an adjusted size distribution.Homogeneous elemental distribution close to that of liquid precursors was also achieved due to the thermal nonequilibrium effect in plasma.Benefiting from the structural feature of the obtained product,a low transformation temperature of 1100℃for YAG phase was obtained and final products exhibit the highest photoluminescence intensity with rather low Ce doping of 0.5 wt.%,together with excellent thermal stability of 92%preservation of initial emission at 473 K.This work well illustrates the advance of plasma strategy in formation of multicomponent com-pounds with excellent performances,and its potential for large-scale production due to the transient and in-flight synthesis process.
基金supported by the National Natural Science Foundation of China(Nos.U2341209 and 52130407).
文摘A novel trace nickel(Ni)doped tungsten(W)matrix with coated Ni on W grains was prepared by powder metallurgy method.The introduction of Ni can inhibit the reaction between W and barium-calcium aluminates(Ba-Ca aluminates)during the impregnation process of the matrix.After cathode activation,the surface Ba:O molar ratio is 0.88:1.00,much higher than the Ba dispenser cathode without Ni doping.The XPS results of the cathode surface showed that the metallic Ba appeared on the activated cathode surface,forming dipoles with oxygen,and effectively reducing the cathode surface work function.The pulse electron emission current density at 1100℃_(b)(brightness temperature)was 18.26 A/cm^(2),and the calculated work function was 1.97 eV.It has a low evaporation rate and the accelerated lifetime test predict a lifetime of over 160000 h.First-principles calculations showed that the charge transfer and dipole moment in the NiW-BaO system were both increased compared to the Ba dispenser cathode,thus improving the emission performance of the Ni-W mixed matrix cathode.
基金support of the Research and Development Program in Key Areas of Guangdong Province,China(No.2019B090907001)the Science and Technology Program of Guangdong Province,China(No.2014B010129002)the National Key R&D Program of China(No.2017YFB0305800)。
文摘The densification characterization,phase constitution,precipitation evolution and mechanical performance of Al−Mg−Sc−Zr alloy processed by laser powder bed fusion(LPBF)were systematically investigated.Moreover,the evolution of phase constitution and precipitation behavior after heat treatment were characterized by using X-ray diffraction(XRD)and transmission electron microscope(TEM)analysis.The ultimate tensile strength(UTS)of as-built samples ranged from 396.8 to 414.6 MPa as the scanning speed decreased from 1600 to 1000 mm/s.After post heat treatment,the yield strength(YS)increased to(513.1±1.3)MPa,while the UTS increased from(414.6±5.1)to(539.2±1.5)MPa.The significant improvement of mechanical performance was ascribed to the formation of secondary Al3(Sc,Zr)precipitates.
基金supported by the National Key R&D Program of China(No.2021YFB3501102).
文摘Porous carbon microspheres are widely regarded as a superior CO_(2) adsorbent due to their exceptional efficiency and affordability.However,better adsorption performance is very attractive for porous carbon microspheres.And modification of the pore structure is one of the effective strategies.In this study,multi-cavity mesoporous carbon microspheres were successfully synthesized by the synergistic method of soft and hard templates,during which a phenolic resin with superior thermal stability was employed as the carbon precursor and a mixture of silica sol and F108 as the mesoporous template.Carbon microspheres with multi-cavity mesoporous structures were prepared,and all the samples showed highly even mesopores,with diameters around 12 nm.The diameter of these microspheres decreased from 396.8 nm to about 182.5 nm with the increase of silica sol.After CO_(2) activation,these novel carbon microspheres(APCF0.5-S1.75)demonstrated high specific surface area(983.3 m^(2)/g)and remarkable CO_(2) uptake of 4.93 mmol/g at 0℃ and1 bar.This could be attributed to the unique multi-cavity structure,which offers uniform mesoporous pore channels,minimal CO_(2) transport of and a greater number of active sites for CO_(2) adsorption.
文摘The chemical reaction between lanthanum oxide and molybdenum carbide was studied by thermodynamic calculation, thermal analysis and in situ X ray Photoelectron Spectroscopy. The theoretical results show that at the environment allowing for the evaporation of lanthanum, such as in high vacuum, La 2O 3 in the La 2O 3 Mo materials can be reduced to metallic lanthanum by molybdenum carbide (Mo 2C). To confirm the conclusion, many analysis methods such as XRD, SPS, and TG DTA were taken. The experimental results show that the chemical state of lanthanum changes during heating. It was proved, for the first time, that reacted metallic lanthanum appears at the surface of this kind of material at high temperature.
基金supported by the National Natural Science Foundation of China(51902007)。
文摘Water pollution regarding dyes and heavy metal ions is crucial facing the world.How to effectively separate these contaminants from water has been a key issue.Graphene oxide(GO)promises the greenwater world as a long-lasting spotlight adsorbent material and therefore,harnessing GO has been the research hotspot for over a decade.The state of GO as well as its surface functional groups plays an important role in adsorption.And the way of preparation and structural modification matters to the performance of GO.In this review,the significance of the state of existence of stock GO and surface functional groups is explored in terms of preparation,structural modification,and adsorption.Besides,various adsorbates for GO adsorption are also involved,the discussion of which is rarely established elsewhere.
基金financially supported by the National Natural Science Foundation of China(Nos.50973025,51373045 and 51303044)Fundamental Research Funds for the Central Universities(2013HGCH0013)+2 种基金Specialized Research Fund for the Doctoral Program of Higher Education(SRFDP,20130111120013)Research Foundation for Returned Overseas Chinese Scholars of the Ministry of Education of ChinaAnhui Province’s Natural Scientific Foundation(1408085QE80)
文摘We report on the preparation of a well-defined star-shaped tricationic ionic liquid possessing three arms of poly（ethylene glycol） functionalized imidazolium rings. Remarkable solubility was found in most of the organic solvents we used. Thermogravimetric analysis（TGA） exhibited excellent thermal stability and two distinct decomposition temperatures were attributed to two kinds of chemical degradation. Differential scanning calorimetry（DSC） was further employed to investigate the thermal phase transitions, that three different signals（Tg, Tc, and Tm） were shown upon the second heating process. Moreover, CH2Cl2 solution of the ionic liquid expressed an excitation-wavelength dependent fluorescence response, leading to the facile modulation of photoluminescence behavior. This work represents an example of utilizing molecular design to construct novel ionic liquids and endow further potential to be used in the engineering materials.
基金supported by The Key Laboratory of Advanced Functional Materials, Ministry of Education of China, Beijing University of Technologythe National Natural Science Foundation of China (NSFC, 52070006)。
文摘The design and synthesis of non-precious metal dual-functional electrocatalysts through the modulation of electronic structure are important for the development of renewable hydrogen energy.Herein,MnS_(2)/MnO_(2)-CC heterostructure dual-functional catalysts with ultrathin nanosheets were prepared by a twostep electrodeposition method for efficient acidic hydrogen evolution reaction(HER) and degradation of organic wastewater(such as methylene blue(MB)).The electronic structure of Mn atoms at the MnS_(2)/MnO_(2)-CC heterostructure interface is reconfigured under the joint action of S and O atoms.Theoretical calculations show that the Mn d-band electron distribution in MnS_(2)/MnO_(2)-CC catalyst has higher occupied states near the Fermi level compared to the MnO_(2) and MnS_(2) catalysts,which indicates that MnS_(2)/MnO_(2)-CC catalyst has better electron transfer capability and catalytic activity.The MnS_(2)/MnO_(2)-CC catalysts require overpotential of only 66 and 116 mV to reach current density of 10 and 100 mA cm^(-2)in MB/H_(2)SO_(4) media.The MnS_(2)/MnO_(2)-CC catalyst also has a low Tafel slope(26.72 mV dec^(-1)) and excellent stability(the performance does not decay after 20 h of testing).In addition,the MB removal efficiency of the MnS_(2)/MnO_(2)-CC catalyst with a better kinetic rate(0.0226) can reach 97.76%,which is much higher than that of the MnO_(x)-CC catalyst(72.10%).This strategy provides a new way to develop efficient and stable non-precious metal dual-functional electrocatalysts for HER and organic wastewater degradation.
基金supported by the Natural Science Foundation of China(22106007 and U23A20120)Beijing Natural Science Foundation(8244060)+2 种基金China Postdoctoral Science Foundation(2023M730143)R&D Program of BeijingMunicipal Education Commission(KZ202210005011)Natural Science Foundation of Hebei Province(B2021208033).
文摘Due to the greenhouse effect caused by carbon dioxide(CO_(2))emission,much attention has been paid for the removal of CO_(2).Porous liquids(PLs),as new type of liquid materials,have obvious advantages in mass and heat transfer,which are widely used in gas adsorption and sep-aration.Metal–organic frameworks(MOFs)with merits like large surface area,inherent porous structure and adjustable topology have been considered as one of the best candidates for PLs construction.This review presents the state-of-the-art status on the fabrication strategy of MOFs-based PLs and their CO_(2) absorption and utilization performance,and the positive effects of porosity and functional modification on the absorption-desorption property,selectivity of target product,and regeneration ability are well summarized.Finally,the challenges and prospects for MOFs-based PLs in the optimization of preparation,the coupling of multiple removal techniques,the in situ characterization methods,the regeneration and cycle stability,the environmental impact as well as expansion of application are proposed.
基金financially supported by the National Natural Science Foundation of China(No.52174342)Beijing Natural Sci-ence Foundation(No.2232044)Beijing Municipal Education Commission Research Plan General Project(No.KM202410005009).
文摘In this work,silicon-carbon hybrid materials were adopted as an example to illustrate the novel strategy to in situ construct heterostructure with adjustable microstructure.Based on the temperature-dependent thermodynamics and kinetics of reaction between Si and C,the processes for Si nanocrystals growth and C decoration were coupled at different zones of plasma flame according to its temperature and velocity fields by theoretical modeling,aiming to intentionally suppress the formation of undesirable carbide,and enable adjusting the microstructure of each counterpart separately in transient process.As a result,well-controlled Si/C nanocomposites,including nanospheres and nanowires with core-shell structures,were achieved,and this continuous and in-flight route is also potential for large-scale production.Further investigation on the electrochemical properties highlights the advantage of as proposed strategy to efficiently construct heterostructures with superior performance for various applications.
基金Project supported by the National Key Research and Development Program of China(2021YFB3503003,2021YFB3503100,2022YFB3505401)。
文摘The microstructure of(Nd,Ce)-Fe-B sintered magnets with different diffusion depths was characterized by a magnetic force microscope,and the relationship between the magnetic properties and the local structure of grain boundary diffused magnets is discussed.The domains perpendicular to the c-axis(easy magnetization direction)show a typical maze-like pattern,while those parallel to the c-axis show the characte ristics of plate domains.The significant gradient change is shown in the concentration of Dy with the direction of diffusion from the surface to the interior.Dy diffuses along grain boundaries and(Dy,Nd)_(2)Fe_(14)B layer with a high anisotropy field formed around the grains.Through in-situ electron probe micro-analysis/magnetic force microscopy(EPMA/MFM),it is found that the average domain width decreases,and the proportion of single domain grains increases as diffusion depth increases.This is caused by both the change of concentration and distribution of Dy.The grain boundary diffusion process changes the microstructure and microchemistry inside the magnet,and these local magnetism differences can be reflected by the configuration of the magnetic domain structure.
基金supported by Shenzhen Key Laboratory of Advanced Functional Carbon Materials Research and Comprehensive Application(Grant No.ZDSYS20220527171407017).
文摘The sodium-iodine(Na-I)battery exhibits significant potential as an alternative energy storage device to the lithium-ion battery.However,its development is hindered by inadequate electrical and thermal stability,as well as the dissolution and shuttling of polyiodide.In this study,we report a preparation method for melamine carbon sponge(MC)via carbonizing a commercially available kitchen sponge.It was revealed that the as-prepared MC,composed of unique self-growing carbon nanotubes,could provide both physical and chemical adsorption capabilities for intermediate polyiodides to improve the electrochemical performance of NaI.Consequently,the NaI/MC electrode effectively minimized polyiodide dissolution and reduced the electrochemical impedance.The NaI/MC cathode demonstrated a high average discharge capacity of 92.75 mAh·g^(–1)over 200 cycles while maintaining a coulombic efficiency of 94%.The research findings from our study have promising applications in Na-I batteries.
基金supported by the National Natural Science Foundation of China(92163107,52171061,and 52371128)the National Key Research and Development Program of China(2022YFB3708800 and 2021YFB3501502).
文摘Immiscible bimetal systems,of which tungsten–copper(W–Cu)is a typical representative,have crucial applications in fields requiring both mechanical and physical properties.Nevertheless,it is a major challenge to determine how to give full play to the advantages of the two phases of the bimetal and achieve outstanding comprehensive properties.In this study,an ultrafine-grained W–Cu bimetal with spatially connected Cu and specific Wislands was fabricated through a designed powder-mixing process and subsequent rapid low-temperature sintering.The prepared bimetal concurrently has a high yield strength,large plastic strain,and high electrical conductivity.The stress distribution and strain response of individual phases in different types of W–Cu bimetals under loading were quantified by means of a simulation.The high yield strength of the reported bimetal results from the microstructure refinement and high contiguity of the grains in the W islands,which enhance the contribution of W to the total plastic deformation of the bimetal.The high electrical conductivity is attributed to the increased mean free path of the Cu and the reduced proportion of phase boundaries due to the specific phase combination of W islands and Cu.This work provides new insight into modulating phase configuration in immiscible metallic composites to achieve high-level multi-objective properties.
基金the National Key Research and Development Program of China(Nos.2021YFB3704202,2021YFB3704205)R&D Program of Beijing Municipal Education Commission,China(No.KM 202110005010)+2 种基金Beijing Natural Science Foundation,China(No.2202009)National Natural Science Foundation of China(No.51621003)Basic Research Program of Jiangsu Province,China(No.BK20191148).
文摘A heterogeneous structure composed of elongated primaryαand secondaryαgrains with a size of 670 nm was produced by subjecting the bimodal microstructure of a titanium alloy to hot rolling,annealing,and aging treatments.This heterogeneous structure exhibited significantly improved strength owing to a combination of heterogeneous deformation-induced strengthening and dislocation strengthening.A short-duration high-temperature heat treatment facilitated a synergistic enhancement of yield strength and elongation at both room temperature and 650℃.The fracture elongation at room temperature and 650℃ increased by 36.7% and 130.4%,respectively,compared with that of bimodal microstructure.The stacking of geometrically necessary dislocations with a single slip system at the phase boundary and the longer effective slip length of the dislocations are the reasons for the significant improvement in elongation.The elongated primary α phase in lamellar bimodal microstructure,composed of multiple primary α grains,has better resistance to the anti-fatigue crack initiation effect.
基金financially supported by the National Natural Science Foundation of China for Distinguished Young Scholar(No.52025042)。
文摘Hazardous wastes from the production of cleaner fuels,spent hydrodesulfurization(HDS)catalysts,pose a threat to the environment and the sustainability of rare metal resources.However,conventional recovery approaches are limited by long processes,easy generation of waste liquids,and difficult reuse of recovery products.Herein,a SiO_(2)-Na_(2)O-B_(2)O_(3)-MgO-TiO_(2)glass phase extraction system was proposed for the full-component recycle from spent MoNi/γ-Al_(2)O_(3)catalysts to the materials,including the individual recovery of Mo and the synthesis of Ni^(2+)-doped glass–ceramics.96.7%of Ni and 99.8%of Al were extracted into the loaded glass in one step,while 95.3%of Mo was precipitated as molybdate and directly recovered with high separation factors(SF_(Mo/Ni)594.8,SF_(Mo/Al)8718.2)in one step.Moreover,the broadband near-infrared luminescence(1150-1700 nm)of glass–ceramics was triggered by Ni^(2+)in the octahedral crystal structure of Me_(3)O_(5)(Me=Mg,Al,Ti)by meltingannealing-crystallization processes,which provided it the potential to be applied in tunable lasers and broadband optical amplifiers for the wavelength-division-multiplexing transmission systems.The Ni^(2+)-doping mechanism was calculated using molecular dynamics simulations.This work emphasized the maximization of the reuse value for each metal resource from hazardous wastes while reducing the burden on the environment and achieving the recycling of rare metal resources with re-valorization.
基金supported by Beijing Natural Science Foundation(No.8244060)China Postdoctoral Science Foundation(No.2023M730143)+3 种基金the National Natural Science Foundation of China(No.22425601)the National Key R&D Program of China(No.2023YFB3810801)Beijing Nova Program(No.20240484659)the R&D Program of Beijing Municipal Education Commission(No.KZ202210005011).
文摘Volatile organic compounds(VOCs)exhausted from industrial processes are the major atmospheric pollutants,which could destroy the ecological environment and make hazards to human health seriously.Catalytic oxidation is regarded as the most competitive strategy for the efficient elimination of low-concentration VOCs.Supported noble metal catalysts are preferred catalysts due to their excellent low-temperature catalytic activity.To further lower the cost of catalysts,single atom catalysts(SAC)have been fabricated and extensively studied for application in VOCs oxidation due to their 100%atom-utilization efficiency and unique catalytic performance.In this review,we comprehensively summarize the recent advances in supported noble metal(e.g.,Pt,Pd,Au,and Ag)catalysts and SAC for VOCs oxidation since 2015.Firstly,this paper focuses on some important influencing factors that affect the activity of supported noble metal catalysts,including particle size,valence state and dispersion of noble metals,properties of the support,metal oxide/ion modification,preparation method,and pretreatment conditions of catalysts.Secondly,we briefly summarize the catalytic performance of SAC for typical VOCs.Finally,we conclude the key influencing factors and provide the prospects and challenges of VOCs oxidation.
基金supported by the National Natural Science Foundation Committee of China-Liaoning Provincial People’s Government Joint Fund(No.U1908204)the National Natural Science Foundation of China(Nos.21876006 and 21976009)+2 种基金the Natural Science Foundation of Beijing Municipal Commission of Education(No.KM201710005004)the Development Program for the Youth Outstanding-Notch Talent of Beijing Municipal Commission of Education(No.CIT&TCD201904019)the Foundation on the Creative Research Team Construction Promotion Project of Beijing Municipal Institutions(No.IDHT20190503).
文摘Themanganese-cobalt mixed oxide nanorodswere fabricated using a hydrothermalmethod with different metal precursors(KMnO_(4)and MnSO_(4)·H_(2)O for MnOx and Co(NO3)2>6H_(2)O and CoCl_(2)>6H_(2)O for Co_(3)O_(4)).Bamboo-like MnO_(2)>Co_(3)O_(4)(B-MnO_(2)>Co_(3)O_(4)(S))was derived from repeated hydrothermal treatments with Co_(3)O_(4)@MnO_(2)and MnSO_(4)>H_(2)O,whereas Co_(3)O_(4)@MnO_(2)nanorods were derived from hydrothermal treatment with Co_(3)O_(4)nanorods and KMnO_(4).The study shows that manganese oxide was tetragonal,while the cobalt oxide was found to be cubic in the crystalline arrangement.Mn surface ions were present in multiple oxidation states(e.g.,Mn^(4+)and Mn^(3+))and surface oxygen deficiencies.The content of adsorbed oxygen species and reducibility at low temperature declined in the sequence of BMnO_(2)>Co_(3)O_(4)(S)>Co_(3)O_(4)@MnO_(2)>MnO_(2)>Co_(3)O_(4),matching the changing trend in activity.Among all the samples,B-MnO_(2)>Co_(3)O_(4)(S)showed the preeminent catalytic performance for the oxidation of toluene(T10%=187℃,T50%=276℃,and T90%=339℃).In addition,the B-MnO_(2)>Co_(3)O_(4)(S)sample also exhibited good H_(2)O^(-),CO_(2)^(-),and SO_(2)^(-)resistant performance.The good catalytic performance of B-MnO_(2)>Co_(3)O_(4)(S)is due to the high concentration of adsorbed oxygen species and good reducibility at low temperature.Toluene oxidation over B-MnO_(2)>Co_(3)O_(4)(S)proceeds through the adsorption of O_(2)and toluene to form O∗,OH∗,and H_(2)C(C6H5)∗species,which then react to produce benzyl alcohol,benzoic acid,and benzaldehyde,ultimately converting to CO_(2)and H_(2)O.The findings suggest that B-MnO_(2)>Co_(3)O_(4)(S)has promising potential for use as an effective catalyst in practical applications.
基金financially supported by the National Natural Science Foundation of China for Distinguished Young Scholar(No.52025042)the Open Fund of State Key Laboratory of Advanced Metallurgy(No.KF24-12)。
文摘This study investigates the anodic dissolution and electrochemical behavior of molybdenum in a NaCl-KCl molten salt system at 1023 K.The anodic dissolution process was systematically analyzed,revealing a sequential oxidation pathway of molybdenum into high-valence ions(Mo^(6+),Mo^(5+),Mo^(4+))under vary-ing electrolysis potentials.Electrochemical Impedance Spectroscopy(EIS)demonstrated that the dissolu-tion is governed by both charge transfer and diffusion mechanisms,with reduced impedance at higher potentials facilitating molybdenum dissolution.The reduction behavior of dissolved molybdenum ions was further explored using cyclic voltammetry(CV)and square wave voltammetry(SWV),confirming a multi-step reduction process controlled by diffusion and high reversibility.Nucleation studies using chronoamperometry established that molybdenum deposition follows an instantaneous nucleation mech-anism.Morphological analysis of cathodic deposits revealed that current density significantly influences particle size,transitioning from nano-sized spherical particles to larger equiaxed crystals with increasing current density.These findings provide a comprehensive understanding of molybdenum’s electrochemical properties in molten salts,offering valuable insights for optimizing electrolysis processes and advancing molybdenum-based material production.
基金support of the National Nat-ural Science Foundation of China(NSFC)(22372039 and 22305247)the Fuzhou University Testing Fund of precious apparatus(2025T022).
文摘Electrocatalytic CO_(2)reduction reaction(CO_(2)RR)driven by renewable electricity is crucial for sustainable energy cycles and carbon neutrality.Developing cost-effective and efficient electrocatalysts remains a key challenge.Herein,we report a fluorine-regulated Ni single-atom catalyst(NiFN-900)prepared by self-assembly of biomass and phthalocyanine molecules,and the subsequent controllable pyrolysis process,which exhibits remarkable CO_(2)RR performance,achieving industrial-level current density(>200 mA cm^(-2))and Faradaic efficiency(>90%)toward the CO_(2)-to-CO conversion under pH-universal conditions.Detailed theoretical analysis revealed that the synergistic effectsof pyrrolic N-coordinated Ni sites and the semi-ionic C-F bonds simultaneously optimize the adsorption of ^(*)CooH intermediates by d-orbital modulation and suppress the hydrogen evolution reaction by altering surface affinity of ^(*)H species.This dual functionality enables exceptional pH-universal CO_(2)RR performance.Our low-cost,biomass-derived approach offers scalable electrocatalyst design for practical CO_(2)utilizations.
基金supported by the National Natural Science Foundation of China(No.52130407,52174342,52441408)Beijing Natural Science Foundation(No.2232044,IS23050).
文摘Increasing the sintering rate of powder compact is a critical challenge of powder metallurgical materials,and adjusting component distribution in particles aggregate present significant effect on the microstructure of sintered product,especially for multi-phase compact with local heterogeneity.Here,a case study of W–Ni–Co powder compact was adopted to illustrate the novel strategy to enhance the sintering of multi-phase compact with desired microstructure by adjusting the particle configurations.The plasma synthesis route was developed for the first time to independently adjust the configurations of W–Ni–Co nanopowders with core-shell and homogeneous structures,which facilitates to ascertain the sintering response induced exclusively by particle configurations.Comparison on sintering response further indicates that core-shell powder presents greatly promoted sintering than homogeneous one,and full-dense and uniform compact with grain size of 1.37μm was obtained by solid sintering,which is several to dozens of times smaller than that obtained by conventional liquid sintering.Theoretical and experimental Investigation on elemental immigration visualized the distinct mass diffusion behavior of powder compacts,and clarified the mass transport path promoted densification mechanism determined by powder configurations.Importantly,full-coherent phase interface induced superior strength and plasticity in alloy sintered using core-shell powder,which highlights the importance of microstructural regulation on improving the mechanical property that superior than most of previously reported tungsten heavy alloys.In summary,this work paves a new way for fast sintering of multi-phase compacts,and provides intrinsic understandings on densification mechanism of powder compact.
