Defect engineering presents great promise in addressing lower specific capacity,sluggish diffusion kinetics and poor cycling life issues in energy storage devices.Herein,multidimensional(0D/2D/3D) structural defects a...Defect engineering presents great promise in addressing lower specific capacity,sluggish diffusion kinetics and poor cycling life issues in energy storage devices.Herein,multidimensional(0D/2D/3D) structural defects are constructed in WO_(3)/MoO_(2) simultaneously via competing for and sharing with O atoms during simple hydrothermal process.OD and 2D defects tailor local electron,activating more sites and generating built-in electric fields to yield ion reservoir,meanwhile,3D defect owning lower anisotropic property tailors Mg^(2+) diffusion channels to fully exploit Mg^(2+) adsorbed sites induced by OD and 2D defects,enhance the kinetics and maintain structural stability.Benefitted from synergistic effect of 0D/2D/3D structural defects,the designed WO_(3)/MoO_(2) shows the higher specific capacity(112.8 mA h g^(-1) at 50 mA g^(-1) with average attenuation rate per cycle of 0.068%),superior rate capability and excellent cycling stability(specific capacity retention of 80% after 1500 cycles at 1000 mA g^(-1)).This strategy provides design ideas of introducing multidimensional structural defects for tailoring local electron and microstructure to improve energy storage property.展开更多
ZrW_(2)O_(8)is a typical isotropic negative thermal expansion material with cubic structure.However,quenching preparation,pressure phase transition and metastable structure influence its practical applications.Adoptin...ZrW_(2)O_(8)is a typical isotropic negative thermal expansion material with cubic structure.However,quenching preparation,pressure phase transition and metastable structure influence its practical applications.Adopting P to part-substitute W for ZrW_(2-x)P_(x)O_(8-0.5x)has decreased the sintering temperature and avoided the quenching process.When x=0.1,ZrW_(1.9)P_(0.1)O_(7.95)with a stable cubic structure can be obtained at 1150℃.The thermal expansion coefficient is tailored with the P content,and phase transition temperature is lowered.When x=0.5,thermal expansion coefficient attains-13.6×10^(-6)℃^(-1),ZrW_(1.5)P_(0.5)O_(7.75)exhibits enhance negative thermal expansion property.The difference of electronegativity leads to the decrease of phase transition temperature with the increase of P content.The different radii of ions lead to new structure of materials when P substitutes more.The results suggest that the P atom plays the stabilization role in the crystal structure of ZrW_(2-x)P_(x)O_(8-0.5x).展开更多
Sodium-ion batteries stand a chance of enabling fast charging ability and long lifespan while operating at low temperature(low-T).However,sluggish kinetics and aggravated dendrites present two major challenges for ano...Sodium-ion batteries stand a chance of enabling fast charging ability and long lifespan while operating at low temperature(low-T).However,sluggish kinetics and aggravated dendrites present two major challenges for anodes to achieve the goal at low-T.Herein,we propose an interlayer confined strategy for tailoring nitrogen terminals on Ti_(3)C_(2) MXene(Ti_(3)C_(2)-N_(funct)) to address these issues.The introduction of nitrogen terminals endows Ti_(3)C_(2)-N_(funct) with large interlayer space and charge redistribution,improved conductivity and sufficient adsorption sites for Na^(+),which improves the possibility of Ti_(3)C_(2) for accommodating more Na atoms,further enhancing the Na^(+) storage capability of Ti_(3)C_(2).As revealed,Ti_(3)C_(2)-N_(funct) not only possesses a lower Na-ion diffusion energy barrier and charge trans-fer activation energy,but also exhibits Na^(+)-solvent co-intercalation behavior to circumvent a high de-solvation energy barrier at low-T.Besides,the solid electrolyte interface dominated by inorganic com-pounds is more beneficial for the Na^(+)transfer at the electrode/electrolyte interface.Compared with of the unmodified sample,Ti_(3)C_(2)-Nfunct exhibits a twofold capacity(201 mAh g^(-1)),fast-charging ability(18 min at 80% capacity retention),and great superiority in cycle life(80.9%@5000 cycles)at -25℃.When coupling with Na_(3)V_(2)(PO_(4))_(2)F_(3) cathode,the Ti_(3)C_(2)-N_(funct)//NVPF exhibits high energy density and cycle stability at -25℃.展开更多
The modification of nanostructured materials is of great interest due to controllable and unusual inherent properties in such materials. Single phase Fe doped Zn O nanostructures have been fabricated through simple, v...The modification of nanostructured materials is of great interest due to controllable and unusual inherent properties in such materials. Single phase Fe doped Zn O nanostructures have been fabricated through simple, versatile and quick low temperature solution route with reproducible results. The amount of Fe dopant is found to play a significant role for the growth of crystal dimension. The effect of changes in the morphology can be obviously observed in the structural and micro-structural investigations, which may be due to a driving force induced by dipole-dipole interaction. The band gap of Zn O nanostructures is highly shifted towards the visible range with increase of Fe contents, while ferromagnetic properties have been significantly improved.The prepared nanostructures have been found to be nontoxic to SH-SY5 Y Cells. The present study clearly indicates that the Fe doping provides an effective way of tailoring the crystal dimension, optical band-gap and ferromagnetic properties of Zn O nanostructure-materials with nontoxic nature, which make them potential for visible light activated photocatalyst to overcome environmental pollution, fabricate spintronics devices and biosafe drug delivery agent.展开更多
Achieving high-quality perovskite crystal films is a critical prerequisite in boosting solar cell efficiency and improving the device stability,but the delicate control of nucleation and growth of the perovskite film ...Achieving high-quality perovskite crystal films is a critical prerequisite in boosting solar cell efficiency and improving the device stability,but the delicate control of nucleation and growth of the perovskite film remains limited success.Herein,a facile but effective strategy has been developed to finely tailor the crystallization of thermally stable cesium/formamidinium(Cs/FA)based perovskite via partially replacing PbI2 with PbCl2 in the precursor solution.The incorporation of chlorine into the perovskite crystal lattice derived from PbCl2 changes the crystallization process and improves the crystal quality,which further results in the formation of larger crystal grains compared to the control sample.The larger crystal grains with high crystallinity lead to reduced grain boundaries,suppressed non-radiative recombination,and enhanced photoluminescence lifetime.Under the optimized conditions,the methylammonium free perovskite solar cells(PSCs)delivers a champion power conversion efficiency(PCE)of 21.30%with an open-circuit voltage as high as 1.18 V,which is one of the highest efficiencies for Cs/FA based PSCs up to now.Importantly,the unencapsulated PSC devices retain more than 95%and 81%of their original PCEs even after long-term(over one year)storage under ambient conditions or 2000 h’s thermal aging at 850C in a nitrogen atmosphere,respectively.展开更多
A new material tailoring method for spherical and cylindrical vessels made of functionally graded materials (FGMs) is presented.It is assumed that the FG material is composed of an A1-SiC metallic-matrix composite.A u...A new material tailoring method for spherical and cylindrical vessels made of functionally graded materials (FGMs) is presented.It is assumed that the FG material is composed of an A1-SiC metallic-matrix composite.A uniform ratio of inplane shear stress to yield strength [φ(r)] is used as the design criterion to utilize the maximum capacity of the vessel.The aim is to find a distribution of SiC particles in the radial direction,i.e.,f(r),that achieves a uniform index φ(r) =const,through the wall thickness of the internally pressurized spherical or cylindrical vessel.Both the Mori-Tanaka and rule-of-mixtures homogenization schemes are used to express the effective elastic module and Poisson's ratio.Moreover,the strength of the composite is expressed based on the rule of mixtures.Besides,finite element simulation is carried out to verify the accuracy of the analytical solution.The effects of input parameters such as the internal pressure,strength of the SiC particles,ratio of in-plane shear stress to effective yield strength,and choice of homogenization scheme on the tailored distribution of the SiC volume fraction in the radial direction are also investigated.展开更多
Using ab initio density functional theory calculations, we explore the three most stable structural phases, namely, α,β, and cubic(c) phases, of two-dimensional(2D) antimonene, as well as its isoelectronic counterpa...Using ab initio density functional theory calculations, we explore the three most stable structural phases, namely, α,β, and cubic(c) phases, of two-dimensional(2D) antimonene, as well as its isoelectronic counterparts SnTe and InI. We find that the band gap increases monotonically from Sb to SnTe to InI along with an increase in ionicity, independent of the structural phases. The band gaps of this material family cover the entire visible-light energy spectrum, ranging from 0.26 eV to 3.37 eV, rendering them promising candidates for optoelectronic applications. Meanwhile, band-edge positions of these materials are explored and all three types of band alignments can be achieved through properly combining antimonene with its isoelectronic counterparts to form heterostructures. The richness in electronic properties for this isoelectronic material family sheds light on possibilities to tailor the fundamental band gap of antimonene via lateral alloying or forming vertical heterostructures.展开更多
Metals have been mankind’s most essential materials for thousands of years.In recent years,however,innovation-driven development of major national security strategy and core areas of the national economy is highly im...Metals have been mankind’s most essential materials for thousands of years.In recent years,however,innovation-driven development of major national security strategy and core areas of the national economy is highly impeded by a shortage of advanced higher-strength-toughness metals.One of the main reasons is that metals inherently exhibit the inverted-relationship of strength-toughness.The emergence of two types of disordered metals:amorphous alloys and high entropy alloys,provides a fully-fresh strategy for strength-toughening by tailoring the topological and/or chemical disorder.In this paper,we first briefly review the history of strength-toughening of metals,and summarize the development route-map.We then introduce amorphous alloys and high entropy alloys,as well as some case studies in tailoring disorder to successfully achieve coexisting high strength and high ductility/toughness.Relevant challenges that await further research are summarized in concluding remarks.展开更多
Tuning the bandgap in layered transition metal dichalcogenides(TMDCs) is crucial for their versatile applications in many fields. The ternary formation is a viable method to tune the bandgap as well as other intrinsic...Tuning the bandgap in layered transition metal dichalcogenides(TMDCs) is crucial for their versatile applications in many fields. The ternary formation is a viable method to tune the bandgap as well as other intrinsic properties of TMDCs, because the multi-elemental characteristics provide additional tunability at the atomic level and advantageously alter the physical properties of TMDCs. Herein, ternary Ti_(x)Zr_(1-x)Se_(2) single crystals were synthesized using the chemical-vapor-transport method. The changes in electronic structures of ZrSe_(2) induced by Ti substitution were revealed using angle-resolved photoemission spectroscopy. Our data show that at a low level of Ti substitution, the bandgap of Ti_(x)Zr_(1-x)Se_(2) decreases monotonically, and the electronic system undergoes a transition from a semiconducting to a metallic state without a significant variation of dispersions of valence bands. Meanwhile, the size of spin-orbit splitting dominated by Se 4p orbitals decreases with the increase of Ti doping. Our work shows a convenient way to alter the bandgap and spin-orbit coupling in TMDCs at the low level of substitution of transition metals.展开更多
This paper presents experimental and numerical investigation on the parameters effecting energy absorption capability of composite tubular structures at oblique loading to improve crashworthiness performance. Various ...This paper presents experimental and numerical investigation on the parameters effecting energy absorption capability of composite tubular structures at oblique loading to improve crashworthiness performance. Various inclined angles of 5°, 10°, 20° and 30° were selected for the study of off-axis loading. The results indicate that by increasing the lateral inclination angle the mean crushing force and also energy absorption capability of all tested sections decreased. From design perspective, it is necessary to investigate the parameters effecting this phenomenon. The off-axis loading effect that causes significant reduction in energy absorption was investigated and the effected parameters were improved to increase energy absorption capability. To establish this study, 10° off-axis loading was chosen to illustrate the obtained improvement in energy absorption capability. Five cases were studied with combinations of ply-orientation and flat trimming with 45° chamfer. This method was applied to the integrated 10° off-axis loading and the final results showed significant improvement in energy absorption capability of composite absorbers. Finite element model (FEM) was developed to simulate the crushing process of axial and off-axis composite section in LS-DYNA and the results were in good agreement with the experimental data.展开更多
In Romania,CNTAC delegation had a deep understanding to this important Eastern European Country along'The Belt and Road'.The textile and garment industry is the traditional pillar industry in Romania.It takes ...In Romania,CNTAC delegation had a deep understanding to this important Eastern European Country along'The Belt and Road'.The textile and garment industry is the traditional pillar industry in Romania.It takes an important status in its national economy and foreign trade.Romania is also an important market展开更多
It is well known that'Hong Band Spirit'has left an indelible mark on Ningbo clothing.'Why can Hong Band Culture survive a hundred years?''Because of the great proficiency and hard work of the tailo...It is well known that'Hong Band Spirit'has left an indelible mark on Ningbo clothing.'Why can Hong Band Culture survive a hundred years?''Because of the great proficiency and hard work of the tailors.'During the 21st Ningbo International Fashion Fair held in Ningbo from October 19th to 22nd,2017,Romon invited two old experienced tailors-展开更多
Poor flowability of printable powders and long preparation cycles are the main challenges in the selective laser sintering(SLS)of chopped carbon fiber(C_(f))reinforced silicon carbide(SiC)composites with complex struc...Poor flowability of printable powders and long preparation cycles are the main challenges in the selective laser sintering(SLS)of chopped carbon fiber(C_(f))reinforced silicon carbide(SiC)composites with complex structures.In this study,we develop an efficient and novel processing route in the fabrication of lightweight SiC composites via the SLS of phenolic resin(PR)and Cr powders with the addition of a-SiC particles combined with the one-step reactive melt infiltration(RMI).The effects of a-SiC addition on the microstructural evolution of the C_(f)/SiC/PR printed bodies,C_(f)/SiC/C green bodies,and derived SiC composites were investigated.The results indicate that the added a-SiC particles play an important role in enhancing the flowability of raw powders,reducing the porosity.increasing the reliability of the C/SiC/C green bodies,and contributing to improving the microstructure homogeneity and mechanical properties of the SiC composites.The maximum density,flexural strength,and fracture toughness(Kic)of the SiC composites are 2.749±0.006 g·cm^(3),266±5 MPa,and 3.30±0.06 MPa-m,respectively.The coefficient of thermal expansion(CTE,a)of the SiC composites is approximately 4.29×10^(-6)K^(-1)from room temperature(RT)to 900℃,and the thermal conductivity(x)is in the range of 80.15-92.48 W·m^(-1)·K^(-1)at RT.The high-temperature strength of the SiC composites increase to 287±18 MPa up to 1200℃.This study provides a novel as well as feasible tactic for the preparation of high-quality printable powders as well as lightweight,high-strength,and high-x SiC composites with complex structures by the SLS and RMI.展开更多
Conventional wrought Mg alloys,such as AZ31 and ZK60 rolled plates,usually exhibit significantly low tensile yield strength in the thickness direction.This can be attributed to the high activity of{10-12}tension twinn...Conventional wrought Mg alloys,such as AZ31 and ZK60 rolled plates,usually exhibit significantly low tensile yield strength in the thickness direction.This can be attributed to the high activity of{10-12}tension twinning due to the strong basal texture(<0001>//ND,normal direction).In this work,the tensile yield strength in the ND of the as-rolled(AR)AZ31 plate increased from 50 to 150 MPa(increased by 200%)via simple processing,i.e.,pre-tension and rolling-annealing(PTRA)treatment.The strong basal texture(<0001>//ND)of the AR plate was changed into a weakened fiber texture(<0001>⊥ND).The evolution of microstructures during PTRA treatment and the activated deformation modes during uniaxial tension were studied quantitatively and statistically by the means of intergranular misorientation(IM)and in-grain misorientation axes(IGMA)analysis.The results indicate that various twin variants,as well as{10-12}-{10-12}secondary twins,were activated during pre-tension and rolling,and most residual matrix was consumed by twins after annealing.The dominated deformation modes in tension changed from{10-12}tension twinning(the AR sample)to prismatic slip(the PTRA sample)in the early tensile deformation.The underlying formation mechanism of the fiber texture and corresponding strengthening mechanism were discussed.展开更多
Depsides and depsidones have attracted attention for biosynthetic studies due to their broad biological activities and structural diversity.Previous structure-activity relationships indicated that triple halogenated d...Depsides and depsidones have attracted attention for biosynthetic studies due to their broad biological activities and structural diversity.Previous structure-activity relationships indicated that triple halogenated depsidones display the best anti-pathogenic activity.However,the gene cluster and the tailoring steps responsible for halogenated depsidone nornidulin(3)remain enigmatic.In this study,we disclosed the complete biosynthetic pathway of the halogenated depsidone through in vivo gene disruption,heterologous expression and in vitro biochemical experiments.We demonstrated an unusual depside skeleton biosynthesis process mediated by both highly-reducing polyketide synthase and nonreducing polyketide synthase,which is distinct from the common depside skeleton biosynthesis.This skeleton was subsequently modified by two in-cluster enzymes DepG and DepF for the ether bond formation and decarboxylation,respectively.In addition,the decarboxylase DepF exhibited substrate promiscuity for different scaffold substrates.Finally,and interestingly,we discovered a halogenase encoded remotely from the biosynthetic gene cluster,which catalyzes triple-halogenation to produce the active end product nornidulin(3).These discoveries provide new insights for further understanding the biosynthesis of depsidones and their derivatives.展开更多
Lowering the cost while maintaining the highly catalytic performance is greatly beneficial for the development of commercial fuel cells and metal-air batteries.Compared with platinum,palladium holds a stronger oxygen ...Lowering the cost while maintaining the highly catalytic performance is greatly beneficial for the development of commercial fuel cells and metal-air batteries.Compared with platinum,palladium holds a stronger oxygen affinity and high abundance on earth,endowing it a promising alternative to platinum in anion-exchange membrane fuel cells.However,the sluggish oxygen reduction reaction of palladium still remains a great issue and requires the design of stable and efficient palladium-based electrocatalysts.Here,we report the solvothermal/hydrothermal reduction method to prepare a series of PdAg_(x)nanowires.The prepared PdAg_(x)NWs exhibit hollow structure,which greatly improves the utilization of Pd atoms,offering an outstanding ORR performance.Specifically,PdAg_(2)NWs exhibit an onset potential of 0.92 V and mass activity of 350.7 mA mgPd^(-1)at 0.7 V vs.RHE for ORR in 0.1 M KOH solution.This work provides a novel approach for the construction of hollow NWs and their subsequent applications in other electrocatalytic reactions.展开更多
Although spatial charge separation between different facets of semiconductor crystals has been recognized as a general strategy in photocatalysis, the vital role of crystal morphology symmetry in charge separation pro...Although spatial charge separation between different facets of semiconductor crystals has been recognized as a general strategy in photocatalysis, the vital role of crystal morphology symmetry in charge separation properties still remains elusive. Herein,taking monoclinic bismuth vanadate(BiVO_(4)) as a platform, we found distinct charge separation difference via rationally tailoring the morphology symmetry from octahedral to truncated octahedral crystals. For octahedral BiVO_(4), photogenerated electrons and holes can be separated between edges and quasi-equivalent facets. However, as for truncated octahedral crystals,photogenerated electrons tend to transfer to {010} facets while photogenerated holes prefer to accumulate on {120} facets, thus realizing the spatial separation of photogenerated charge between different facets. Morphology tailoring of BiVO_(4) crystals leads to a significantly improved photogenerated charge separation efficiency and photocatalytic water oxidation activity. The built-in electric field for driving the separation of photogenerated electrons and holes is considered to be modulated by tuning the morphology symmetry of BiVO_(4) crystals. This work discloses the significant roles of morphology symmetry in photogenerated charge separation and facilitates the rational design of artificial photocatalysts.展开更多
Covalent organic frameworks(COFs)provide a unique platform with tunable structures allowing precise control of pore sizes,shapes and functions.The key to synthesizing COFs with desired structures is to precisely contr...Covalent organic frameworks(COFs)provide a unique platform with tunable structures allowing precise control of pore sizes,shapes and functions.The key to synthesizing COFs with desired structures is to precisely control the conformation and geometry of building blocks as well as the growth direction of COFs.To achieve this,steric effects are noteworthy that may have a significant impact on the assembly of COFs.Specifically,the introduction of sterically demanding substituents or bulky groups into monomers of COFs will lead to intramolecular conformational changes and intermolecular repulsions,which induce structural changes in COFs,including changes in torsion angles,interlayer distances,stacking modes and topologies of 2D COFs,and changes in spatial nodes,interpenetration and topologies of 3D COFs.This review will help to understand the impacts of steric effects on the structures of COFs and to take them into extensive consideration in the design and synthesis of COFs with novel functionalities and structural attributes.展开更多
The structural,morphological and optical properties of single-phase polycrystalline La2-xSrxNiMnO6(x=0,0.3 and 0.5),synthesized by solid state reaction were investigated.The samples were characterized by X-ray diffrac...The structural,morphological and optical properties of single-phase polycrystalline La2-xSrxNiMnO6(x=0,0.3 and 0.5),synthesized by solid state reaction were investigated.The samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM)/energy dispersive analysis of X-rays(EDAX),Raman spectroscopy and diffuse reflectance spectroscopy(DRS)to elucidate the role of A-site Sr-doping in double perovskite La2 NiMnO6.Rietveld analysis of XRD patterns revealed that all the samples have monoclinic structure with space group P21/n.Positive gradient in the Williamson Hall plots revealed the presence of tensile strain in all the samples.The morphological studies revealed that average grain size increases along with appreciable decrease in porosity with Sr doping.The Ni/Mn antisite disorder was introduced in the La2 NiMnO6 by Sr-doping confirmed by an increase in the full width at half maximum(FWHM)and decrease in intensity of the Raman modes at around 540 and 665 cm-1 which correspond to the antisymmetric stretching and symmetric stretching modes,respectively.DRS results reveal that the band gap in La2 NiMnO6 can be tuned down by Sr-doping to a value of1.37 eV(very close to 1.40 eV,considered as optimum value for better efficiency of a solar cell).Thus,Sr-doped La2 NiMnO6 may be of prime importance for applications in solar cells.展开更多
Poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP)receives increasing attention in membrane separation field based on its advantages such as high mechanical strength,thermal and chemical stability.However,cont...Poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP)receives increasing attention in membrane separation field based on its advantages such as high mechanical strength,thermal and chemical stability.However,controlling the microporous structure is still challenging.In this work,we attempted to tailor the morphology of PVDF-HFP membrane via a one-step reactive vapor induced phase separation method.Namely,PVDF-HFP was dissolved in a volatile solvent and then was cast in an ammonia water vapor atmosphere.After complete evaporation of solvent,membranes with adjustable porous structure were prepared,and the microstructures of the membranes were analyzed by scanning electron microscopy,Fourier transform infrared spectroscopy,X-ray photoelectron spectroscopy and X-ray diffraction characterizations.Based on the results,a mechanism of dehydrofluorination induced cross-linking of PVDF-HFP has been suggested to understand the morphology tailoring.To our knowledge,this is the first report of one-step reactive vapor induced phase separation strategy to tailor morphology of PVDF-HFP membrane.In addition,the membranes prepared in the ammonia water vapor exhibited enhanced mechanical strength and achieved satisfactory separation efficiency for water-in-oil emulsions,suggesting promising potential.展开更多
基金supported by the National Natural Science Foundation of China under Grant No. 52072196, 52002199, 52002200, 52102106Major Basic Research Program of Natural Science Foundation of Shandong Province under Grant No. ZR2020ZD09+5 种基金the Natural Science Foundation of Shandong Province under Grant No. ZR2019BEM042, ZR2020QE063the Innovation and Technology Program of Shandong Province under Grant No. 2020KJA004the Taishan Scholars Program of Shandong Province under No. ts201511034Postdoctoral Program in Qingdao under No. QDBSH20220202019the innovation Capability Improvement Project of Small and Medium-sized Technological Enterprises in Shandong Province under No. 2021TSGC1156the Financial Support From the Qingdao West Coast New Area Science and Technology Project under No. 2020-104。
文摘Defect engineering presents great promise in addressing lower specific capacity,sluggish diffusion kinetics and poor cycling life issues in energy storage devices.Herein,multidimensional(0D/2D/3D) structural defects are constructed in WO_(3)/MoO_(2) simultaneously via competing for and sharing with O atoms during simple hydrothermal process.OD and 2D defects tailor local electron,activating more sites and generating built-in electric fields to yield ion reservoir,meanwhile,3D defect owning lower anisotropic property tailors Mg^(2+) diffusion channels to fully exploit Mg^(2+) adsorbed sites induced by OD and 2D defects,enhance the kinetics and maintain structural stability.Benefitted from synergistic effect of 0D/2D/3D structural defects,the designed WO_(3)/MoO_(2) shows the higher specific capacity(112.8 mA h g^(-1) at 50 mA g^(-1) with average attenuation rate per cycle of 0.068%),superior rate capability and excellent cycling stability(specific capacity retention of 80% after 1500 cycles at 1000 mA g^(-1)).This strategy provides design ideas of introducing multidimensional structural defects for tailoring local electron and microstructure to improve energy storage property.
基金Project supported by the Key Scientific and Technological Research Projects of Henan Province,China(Grant Nos.222102220021 and 222102220056)。
文摘ZrW_(2)O_(8)is a typical isotropic negative thermal expansion material with cubic structure.However,quenching preparation,pressure phase transition and metastable structure influence its practical applications.Adopting P to part-substitute W for ZrW_(2-x)P_(x)O_(8-0.5x)has decreased the sintering temperature and avoided the quenching process.When x=0.1,ZrW_(1.9)P_(0.1)O_(7.95)with a stable cubic structure can be obtained at 1150℃.The thermal expansion coefficient is tailored with the P content,and phase transition temperature is lowered.When x=0.5,thermal expansion coefficient attains-13.6×10^(-6)℃^(-1),ZrW_(1.5)P_(0.5)O_(7.75)exhibits enhance negative thermal expansion property.The difference of electronegativity leads to the decrease of phase transition temperature with the increase of P content.The different radii of ions lead to new structure of materials when P substitutes more.The results suggest that the P atom plays the stabilization role in the crystal structure of ZrW_(2-x)P_(x)O_(8-0.5x).
基金the National Natural Sci-ence Foundation of China(Grant Nos.21673064,51902072 and 22109033)Heilongjiang Touyan Team(Grant No.HITTY-20190033)+1 种基金Fundamental Research Funds for the Central Universities(Grant Nos.HIT.NSRIF.2019040 and 2019041)State Key Laboratory of Urban Water Resource and Environment(Harbin Institute of Technology)(Grant No.2020 DX11).
文摘Sodium-ion batteries stand a chance of enabling fast charging ability and long lifespan while operating at low temperature(low-T).However,sluggish kinetics and aggravated dendrites present two major challenges for anodes to achieve the goal at low-T.Herein,we propose an interlayer confined strategy for tailoring nitrogen terminals on Ti_(3)C_(2) MXene(Ti_(3)C_(2)-N_(funct)) to address these issues.The introduction of nitrogen terminals endows Ti_(3)C_(2)-N_(funct) with large interlayer space and charge redistribution,improved conductivity and sufficient adsorption sites for Na^(+),which improves the possibility of Ti_(3)C_(2) for accommodating more Na atoms,further enhancing the Na^(+) storage capability of Ti_(3)C_(2).As revealed,Ti_(3)C_(2)-N_(funct) not only possesses a lower Na-ion diffusion energy barrier and charge trans-fer activation energy,but also exhibits Na^(+)-solvent co-intercalation behavior to circumvent a high de-solvation energy barrier at low-T.Besides,the solid electrolyte interface dominated by inorganic com-pounds is more beneficial for the Na^(+)transfer at the electrode/electrolyte interface.Compared with of the unmodified sample,Ti_(3)C_(2)-Nfunct exhibits a twofold capacity(201 mAh g^(-1)),fast-charging ability(18 min at 80% capacity retention),and great superiority in cycle life(80.9%@5000 cycles)at -25℃.When coupling with Na_(3)V_(2)(PO_(4))_(2)F_(3) cathode,the Ti_(3)C_(2)-N_(funct)//NVPF exhibits high energy density and cycle stability at -25℃.
基金supported by Higher Education Commission of Pakistan, National Basic Research Program of China (2010CB934602)National Science Foundation of China (51171007 and 51271009)
文摘The modification of nanostructured materials is of great interest due to controllable and unusual inherent properties in such materials. Single phase Fe doped Zn O nanostructures have been fabricated through simple, versatile and quick low temperature solution route with reproducible results. The amount of Fe dopant is found to play a significant role for the growth of crystal dimension. The effect of changes in the morphology can be obviously observed in the structural and micro-structural investigations, which may be due to a driving force induced by dipole-dipole interaction. The band gap of Zn O nanostructures is highly shifted towards the visible range with increase of Fe contents, while ferromagnetic properties have been significantly improved.The prepared nanostructures have been found to be nontoxic to SH-SY5 Y Cells. The present study clearly indicates that the Fe doping provides an effective way of tailoring the crystal dimension, optical band-gap and ferromagnetic properties of Zn O nanostructure-materials with nontoxic nature, which make them potential for visible light activated photocatalyst to overcome environmental pollution, fabricate spintronics devices and biosafe drug delivery agent.
基金support from the National Natural Science Foundation of China(Grant Nos.21773218 and 61904166)。
文摘Achieving high-quality perovskite crystal films is a critical prerequisite in boosting solar cell efficiency and improving the device stability,but the delicate control of nucleation and growth of the perovskite film remains limited success.Herein,a facile but effective strategy has been developed to finely tailor the crystallization of thermally stable cesium/formamidinium(Cs/FA)based perovskite via partially replacing PbI2 with PbCl2 in the precursor solution.The incorporation of chlorine into the perovskite crystal lattice derived from PbCl2 changes the crystallization process and improves the crystal quality,which further results in the formation of larger crystal grains compared to the control sample.The larger crystal grains with high crystallinity lead to reduced grain boundaries,suppressed non-radiative recombination,and enhanced photoluminescence lifetime.Under the optimized conditions,the methylammonium free perovskite solar cells(PSCs)delivers a champion power conversion efficiency(PCE)of 21.30%with an open-circuit voltage as high as 1.18 V,which is one of the highest efficiencies for Cs/FA based PSCs up to now.Importantly,the unencapsulated PSC devices retain more than 95%and 81%of their original PCEs even after long-term(over one year)storage under ambient conditions or 2000 h’s thermal aging at 850C in a nitrogen atmosphere,respectively.
文摘A new material tailoring method for spherical and cylindrical vessels made of functionally graded materials (FGMs) is presented.It is assumed that the FG material is composed of an A1-SiC metallic-matrix composite.A uniform ratio of inplane shear stress to yield strength [φ(r)] is used as the design criterion to utilize the maximum capacity of the vessel.The aim is to find a distribution of SiC particles in the radial direction,i.e.,f(r),that achieves a uniform index φ(r) =const,through the wall thickness of the internally pressurized spherical or cylindrical vessel.Both the Mori-Tanaka and rule-of-mixtures homogenization schemes are used to express the effective elastic module and Poisson's ratio.Moreover,the strength of the composite is expressed based on the rule of mixtures.Besides,finite element simulation is carried out to verify the accuracy of the analytical solution.The effects of input parameters such as the internal pressure,strength of the SiC particles,ratio of in-plane shear stress to effective yield strength,and choice of homogenization scheme on the tailored distribution of the SiC volume fraction in the radial direction are also investigated.
基金Project supported by the National Natural Science Foundation of China(Grant No.51702146)the College Students’Innovation and Entrepreneurship Projects,China(Grant No.201710148000072)Liaoning Province Doctor Startup Fund,China(Grant No.201601325)。
文摘Using ab initio density functional theory calculations, we explore the three most stable structural phases, namely, α,β, and cubic(c) phases, of two-dimensional(2D) antimonene, as well as its isoelectronic counterparts SnTe and InI. We find that the band gap increases monotonically from Sb to SnTe to InI along with an increase in ionicity, independent of the structural phases. The band gaps of this material family cover the entire visible-light energy spectrum, ranging from 0.26 eV to 3.37 eV, rendering them promising candidates for optoelectronic applications. Meanwhile, band-edge positions of these materials are explored and all three types of band alignments can be achieved through properly combining antimonene with its isoelectronic counterparts to form heterostructures. The richness in electronic properties for this isoelectronic material family sheds light on possibilities to tailor the fundamental band gap of antimonene via lateral alloying or forming vertical heterostructures.
基金This work was supported by the National Outstanding Youth Science Fund Project of National Natural Science Foundation of China(NSFC)(No.12125206)the NSFC Basic Science Center for“Multiscale Problems in Nonlinear Mechanics”(No.11988102)the NSFC(Nos.11972345 and 11790292).
文摘Metals have been mankind’s most essential materials for thousands of years.In recent years,however,innovation-driven development of major national security strategy and core areas of the national economy is highly impeded by a shortage of advanced higher-strength-toughness metals.One of the main reasons is that metals inherently exhibit the inverted-relationship of strength-toughness.The emergence of two types of disordered metals:amorphous alloys and high entropy alloys,provides a fully-fresh strategy for strength-toughening by tailoring the topological and/or chemical disorder.In this paper,we first briefly review the history of strength-toughening of metals,and summarize the development route-map.We then introduce amorphous alloys and high entropy alloys,as well as some case studies in tailoring disorder to successfully achieve coexisting high strength and high ductility/toughness.Relevant challenges that await further research are summarized in concluding remarks.
基金supported by the National Key R&D Program of China (Grant No. 2017YFA0402901)the National Natural Science Foundation of China (Grant No. U2032153)+2 种基金the International Partnership Program (Grant No. 211134KYSB20190063)the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDB25000000)the USTC Research Funds of the Double First-Class Initiative (Grant No. YD2310002004)。
文摘Tuning the bandgap in layered transition metal dichalcogenides(TMDCs) is crucial for their versatile applications in many fields. The ternary formation is a viable method to tune the bandgap as well as other intrinsic properties of TMDCs, because the multi-elemental characteristics provide additional tunability at the atomic level and advantageously alter the physical properties of TMDCs. Herein, ternary Ti_(x)Zr_(1-x)Se_(2) single crystals were synthesized using the chemical-vapor-transport method. The changes in electronic structures of ZrSe_(2) induced by Ti substitution were revealed using angle-resolved photoemission spectroscopy. Our data show that at a low level of Ti substitution, the bandgap of Ti_(x)Zr_(1-x)Se_(2) decreases monotonically, and the electronic system undergoes a transition from a semiconducting to a metallic state without a significant variation of dispersions of valence bands. Meanwhile, the size of spin-orbit splitting dominated by Se 4p orbitals decreases with the increase of Ti doping. Our work shows a convenient way to alter the bandgap and spin-orbit coupling in TMDCs at the low level of substitution of transition metals.
文摘This paper presents experimental and numerical investigation on the parameters effecting energy absorption capability of composite tubular structures at oblique loading to improve crashworthiness performance. Various inclined angles of 5°, 10°, 20° and 30° were selected for the study of off-axis loading. The results indicate that by increasing the lateral inclination angle the mean crushing force and also energy absorption capability of all tested sections decreased. From design perspective, it is necessary to investigate the parameters effecting this phenomenon. The off-axis loading effect that causes significant reduction in energy absorption was investigated and the effected parameters were improved to increase energy absorption capability. To establish this study, 10° off-axis loading was chosen to illustrate the obtained improvement in energy absorption capability. Five cases were studied with combinations of ply-orientation and flat trimming with 45° chamfer. This method was applied to the integrated 10° off-axis loading and the final results showed significant improvement in energy absorption capability of composite absorbers. Finite element model (FEM) was developed to simulate the crushing process of axial and off-axis composite section in LS-DYNA and the results were in good agreement with the experimental data.
文摘In Romania,CNTAC delegation had a deep understanding to this important Eastern European Country along'The Belt and Road'.The textile and garment industry is the traditional pillar industry in Romania.It takes an important status in its national economy and foreign trade.Romania is also an important market
文摘It is well known that'Hong Band Spirit'has left an indelible mark on Ningbo clothing.'Why can Hong Band Culture survive a hundred years?''Because of the great proficiency and hard work of the tailors.'During the 21st Ningbo International Fashion Fair held in Ningbo from October 19th to 22nd,2017,Romon invited two old experienced tailors-
基金supported by the National Natural Science Foundation of China(Nos.52073299,52172077,U22A20129,and 51902329)the National Key R&D Program of China(No.2022YFB3706303)the Youth Innovation Promotion Association CAS(No.2018289).
文摘Poor flowability of printable powders and long preparation cycles are the main challenges in the selective laser sintering(SLS)of chopped carbon fiber(C_(f))reinforced silicon carbide(SiC)composites with complex structures.In this study,we develop an efficient and novel processing route in the fabrication of lightweight SiC composites via the SLS of phenolic resin(PR)and Cr powders with the addition of a-SiC particles combined with the one-step reactive melt infiltration(RMI).The effects of a-SiC addition on the microstructural evolution of the C_(f)/SiC/PR printed bodies,C_(f)/SiC/C green bodies,and derived SiC composites were investigated.The results indicate that the added a-SiC particles play an important role in enhancing the flowability of raw powders,reducing the porosity.increasing the reliability of the C/SiC/C green bodies,and contributing to improving the microstructure homogeneity and mechanical properties of the SiC composites.The maximum density,flexural strength,and fracture toughness(Kic)of the SiC composites are 2.749±0.006 g·cm^(3),266±5 MPa,and 3.30±0.06 MPa-m,respectively.The coefficient of thermal expansion(CTE,a)of the SiC composites is approximately 4.29×10^(-6)K^(-1)from room temperature(RT)to 900℃,and the thermal conductivity(x)is in the range of 80.15-92.48 W·m^(-1)·K^(-1)at RT.The high-temperature strength of the SiC composites increase to 287±18 MPa up to 1200℃.This study provides a novel as well as feasible tactic for the preparation of high-quality printable powders as well as lightweight,high-strength,and high-x SiC composites with complex structures by the SLS and RMI.
基金supported by the National Natural Science Foundation of China(Nos.51575068 and 51501023)the State Key Research and Development Program of MOST,China(No.2016627 YFB0701204)+2 种基金the Fundamental Research Funds for the Central Universities(No.2020CDJDPT001)the Chongqing Natural Science Foundation(Nos.cstc2018jcyjAX0364 and cstc2021jcyj-msxmX0699)the“111”Project of the Ministry of Education(No.B16007).
文摘Conventional wrought Mg alloys,such as AZ31 and ZK60 rolled plates,usually exhibit significantly low tensile yield strength in the thickness direction.This can be attributed to the high activity of{10-12}tension twinning due to the strong basal texture(<0001>//ND,normal direction).In this work,the tensile yield strength in the ND of the as-rolled(AR)AZ31 plate increased from 50 to 150 MPa(increased by 200%)via simple processing,i.e.,pre-tension and rolling-annealing(PTRA)treatment.The strong basal texture(<0001>//ND)of the AR plate was changed into a weakened fiber texture(<0001>⊥ND).The evolution of microstructures during PTRA treatment and the activated deformation modes during uniaxial tension were studied quantitatively and statistically by the means of intergranular misorientation(IM)and in-grain misorientation axes(IGMA)analysis.The results indicate that various twin variants,as well as{10-12}-{10-12}secondary twins,were activated during pre-tension and rolling,and most residual matrix was consumed by twins after annealing.The dominated deformation modes in tension changed from{10-12}tension twinning(the AR sample)to prismatic slip(the PTRA sample)in the early tensile deformation.The underlying formation mechanism of the fiber texture and corresponding strengthening mechanism were discussed.
基金funded by the National Natural Science Foundation of China(22037006,U2106207,22077128)Local Innovation and Entrepreneurship Team Project of Guangdong(2019BT02Y262,China)+4 种基金Key Science and Technology Project of Hainan Province(ZDKJ202018,China)Major Project of Basic and Applied Basic Research of Guangdong Province(2019B030302004,China)Key-Area Research and Development Program of Guangdong Province(2020B1111030005,China)Guangdong Provincial Marine Economic Development(Six Major Marine Undertakings,China)Special Fund Project(GDNRC[2021]54,China)Open Program of Shenzhen Bay Laboratory(SZBL2021080601006,China)。
文摘Depsides and depsidones have attracted attention for biosynthetic studies due to their broad biological activities and structural diversity.Previous structure-activity relationships indicated that triple halogenated depsidones display the best anti-pathogenic activity.However,the gene cluster and the tailoring steps responsible for halogenated depsidone nornidulin(3)remain enigmatic.In this study,we disclosed the complete biosynthetic pathway of the halogenated depsidone through in vivo gene disruption,heterologous expression and in vitro biochemical experiments.We demonstrated an unusual depside skeleton biosynthesis process mediated by both highly-reducing polyketide synthase and nonreducing polyketide synthase,which is distinct from the common depside skeleton biosynthesis.This skeleton was subsequently modified by two in-cluster enzymes DepG and DepF for the ether bond formation and decarboxylation,respectively.In addition,the decarboxylase DepF exhibited substrate promiscuity for different scaffold substrates.Finally,and interestingly,we discovered a halogenase encoded remotely from the biosynthetic gene cluster,which catalyzes triple-halogenation to produce the active end product nornidulin(3).These discoveries provide new insights for further understanding the biosynthesis of depsidones and their derivatives.
基金supported by the National Natural Science Foundation of China(22162006,22102035)Natural Science Foundation of Guangxi Province(2019GXNSFGA245003,2021GXNSFBA220077).
文摘Lowering the cost while maintaining the highly catalytic performance is greatly beneficial for the development of commercial fuel cells and metal-air batteries.Compared with platinum,palladium holds a stronger oxygen affinity and high abundance on earth,endowing it a promising alternative to platinum in anion-exchange membrane fuel cells.However,the sluggish oxygen reduction reaction of palladium still remains a great issue and requires the design of stable and efficient palladium-based electrocatalysts.Here,we report the solvothermal/hydrothermal reduction method to prepare a series of PdAg_(x)nanowires.The prepared PdAg_(x)NWs exhibit hollow structure,which greatly improves the utilization of Pd atoms,offering an outstanding ORR performance.Specifically,PdAg_(2)NWs exhibit an onset potential of 0.92 V and mass activity of 350.7 mA mgPd^(-1)at 0.7 V vs.RHE for ORR in 0.1 M KOH solution.This work provides a novel approach for the construction of hollow NWs and their subsequent applications in other electrocatalytic reactions.
基金supported by the National Key Research and Development Program of China (2021YFA1502300)by the Fundamental Research Funds for the Central Universities (20720220011)+3 种基金conducted by the Fundamental Research Center of Artificial Photosynthesis (FReCAP)financially supported by the National Natural Science Foundation of China (22088102)the support from National Natural Science Foundation of China (22090033, 22272165)Youth Innovation Promotion Association of Chinese Academy of Sciences and the National Youth Talent Support Program。
文摘Although spatial charge separation between different facets of semiconductor crystals has been recognized as a general strategy in photocatalysis, the vital role of crystal morphology symmetry in charge separation properties still remains elusive. Herein,taking monoclinic bismuth vanadate(BiVO_(4)) as a platform, we found distinct charge separation difference via rationally tailoring the morphology symmetry from octahedral to truncated octahedral crystals. For octahedral BiVO_(4), photogenerated electrons and holes can be separated between edges and quasi-equivalent facets. However, as for truncated octahedral crystals,photogenerated electrons tend to transfer to {010} facets while photogenerated holes prefer to accumulate on {120} facets, thus realizing the spatial separation of photogenerated charge between different facets. Morphology tailoring of BiVO_(4) crystals leads to a significantly improved photogenerated charge separation efficiency and photocatalytic water oxidation activity. The built-in electric field for driving the separation of photogenerated electrons and holes is considered to be modulated by tuning the morphology symmetry of BiVO_(4) crystals. This work discloses the significant roles of morphology symmetry in photogenerated charge separation and facilitates the rational design of artificial photocatalysts.
基金supported by the National Natural Science Foundation of China(22225503,U21A20285,21975188,22105149)the support by the fellowship of China National Postdoctoral Program for Innovative Talents(BX2021226)。
文摘Covalent organic frameworks(COFs)provide a unique platform with tunable structures allowing precise control of pore sizes,shapes and functions.The key to synthesizing COFs with desired structures is to precisely control the conformation and geometry of building blocks as well as the growth direction of COFs.To achieve this,steric effects are noteworthy that may have a significant impact on the assembly of COFs.Specifically,the introduction of sterically demanding substituents or bulky groups into monomers of COFs will lead to intramolecular conformational changes and intermolecular repulsions,which induce structural changes in COFs,including changes in torsion angles,interlayer distances,stacking modes and topologies of 2D COFs,and changes in spatial nodes,interpenetration and topologies of 3D COFs.This review will help to understand the impacts of steric effects on the structures of COFs and to take them into extensive consideration in the design and synthesis of COFs with novel functionalities and structural attributes.
基金the full support from our Institute, National Institute of Technology SrinagarMinistry of Human Resource Development (MHRD) India, for the financial support
文摘The structural,morphological and optical properties of single-phase polycrystalline La2-xSrxNiMnO6(x=0,0.3 and 0.5),synthesized by solid state reaction were investigated.The samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM)/energy dispersive analysis of X-rays(EDAX),Raman spectroscopy and diffuse reflectance spectroscopy(DRS)to elucidate the role of A-site Sr-doping in double perovskite La2 NiMnO6.Rietveld analysis of XRD patterns revealed that all the samples have monoclinic structure with space group P21/n.Positive gradient in the Williamson Hall plots revealed the presence of tensile strain in all the samples.The morphological studies revealed that average grain size increases along with appreciable decrease in porosity with Sr doping.The Ni/Mn antisite disorder was introduced in the La2 NiMnO6 by Sr-doping confirmed by an increase in the full width at half maximum(FWHM)and decrease in intensity of the Raman modes at around 540 and 665 cm-1 which correspond to the antisymmetric stretching and symmetric stretching modes,respectively.DRS results reveal that the band gap in La2 NiMnO6 can be tuned down by Sr-doping to a value of1.37 eV(very close to 1.40 eV,considered as optimum value for better efficiency of a solar cell).Thus,Sr-doped La2 NiMnO6 may be of prime importance for applications in solar cells.
基金supported by the Fundamental Research Funds for the Central Universities of China(No.20720200040)the National Natural Science Foundation of China(No.51273166).
文摘Poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP)receives increasing attention in membrane separation field based on its advantages such as high mechanical strength,thermal and chemical stability.However,controlling the microporous structure is still challenging.In this work,we attempted to tailor the morphology of PVDF-HFP membrane via a one-step reactive vapor induced phase separation method.Namely,PVDF-HFP was dissolved in a volatile solvent and then was cast in an ammonia water vapor atmosphere.After complete evaporation of solvent,membranes with adjustable porous structure were prepared,and the microstructures of the membranes were analyzed by scanning electron microscopy,Fourier transform infrared spectroscopy,X-ray photoelectron spectroscopy and X-ray diffraction characterizations.Based on the results,a mechanism of dehydrofluorination induced cross-linking of PVDF-HFP has been suggested to understand the morphology tailoring.To our knowledge,this is the first report of one-step reactive vapor induced phase separation strategy to tailor morphology of PVDF-HFP membrane.In addition,the membranes prepared in the ammonia water vapor exhibited enhanced mechanical strength and achieved satisfactory separation efficiency for water-in-oil emulsions,suggesting promising potential.
