Incorporating a selenium(Se)positive electrode into aluminum(Al)-ion batteries is an effective strategy for improving the overall battery performance.However,the cycling stability of Se positive electrodes has challen...Incorporating a selenium(Se)positive electrode into aluminum(Al)-ion batteries is an effective strategy for improving the overall battery performance.However,the cycling stability of Se positive electrodes has challenges due to the dissolution of intermediate reaction products.In this work,we aim to harness the advantages of Se while reducing its limitations by preparing a core-shell mesoporous carbon hollow sphere with a titanium nitride(C@TiN)host to load 63.9wt%Se as the positive electrode material for Al-Se batteries.Using the physical and chemical confinement offered by the hollow mesoporous carbon and TiN,the obtained core-shell mesoporous carbon hollow spheres coated with Se(Se@C@TiN)display superior utilization of the active material and remarkable cycling stability.As a result,Al-Se batteries equipped with the as-prepared Se@C@TiN composite positive electrodes show an initial discharge specific capacity of 377 mAh·g^(-1)at a current density of 1000 mA·g^(-1)while maintaining a discharge specific capacity of 86.0 mAh·g^(-1)over 200 cycles.This improved cycling performance is ascribed to the high electrical conductivity of the core-shell mesoporous carbon hollow spheres and the unique three-dimensional hierarchical architecture of Se@C@TiN.展开更多
The ternary transitional metal oxide NiCo_2O_4 is a promising anode material for sodium ion batteries due to its high theoretical capacity and superior electrical conductivity. However, its sodium storage capability i...The ternary transitional metal oxide NiCo_2O_4 is a promising anode material for sodium ion batteries due to its high theoretical capacity and superior electrical conductivity. However, its sodium storage capability is severely limited by the sluggish sodiation/desodiation reaction kinetics. Herein, NiCo_2O_4 double-shelled hollow spheres were synthesized via a microwave-assisted, fast solvothermal synthetic procedure in a mixture of isopropanol and glycerol, followed by annealing. Isopropanol played a vital role in the precipitation of nickel and cobalt,and the shrinkage of the glycerol quasi-emulsion under heat treatment was responsible for the formation of the double-shelled nanostructure. The as-synthesized productwas tested as an anode material in a sodium ion battery,was found to exhibit a high reversible specific capacity of 511 m Ahg^(-1) at 100 m Ag^(-1), and deliver high capacity retention after 100 cycles.展开更多
The triple-shelled hollow spheres with optical properties were prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization.After removal the core templates of the poly(styrene),the hollow silic...The triple-shelled hollow spheres with optical properties were prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization.After removal the core templates of the poly(styrene),the hollow silica spheres were obtained.The coating process of poly(methyl methacrylate)(PMMA) on the hollow silica spheres surface via surface RAFT polymerization was performed subsequently.The polymers coated on the hollow spheres surfaces were end-functionalized by trithiocarbonate,and they were used as RAFT agent to proceed the chain extension polymerization using Tb complex as monomer.The samples were characterized by FT-IR,SEM and luminescence spectroscopy respectively.The results indicated that the triple-shelled hollow spheres had been prepared successfully and the average diameter of the hollow core was about 1μm.展开更多
TiO2-coated SnO2 (TCS) hollow spheres, which are new anode materials for lithium ion (Li-ion) batteries, were prepared and characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), transm...TiO2-coated SnO2 (TCS) hollow spheres, which are new anode materials for lithium ion (Li-ion) batteries, were prepared and characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), cyclic voltammetry (CV), and galvanostatic charge/discharge tests. The results obtained from XRD, SEM, and TEM show that TiO2 can be uniforrrdy coated on the surface of SnO2 hollow spheres with the assistance of anionic surfactant. The cyclic voltammograms indicate that both TiO2 and SnO2 exhibit the activity for Li-ion storage. The charge/discharge tests show that the prepared TCS hollow spheres have a higher reversible coulomb efficiency and a better cycling stability than the uncoated SnO2 hollow spheres.展开更多
Abstract: We performed fluidized bed coating ofAl-based nanoeomposite powder-binder suspensions onto polymer substrates. The effects of the type and amount of the binder and nanoparticle additive on the coating proce...Abstract: We performed fluidized bed coating ofAl-based nanoeomposite powder-binder suspensions onto polymer substrates. The effects of the type and amount of the binder and nanoparticle additive on the coating process efficiency and coating characteristics were investigated. The efficiency decreased from 52% to 49% as the processing time increased from 15 to 20 min. However, the amount and thickness of the coating also increased as the processing time and amount of the binder were increased. The addition of nanoparticles to the system decreased the thickness of the coating from 222 to 207 μm when polyvinyl alcohol (PVA) was used as a binder. The suspension containing 3wt% R-4410 binder exhibited the greatest efficiency of 60%.展开更多
Catalyst support is extremely important for future fuel cell devices.In this work,we developed doubleshelled C/TiO2(DSCT)hollow spheres as an excellent catalyst support via a template-directed method.The combination o...Catalyst support is extremely important for future fuel cell devices.In this work,we developed doubleshelled C/TiO2(DSCT)hollow spheres as an excellent catalyst support via a template-directed method.The combination of hollow structure,TiO2 shell and carbon layer results in excellent electron conductivity,electrocatalytic activity,and chemical stability.These uniformed DSCT hollow spheres are used as catalyst support to synthesize Pt/DSCT hollow spheres electrocatalyst.The resulting Pt/DSCT hollow spheres exhibited high catalytic performance with a current density of 462 mA mg^-1 for methanol oxidation reaction,which is 2.52 times higher than that of the commercial Pt/C.Furthermore,the increased tolerance to carbonaceous poisoning with a higher If/Ibratio and a better long-term stability in acid media suggests that the DSCT hollow sphere is a promising C/TiO2-based catalyst support for direct methanol fuel cells applications.展开更多
CaCO3 hollow spheres were prepared easily in anion surfactants (sodium dodecylbenzenesulfonate (SDBS)) and aspartic (Asp) acid binary-additive system by using an easy rapid agitation method. The as-prepared prod...CaCO3 hollow spheres were prepared easily in anion surfactants (sodium dodecylbenzenesulfonate (SDBS)) and aspartic (Asp) acid binary-additive system by using an easy rapid agitation method. The as-prepared products were characterized with scanning electron microscopy (SEM), FT-IR and X-ray diffraction. The results suggested that the CaCO3 hollow spheres have diameters ranging from 1 to 2 μm, and their wall is constituted of many nano-particles. Moreover, the possible formation mechanism of the hollow spherical structure was proposed.展开更多
The controlled synthesis of ZnO hollow spheres is successfully achieved through a facile solvothermal method using a Keggin-type silicotungstic acid(H_4 Si(W_3 O_(10))_4:HSW) as structure directing agent. The f...The controlled synthesis of ZnO hollow spheres is successfully achieved through a facile solvothermal method using a Keggin-type silicotungstic acid(H_4 Si(W_3 O_(10))_4:HSW) as structure directing agent. The formation process of these hollow spheres is proposed based on a variety of controlled experiments. In addition, Au nanoparticles are loaded onto the surface of ZnO hollow spheres. It is found that the Au-loaded ZnO(Au/ZnO) composites exhibit greatly enhanced activity on oxidizing Rhodamine B(Rh B) under simulated UV or visible light irradiation, compared to the pristine ZnO hollow spheres. The improved performance of Au/ZnO heterostructures is mainly attributed to the enhanced optical absorption and the accelerated separation and migration of photogenerated charge carriers. Moreover, the photocatalytic reaction mechanisms are proposed based on the results of electron spin resonance(ESR) analysis, photoelectrochemical measurements, and photocatalytic evaluation. The results and findings are expected to provide significance to the synthesis of noble metal-semiconductor hybrids towards water purification.展开更多
The free vibration of a functionally graded material hollow spheresubmerged in a compress- ible fluid medium is exactly analyzed. Thesphere is assumed to be spherically isotropic with material consta-nts being inhomog...The free vibration of a functionally graded material hollow spheresubmerged in a compress- ible fluid medium is exactly analyzed. Thesphere is assumed to be spherically isotropic with material consta-nts being inhomogeneous along the radial direction. By employing aseparation technique as well as the spherical harmonics expansionmethod, the governing equations are simplified to an uncoupledsecond-order ordinary differential equation, and a coupled system oftwo such equations. Solutions to these equations are given when theelastic constants and the mass density are power functions of theradial coordinate. Numerical examples are finally given to show theeffect of the material gradient on the natural frequencies.展开更多
Monoclinic Cu3V2O7(OH)2·2H2O(copper polyvanadate) hollow spheres were prepared with Na2V6O16·3H2O nanobelts as V-precursor by hydrothermal method. The purity and structure of the products were characteri...Monoclinic Cu3V2O7(OH)2·2H2O(copper polyvanadate) hollow spheres were prepared with Na2V6O16·3H2O nanobelts as V-precursor by hydrothermal method. The purity and structure of the products were characterized by X-ray powder diffraction(XRD), Fourier transform infrared(FTIR) spectroscopy, Raman spectroscopy, thermogravimetric analysis(TGA) and X-ray photoelecton spectroscopy(XPS). The morphology and size were observed by scanning electron microscopy(SEM). We found that the Kagomé staircase-structural copper polyvanadate hollow spheres with an average diameter of 7 μm could be easily synthesized via the reaction of Na2V6O16·3H2O nanobelts with sufficient copper sulfate. The dielectric property of the copper polyvanadate demonstrates that dielectric loss hardly changes when the frequency of applied electric field is higher than 100 kHz. The formation process of the hollow spheres is discussed in detail by the observation of a series of products prepared for different reaction time.展开更多
The effect of magnetic field on the plane vibrations for an elastodynamic orthotropic sphere is studied. Equations of elastodynamic problems of the orthotropic hollow sphere in terms of displacement are solved. The nu...The effect of magnetic field on the plane vibrations for an elastodynamic orthotropic sphere is studied. Equations of elastodynamic problems of the orthotropic hollow sphere in terms of displacement are solved. The numerical results of the frequency equations in the presence of magnetic field are discussed and shown graphically. Compar-isons are made with the result in the presence and absence of magnetic field in the case of orthotropic sphere. The results show that the effect of magnetic field is very pronounced.展开更多
INCO-617 alloy hollow sphere foams with average aperture of about 3 mm and about 0.12 mm wall thickness were fabricated by hollow sphere method.Firstly the wet spheres,which are formed as powder shells from slurry by ...INCO-617 alloy hollow sphere foams with average aperture of about 3 mm and about 0.12 mm wall thickness were fabricated by hollow sphere method.Firstly the wet spheres,which are formed as powder shells from slurry by coating polystyrene balls,were arranged with body-centered cubic(BCC) structure.Subsequently,the sphere stacks were heat-treated in vacuum at 350 ℃ for 40 min to decompose the organic materials,and sintered at different temperatures for different time.The effects of slurry components,sintering temperature and sintering time on the density and porosity of cell wall of hollow sphere foam were studied through Scanning Electron Microscopy.The results show that the densities of INCO-617 alloy hollow sphere foam,increasing with the increase of powder content in slurry,sintering temperature and sintering time,range from 1.112 to 1.216 g·cm-3.Extension of sintering time can reduce the porosity of cell wall,which enhances the compression strength of hollow sphere foam significantly.展开更多
Nanocrystalline MoS2 with hollow spherical morphology has been prepared by the hydrothermal method. The products are characterized by means of X-ray powder diffraction, transmission electron microscopy and high-resol...Nanocrystalline MoS2 with hollow spherical morphology has been prepared by the hydrothermal method. The products are characterized by means of X-ray powder diffraction, transmission electron microscopy and high-resolution transmission electron microscopy. The experimental results give the evidence that the sample is consists of hollow spheres 400~600 nm in diameter, and there is much whisker on the surface of MoS2 hollow sphere.展开更多
A series of basic nitrogen doped carbon hollow spheres(p-N-C) catalysts derived from waste tires were prepared by a green, facile and environmental “leavening” strategy for the catalytic oxidation of pentanethiol. C...A series of basic nitrogen doped carbon hollow spheres(p-N-C) catalysts derived from waste tires were prepared by a green, facile and environmental “leavening” strategy for the catalytic oxidation of pentanethiol. Compared to pristine carbon, the p-N-C has a higher surface curvature conducive to the enrichment of substrates, leading to an excellent catalytic performance. This increased surface curvature of p-N-C was fabricated on the synergistic effect of two foaming agents((NH4)2 C2 O4 and NaHCO3), and the released gas also endows the spherical shell of p-N-C with a hierarchical porous structure, promoting the accessibility of active sites with pentanethiol. Pyridine-like and pyrrolic-like nitrogen atoms were investigated as reactive sites on the p-N-C to accelerate the electron transfer from sulfur to active surface oxygen and enhance the adsorption/oxidation process. As a result, the optimal p-N-C catalyst exhibits superior adsorption and oxidation performance(99.9%) of pentanethiol, outperforming the “unleavened”catalyst(20.8%). This work offers a new avenue for the fabrication of highly efficient materials for the desulfurization of fuel.展开更多
Thermoelastic properties of hollow sphere composites are studied based on the uniform matrix-field concept proposed here. Some connections between local thermal and mechanical fields produced by certain homogeneous bo...Thermoelastic properties of hollow sphere composites are studied based on the uniform matrix-field concept proposed here. Some connections between local thermal and mechanical fields produced by certain homogeneous boundary conditions are derived, and furthermore, exact relations are also obtained between the effective thermoelastic properties of the composites. For a macroscopically isotropic composite with a certain ratio of the outer radius to the inner radius, it is found that the effective bulk modulus and the linear coefficient of thermal expansion can be exactly determined, if the thermal expansion coefficient of the matrix and that of the sphere are the same.展开更多
Zirconia hollow sphere products are ultra-high temperature energy saving lightweight insulating refractories in zirconia system.They not only have the same refractoriness as zirconia products,but also have the advanta...Zirconia hollow sphere products are ultra-high temperature energy saving lightweight insulating refractories in zirconia system.They not only have the same refractoriness as zirconia products,but also have the advantages of low bulk density and excellent thermal insulation properties.Their thermal conductivity is 0.3-0.4 W · m-1 · K-1 only 1/2 of that of the ordinary zirconia products.They are special refractories which can be used steadily up to 2 400 ℃ in oxidation,reduction and vacuum atmospheres.Zirconia hollow sphere products are the best lining refractories for various ultra-high temperature kilns and furnaces of tungsten and molybdenum metal products processing,artificial crystals,and quartz industrial production.展开更多
The unsatisfactory conductivity and large volume variation severely handicap the application of SnO_(2)in sodium-ion batteries(SIBs).Herein,we design unique three-layer structured SnO_(2)@C@TiO_(2)hollow spheres to ta...The unsatisfactory conductivity and large volume variation severely handicap the application of SnO_(2)in sodium-ion batteries(SIBs).Herein,we design unique three-layer structured SnO_(2)@C@TiO_(2)hollow spheres to tackle the above-mentioned issues.The hollow cavity affords empty space to accommodate the volume variation of SnO_(2),while the C and TiO_(2)protecting shells strengthen the structural integrity and enhances the electrical conductivity.As a result,the three-layer structured SnO_(2)@C@TiO_(2)hollow spheres demonstrate enhanced Na storage performances.The SnO_(2)@C@TiO_(2)manifests a reversible capacity two times to that of pristine SnO_(2)hollow spheres.In addition,Ex situ XRD reveals highly reversible alloying and conversion reactions in SnO_(2)@C@TiO_(2)hollow spheres.This study suggests the introduction of a hollow cavity and robust protecting shells is a promising strategy for constructing SIB anode materials.展开更多
β-SiAION hollow spheres were prepared by carbothermal reduction method, using coal fly ash ( 〈 15 μm, 43 - 77 μm, and 〉 100 μm) and active carbon in Some proportion (20% less than theoretical addition, theore...β-SiAION hollow spheres were prepared by carbothermal reduction method, using coal fly ash ( 〈 15 μm, 43 - 77 μm, and 〉 100 μm) and active carbon in Some proportion (20% less than theoretical addition, theoretical addition and 10% excess theoretical addition) as starting materials, putting into alumina crucible in high temperature nitriding furnace after well mixed, and holding at 1 300 ℃, 1 350 ℃, 1 400 ℃, 1 450 ℃, and 1 500 ℃ for 6 h. Effects of temperature, particle size of the microsphere . and addition of active carbon on the phase composition and microstructure of the nitridized products were studied by means of XRD and SEM. The results show that the nitridation reaction starts at 1 300 ℃ ; excess active carbon is necessary to form β-SiAION hollow spheres, and particle size is the important parameter to form the hollow spheres nitridized products β-SiAION; at 1 500 ℃, when the active carbon is 10% in excess, the β-SiAlON hollow spheres, which were prepared using coal fly ash with particle size 〉 100 μm, are featured with rough surface, high hollowness and low density.展开更多
A bi-layer photoanode for dye-sensitized solar cell(DSSC) was fabricated, in which TiO_2 hollow spheres(THSs) were designed as a scattering layer and P25/multi-walled carbon nanotubes(MWNTs) as an under-layer. The THS...A bi-layer photoanode for dye-sensitized solar cell(DSSC) was fabricated, in which TiO_2 hollow spheres(THSs) were designed as a scattering layer and P25/multi-walled carbon nanotubes(MWNTs) as an under-layer. The THSs were synthesized by a sacrifice template method and showed good light scattering ability as an over-layer of the photoanode. MWNTs were mixed with P25 to form an under-layer of the photoanode to improve the electron transmission ability of the photoanode. The power conversion efficiency of this kind of DSSC with bi-layer was enhanced to 5.13 %,which is 14.25 % higher than that of pure P25 DSSC.Graphical Abstract A bi-layer composite photoanode based on P25/MWNTs-THSs with improved light scattering and electron transmission, which will provide a new insight into fabrication and structure design of highly efficient dyesensitized solar cells.展开更多
The separation of variables method was successfully used to resolve the spherically symmetric dynamic thermoelastie problem for a spherically isotropic elastic hollow sphere. Use of the integral transform can be avoid...The separation of variables method was successfully used to resolve the spherically symmetric dynamic thermoelastie problem for a spherically isotropic elastic hollow sphere. Use of the integral transform can be avoided by means of this method, which is also appropriate for an arbitrary thickness hollow sphere subjected to arbitrary thermal and mechanical loads. Numerical results are presented to show the dynamic stress responses in the uniformly heated hollow spheres.展开更多
基金supported by the National Natural Science Foundation of China(No.52374350)China Postdoctoral Science Foundation(Nos.2020M680347 and 2021T140051)the Fundamental Research Funds for the Central Universities(No.FRF-TP-20-045A1)。
文摘Incorporating a selenium(Se)positive electrode into aluminum(Al)-ion batteries is an effective strategy for improving the overall battery performance.However,the cycling stability of Se positive electrodes has challenges due to the dissolution of intermediate reaction products.In this work,we aim to harness the advantages of Se while reducing its limitations by preparing a core-shell mesoporous carbon hollow sphere with a titanium nitride(C@TiN)host to load 63.9wt%Se as the positive electrode material for Al-Se batteries.Using the physical and chemical confinement offered by the hollow mesoporous carbon and TiN,the obtained core-shell mesoporous carbon hollow spheres coated with Se(Se@C@TiN)display superior utilization of the active material and remarkable cycling stability.As a result,Al-Se batteries equipped with the as-prepared Se@C@TiN composite positive electrodes show an initial discharge specific capacity of 377 mAh·g^(-1)at a current density of 1000 mA·g^(-1)while maintaining a discharge specific capacity of 86.0 mAh·g^(-1)over 200 cycles.This improved cycling performance is ascribed to the high electrical conductivity of the core-shell mesoporous carbon hollow spheres and the unique three-dimensional hierarchical architecture of Se@C@TiN.
基金financially supported by the Science Foundation of Sichuan Province(Grant No.2016FZ0070)the Natural Science Foundation of China(NSFC,201476145)the technical support for Materials Characterization from The Analytical and Testing Center of Sichuan University
文摘The ternary transitional metal oxide NiCo_2O_4 is a promising anode material for sodium ion batteries due to its high theoretical capacity and superior electrical conductivity. However, its sodium storage capability is severely limited by the sluggish sodiation/desodiation reaction kinetics. Herein, NiCo_2O_4 double-shelled hollow spheres were synthesized via a microwave-assisted, fast solvothermal synthetic procedure in a mixture of isopropanol and glycerol, followed by annealing. Isopropanol played a vital role in the precipitation of nickel and cobalt,and the shrinkage of the glycerol quasi-emulsion under heat treatment was responsible for the formation of the double-shelled nanostructure. The as-synthesized productwas tested as an anode material in a sodium ion battery,was found to exhibit a high reversible specific capacity of 511 m Ahg^(-1) at 100 m Ag^(-1), and deliver high capacity retention after 100 cycles.
基金a project of Shandong Province Higher Education Science and Technology Program(No.J09LD56)the Scientific Research Start up Fund for Doctor of Liaocheng University.
文摘The triple-shelled hollow spheres with optical properties were prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization.After removal the core templates of the poly(styrene),the hollow silica spheres were obtained.The coating process of poly(methyl methacrylate)(PMMA) on the hollow silica spheres surface via surface RAFT polymerization was performed subsequently.The polymers coated on the hollow spheres surfaces were end-functionalized by trithiocarbonate,and they were used as RAFT agent to proceed the chain extension polymerization using Tb complex as monomer.The samples were characterized by FT-IR,SEM and luminescence spectroscopy respectively.The results indicated that the triple-shelled hollow spheres had been prepared successfully and the average diameter of the hollow core was about 1μm.
基金financially supported by the National Natural Science Foundation of China (No.20873046)the Specialized Research Fund for the Doctoral Program of HigherEducation (No.200805740004)Natural Science Foundation of Guangdong Province (No.10351063101000001)
文摘TiO2-coated SnO2 (TCS) hollow spheres, which are new anode materials for lithium ion (Li-ion) batteries, were prepared and characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), cyclic voltammetry (CV), and galvanostatic charge/discharge tests. The results obtained from XRD, SEM, and TEM show that TiO2 can be uniforrrdy coated on the surface of SnO2 hollow spheres with the assistance of anionic surfactant. The cyclic voltammograms indicate that both TiO2 and SnO2 exhibit the activity for Li-ion storage. The charge/discharge tests show that the prepared TCS hollow spheres have a higher reversible coulomb efficiency and a better cycling stability than the uncoated SnO2 hollow spheres.
文摘Abstract: We performed fluidized bed coating ofAl-based nanoeomposite powder-binder suspensions onto polymer substrates. The effects of the type and amount of the binder and nanoparticle additive on the coating process efficiency and coating characteristics were investigated. The efficiency decreased from 52% to 49% as the processing time increased from 15 to 20 min. However, the amount and thickness of the coating also increased as the processing time and amount of the binder were increased. The addition of nanoparticles to the system decreased the thickness of the coating from 222 to 207 μm when polyvinyl alcohol (PVA) was used as a binder. The suspension containing 3wt% R-4410 binder exhibited the greatest efficiency of 60%.
基金supported by the Scholarship from China Scholarship Council(CSC)(Grant no.201604910621)。
文摘Catalyst support is extremely important for future fuel cell devices.In this work,we developed doubleshelled C/TiO2(DSCT)hollow spheres as an excellent catalyst support via a template-directed method.The combination of hollow structure,TiO2 shell and carbon layer results in excellent electron conductivity,electrocatalytic activity,and chemical stability.These uniformed DSCT hollow spheres are used as catalyst support to synthesize Pt/DSCT hollow spheres electrocatalyst.The resulting Pt/DSCT hollow spheres exhibited high catalytic performance with a current density of 462 mA mg^-1 for methanol oxidation reaction,which is 2.52 times higher than that of the commercial Pt/C.Furthermore,the increased tolerance to carbonaceous poisoning with a higher If/Ibratio and a better long-term stability in acid media suggests that the DSCT hollow sphere is a promising C/TiO2-based catalyst support for direct methanol fuel cells applications.
基金sponsored by the National Natural Science Foundation of China (No. 20171001)Natural Science Foundation of Anhui Provincial Department of Education (No. 2005KJ369ZC)
文摘CaCO3 hollow spheres were prepared easily in anion surfactants (sodium dodecylbenzenesulfonate (SDBS)) and aspartic (Asp) acid binary-additive system by using an easy rapid agitation method. The as-prepared products were characterized with scanning electron microscopy (SEM), FT-IR and X-ray diffraction. The results suggested that the CaCO3 hollow spheres have diameters ranging from 1 to 2 μm, and their wall is constituted of many nano-particles. Moreover, the possible formation mechanism of the hollow spherical structure was proposed.
文摘The controlled synthesis of ZnO hollow spheres is successfully achieved through a facile solvothermal method using a Keggin-type silicotungstic acid(H_4 Si(W_3 O_(10))_4:HSW) as structure directing agent. The formation process of these hollow spheres is proposed based on a variety of controlled experiments. In addition, Au nanoparticles are loaded onto the surface of ZnO hollow spheres. It is found that the Au-loaded ZnO(Au/ZnO) composites exhibit greatly enhanced activity on oxidizing Rhodamine B(Rh B) under simulated UV or visible light irradiation, compared to the pristine ZnO hollow spheres. The improved performance of Au/ZnO heterostructures is mainly attributed to the enhanced optical absorption and the accelerated separation and migration of photogenerated charge carriers. Moreover, the photocatalytic reaction mechanisms are proposed based on the results of electron spin resonance(ESR) analysis, photoelectrochemical measurements, and photocatalytic evaluation. The results and findings are expected to provide significance to the synthesis of noble metal-semiconductor hybrids towards water purification.
基金the National Natural Sciences Foundation of China(No.19872060)
文摘The free vibration of a functionally graded material hollow spheresubmerged in a compress- ible fluid medium is exactly analyzed. Thesphere is assumed to be spherically isotropic with material consta-nts being inhomogeneous along the radial direction. By employing aseparation technique as well as the spherical harmonics expansionmethod, the governing equations are simplified to an uncoupledsecond-order ordinary differential equation, and a coupled system oftwo such equations. Solutions to these equations are given when theelastic constants and the mass density are power functions of theradial coordinate. Numerical examples are finally given to show theeffect of the material gradient on the natural frequencies.
基金Supported by the "973" Basic Research Foundation of China(No.2006CB932605)the National Natural Science Founda-tion of China(No.20876002).
文摘Monoclinic Cu3V2O7(OH)2·2H2O(copper polyvanadate) hollow spheres were prepared with Na2V6O16·3H2O nanobelts as V-precursor by hydrothermal method. The purity and structure of the products were characterized by X-ray powder diffraction(XRD), Fourier transform infrared(FTIR) spectroscopy, Raman spectroscopy, thermogravimetric analysis(TGA) and X-ray photoelecton spectroscopy(XPS). The morphology and size were observed by scanning electron microscopy(SEM). We found that the Kagomé staircase-structural copper polyvanadate hollow spheres with an average diameter of 7 μm could be easily synthesized via the reaction of Na2V6O16·3H2O nanobelts with sufficient copper sulfate. The dielectric property of the copper polyvanadate demonstrates that dielectric loss hardly changes when the frequency of applied electric field is higher than 100 kHz. The formation process of the hollow spheres is discussed in detail by the observation of a series of products prepared for different reaction time.
文摘The effect of magnetic field on the plane vibrations for an elastodynamic orthotropic sphere is studied. Equations of elastodynamic problems of the orthotropic hollow sphere in terms of displacement are solved. The numerical results of the frequency equations in the presence of magnetic field are discussed and shown graphically. Compar-isons are made with the result in the presence and absence of magnetic field in the case of orthotropic sphere. The results show that the effect of magnetic field is very pronounced.
文摘INCO-617 alloy hollow sphere foams with average aperture of about 3 mm and about 0.12 mm wall thickness were fabricated by hollow sphere method.Firstly the wet spheres,which are formed as powder shells from slurry by coating polystyrene balls,were arranged with body-centered cubic(BCC) structure.Subsequently,the sphere stacks were heat-treated in vacuum at 350 ℃ for 40 min to decompose the organic materials,and sintered at different temperatures for different time.The effects of slurry components,sintering temperature and sintering time on the density and porosity of cell wall of hollow sphere foam were studied through Scanning Electron Microscopy.The results show that the densities of INCO-617 alloy hollow sphere foam,increasing with the increase of powder content in slurry,sintering temperature and sintering time,range from 1.112 to 1.216 g·cm-3.Extension of sintering time can reduce the porosity of cell wall,which enhances the compression strength of hollow sphere foam significantly.
基金This work was supported by the National Natural Science Foundation of China.
文摘Nanocrystalline MoS2 with hollow spherical morphology has been prepared by the hydrothermal method. The products are characterized by means of X-ray powder diffraction, transmission electron microscopy and high-resolution transmission electron microscopy. The experimental results give the evidence that the sample is consists of hollow spheres 400~600 nm in diameter, and there is much whisker on the surface of MoS2 hollow sphere.
基金financially supported by the National Natural Science Foundation of China (Nos. 21722604, 21878133, and22002050)China Postdoctoral Science Foundation (No.2020M671365)Postgraduate Research&Practice Innovation Program of Jiangsu Province (No. KYCX20_3039)。
文摘A series of basic nitrogen doped carbon hollow spheres(p-N-C) catalysts derived from waste tires were prepared by a green, facile and environmental “leavening” strategy for the catalytic oxidation of pentanethiol. Compared to pristine carbon, the p-N-C has a higher surface curvature conducive to the enrichment of substrates, leading to an excellent catalytic performance. This increased surface curvature of p-N-C was fabricated on the synergistic effect of two foaming agents((NH4)2 C2 O4 and NaHCO3), and the released gas also endows the spherical shell of p-N-C with a hierarchical porous structure, promoting the accessibility of active sites with pentanethiol. Pyridine-like and pyrrolic-like nitrogen atoms were investigated as reactive sites on the p-N-C to accelerate the electron transfer from sulfur to active surface oxygen and enhance the adsorption/oxidation process. As a result, the optimal p-N-C catalyst exhibits superior adsorption and oxidation performance(99.9%) of pentanethiol, outperforming the “unleavened”catalyst(20.8%). This work offers a new avenue for the fabrication of highly efficient materials for the desulfurization of fuel.
文摘Thermoelastic properties of hollow sphere composites are studied based on the uniform matrix-field concept proposed here. Some connections between local thermal and mechanical fields produced by certain homogeneous boundary conditions are derived, and furthermore, exact relations are also obtained between the effective thermoelastic properties of the composites. For a macroscopically isotropic composite with a certain ratio of the outer radius to the inner radius, it is found that the effective bulk modulus and the linear coefficient of thermal expansion can be exactly determined, if the thermal expansion coefficient of the matrix and that of the sphere are the same.
文摘Zirconia hollow sphere products are ultra-high temperature energy saving lightweight insulating refractories in zirconia system.They not only have the same refractoriness as zirconia products,but also have the advantages of low bulk density and excellent thermal insulation properties.Their thermal conductivity is 0.3-0.4 W · m-1 · K-1 only 1/2 of that of the ordinary zirconia products.They are special refractories which can be used steadily up to 2 400 ℃ in oxidation,reduction and vacuum atmospheres.Zirconia hollow sphere products are the best lining refractories for various ultra-high temperature kilns and furnaces of tungsten and molybdenum metal products processing,artificial crystals,and quartz industrial production.
基金financially supported by Shenzhen Fundamental Research Program(JCYJ20190809114409397)
文摘The unsatisfactory conductivity and large volume variation severely handicap the application of SnO_(2)in sodium-ion batteries(SIBs).Herein,we design unique three-layer structured SnO_(2)@C@TiO_(2)hollow spheres to tackle the above-mentioned issues.The hollow cavity affords empty space to accommodate the volume variation of SnO_(2),while the C and TiO_(2)protecting shells strengthen the structural integrity and enhances the electrical conductivity.As a result,the three-layer structured SnO_(2)@C@TiO_(2)hollow spheres demonstrate enhanced Na storage performances.The SnO_(2)@C@TiO_(2)manifests a reversible capacity two times to that of pristine SnO_(2)hollow spheres.In addition,Ex situ XRD reveals highly reversible alloying and conversion reactions in SnO_(2)@C@TiO_(2)hollow spheres.This study suggests the introduction of a hollow cavity and robust protecting shells is a promising strategy for constructing SIB anode materials.
文摘β-SiAION hollow spheres were prepared by carbothermal reduction method, using coal fly ash ( 〈 15 μm, 43 - 77 μm, and 〉 100 μm) and active carbon in Some proportion (20% less than theoretical addition, theoretical addition and 10% excess theoretical addition) as starting materials, putting into alumina crucible in high temperature nitriding furnace after well mixed, and holding at 1 300 ℃, 1 350 ℃, 1 400 ℃, 1 450 ℃, and 1 500 ℃ for 6 h. Effects of temperature, particle size of the microsphere . and addition of active carbon on the phase composition and microstructure of the nitridized products were studied by means of XRD and SEM. The results show that the nitridation reaction starts at 1 300 ℃ ; excess active carbon is necessary to form β-SiAION hollow spheres, and particle size is the important parameter to form the hollow spheres nitridized products β-SiAION; at 1 500 ℃, when the active carbon is 10% in excess, the β-SiAlON hollow spheres, which were prepared using coal fly ash with particle size 〉 100 μm, are featured with rough surface, high hollowness and low density.
基金the support provided by the National High Technology Research and Development Program 863 (No.2006AA05Z417)Science and Technology Platform Construction Project of Dalian (2010-354)+4 种基金the Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning (No.2013-70)‘‘Shu Guang’’ project supported by Shanghai Municipal Education Commission and Shanghai Education Development Foundation (No.13SG55)National Natural Science Foundation of China (NSFC) (No.61376009)Science and Technology Commission of Shanghai Municipality (No.14YF1410500)Shanghai Young Teacher Supporting Foundation (No.ZZEGD14011)
文摘A bi-layer photoanode for dye-sensitized solar cell(DSSC) was fabricated, in which TiO_2 hollow spheres(THSs) were designed as a scattering layer and P25/multi-walled carbon nanotubes(MWNTs) as an under-layer. The THSs were synthesized by a sacrifice template method and showed good light scattering ability as an over-layer of the photoanode. MWNTs were mixed with P25 to form an under-layer of the photoanode to improve the electron transmission ability of the photoanode. The power conversion efficiency of this kind of DSSC with bi-layer was enhanced to 5.13 %,which is 14.25 % higher than that of pure P25 DSSC.Graphical Abstract A bi-layer composite photoanode based on P25/MWNTs-THSs with improved light scattering and electron transmission, which will provide a new insight into fabrication and structure design of highly efficient dyesensitized solar cells.
文摘The separation of variables method was successfully used to resolve the spherically symmetric dynamic thermoelastie problem for a spherically isotropic elastic hollow sphere. Use of the integral transform can be avoided by means of this method, which is also appropriate for an arbitrary thickness hollow sphere subjected to arbitrary thermal and mechanical loads. Numerical results are presented to show the dynamic stress responses in the uniformly heated hollow spheres.