In this study, we have established a facile method to synthesize functional hollow carbon spheres with large hollow interior, which can act as active colloidal catalysts. The method includes the following steps： firs...In this study, we have established a facile method to synthesize functional hollow carbon spheres with large hollow interior, which can act as active colloidal catalysts. The method includes the following steps： first, hollow polymer spheres with large hollow interior were prepared using sodium oleate as the hollow core generator, and 2,4-dihydroxybenzoic acid and hexamethylene tetramine （HMT） as the polymer precursors under hydrothermal conditions; Fe3＋ or Ag＋ cations were then introduced into the as-prepared hollow polymer spheres through the carboxyl groups; finally, the hollow polymer spheres can be pseudomorphically converted to hollow carbon spheres during pyrolysis process, meanwhile iron or silver nanoparticles can also be formed in the carbon shell simultaneously. The structures of the obtained functional hollow carbon spheres were characterized by TEM, XRD, and TG. As an example, Ag-doped hollow carbon spheres were used as colloid catalysts which showed high catalytic activity in 4-nitrophenol reduction reaction.展开更多
A surfactant-assisted method for preparing colloidal spheres with narrow size distribution from a polydispersed azo polymer has been developed in this work. The colloidal spheres were formed through gradual hydrophobi...A surfactant-assisted method for preparing colloidal spheres with narrow size distribution from a polydispersed azo polymer has been developed in this work. The colloidal spheres were formed through gradual hydrophobic aggregation of the polymeric chains in THF-H2O dispersion media, which was induced by a steady increase in the water content. Results showed that the addition of a small amount of surfactant （SDBS） could significantly narrow the size distribution of the colloidal spheres. The size distribution of the colloidal spheres was determined by the concentrations of azo polymer and the amount of surfactant in the systems. When the concentrations of polymer and surfactant amount were in a proper range, colloidal spheres with narrow size distribution could be obtained. The colloidal spheres formed by this method could be elongated along the polarization direction of the laser beams to be a new type of the colloid-based functional materials. upon Ar^＋ laser irradiation. The colloidal spheres are considered展开更多
A versatile and reliable approach is created to fabricate wafer-scale colloidal crystal that consists of a monolayer of hexagonally close-packed polystyrene （PS） spheres. Making wafer-scale colloidal crystal is usua...A versatile and reliable approach is created to fabricate wafer-scale colloidal crystal that consists of a monolayer of hexagonally close-packed polystyrene （PS） spheres. Making wafer-scale colloidal crystal is usually challenging, and it lacks a general theoretical guidance for experimental approaches. To obtain the optimal conditions for self-assembly, a systematic statistical design and analysis method is utilized here, which applies the pick-the-winner rule. This new method combines spin-coating and thermal treatment, and introduces a mixture of glycol and ethanol as a dispersion system to assist self-assembly. By controlling the parameters of self-assembly, we improve the quality of colloidal crystal and reduce the effect of noise on the experiment. To our best knowledge, we are first to pave this path to harvest colloidal crystals. Importantly, a theoretical analysis using an energy landscape base on our process is also developed to provide insights into the PS spheres＇ self-assembly.展开更多
We investigate the transport properties and mechanical response of glassy hard disks using nonlinear Langevin equation theory.We derive expressions for the elastic shear modulus and viscosity in two dimensions on the ...We investigate the transport properties and mechanical response of glassy hard disks using nonlinear Langevin equation theory.We derive expressions for the elastic shear modulus and viscosity in two dimensions on the basis of thermalactivated barrier-hopping dynamics and mechanically accelerated motion.Dense hard disks exhibit phenomena such as softening elasticity,shear-thinning of viscosity,and yielding upon deformation,which are qualitatively similar to dense hard-sphere colloidal suspensions in three dimensions.These phenomena can be ascribed to stress-induced ＂landscape tilting＂.Quantitative comparisons of these phenomena between hard disks and hard spheres are presented.Interestingly,we find that the density dependence of yield stress in hard disks is much more significant than in hard spheres.Our work provides a foundation for further generalizing the nonlinear Langevin equation theory to address slow dynamics and rheological behavior in binary or polydisperse mixtures of hard or soft disks.展开更多
Monodisperse polystyrene (PS) colloidal spheres were successfully prepared through emulsifier-free emulsion polymerization by controlling the polymerization reaction time, ionic strength of the system, concentration o...Monodisperse polystyrene (PS) colloidal spheres were successfully prepared through emulsifier-free emulsion polymerization by controlling the polymerization reaction time, ionic strength of the system, concentration of the ionic copolymer (sodium p-styrenesulfonate) and other factors. The PS colloidal spheres were assembled into colloidal crystals whose structures were mainly face-centered cubic (fcc) close-packed. Then FDTD method was used to calculate the color-rendering characteristics of the colloidal crystals surface. The calculated results were consistent with the experimental results.展开更多
SiO2 colloidal spheres were synthesized by St-ber method. In order to enhance surface charge of the SiO2 spheres, they were modified with succinic acid. Scanning electron microscope (SEM) shows that the average size o...SiO2 colloidal spheres were synthesized by St-ber method. In order to enhance surface charge of the SiO2 spheres, they were modified with succinic acid. Scanning electron microscope (SEM) shows that the average size of modified SiO2 spheres is 473 nm, and its distribution standard deviation is less than 5%; Fourier-transform infrared spectra (FT-IR) and X-ray photoelectron spectrometer (XPS) results indicate that one end of succinic acid is chemically bonded to the SiO2 spheres through esterification; Zeta potential of the modified SiO2 spheres in water solution is improved from -53.72 to -67.46 mV, and surface charge density of the modified SiO2 spheres is enhanced from 0.19 to 0.94 μC/cm2. SiO2 colloidal crystal was fabricated from aqueous colloidal solution by the vertical deposition method at 40℃ and 60% relative humidity. SEM images show that the sample of SiO2 colloidal crystal is face-centered cubic (fcc) structure with its (111) planes parallel to the substrate. Transmission measurement shows the existence of photonic band gap at 1047 nm.展开更多
Uniform CdS colloidal spheres have been successfully synthesized via a simple hydrothermal method. X-ray diffraction （XRD） analyses indicate that the products exhibit a hexagonal structure. Scanning electron （SEM）...Uniform CdS colloidal spheres have been successfully synthesized via a simple hydrothermal method. X-ray diffraction （XRD） analyses indicate that the products exhibit a hexagonal structure. Scanning electron （SEM） and transmission electron microscopy （TEM） are used to characterize CdS colloidal spheres. The final size of the spheres may be selected from a range of 71± 2 nm to approximately 181 ± 5 nm by changing the amount of polyvinylpyrrolidone （PVP） and hexamethylenetetramine （HMT）. The CdS colloidal spheres are not obtained in the absence of either of the capping agents. A synergistic effect between HMT and PVP is proposed to be crucial for the formation of colloidal spheres.展开更多
Selective hydrogenation of the carbonyl bond inα,β-unsaturated carbonyl compounds is rather challenging owing to the more feasible hydrogenation of ethylenic bond from both thermodynamic and kinetic aspects.Here,we ...Selective hydrogenation of the carbonyl bond inα,β-unsaturated carbonyl compounds is rather challenging owing to the more feasible hydrogenation of ethylenic bond from both thermodynamic and kinetic aspects.Here,we demonstrate a facile emulsionbased molecule-nanoparticle self-assembly strategy for the atomic engineering of Ir species on three-dimensional CeO_(2)spheres(Ir1@CeO_(2)).When applied to the hydrogenation ofα,β-unsaturated aldehydes,Ir1@CeO_(2)catalyst remarkably exhibited~100%selectivity towards unsaturated alcohols,whereas the formation of Ir nanoparticles on CeO_(2)drastically decreased the selectivity for unsaturated alcohols.Spectroscopic studies revealed that strong metal-support interactions triggered the charge transfer from Ir to CeO_(2),leading to the partial reduction of Ce^(4+)to Ce^(3+)along with the formation new Ir^(δ+)-O_(2)--Ce^(3+)(OV)interfaces.The electrophilic atomic Ir species at the Ir^(δ+)-O_(2)--Ce^(3+)(OV)interfaces would therefore preferentially adsorb and facilitate hydrogenation of polar C=O bond to achieve exceptional selectivity.展开更多
A highly stretchable plasmonic structure composed of a monolayer array of metal-capped colloidal spheres on an elastomeric substrate has been fabricated using simple and inexpensive self-assembly and transfer-printing...A highly stretchable plasmonic structure composed of a monolayer array of metal-capped colloidal spheres on an elastomeric substrate has been fabricated using simple and inexpensive self-assembly and transfer-printing techniques.This composite structure supports coupled surface plasmons whose wavelengths are sensitive to the arrangement of the metal-capped colloidal spheres.Upon stretching,the lattice of metal-capped colloidal spheres will be deformed,leading to a large wavelength shift of surface plasmon resonances and simultaneously an obvious color change.This stretchable plasmonic structure offers a promising approach to tune surface plasmon resonances and might be exploited in realizing flexible plasmonic devices with tunability of mechanical strain.展开更多
An enhanced KR-fundamental measure functional （FMF） is elaborated and employed to investigate binary and ternary hard sphere fluids near a planar hard wall or confined within two planar hard walls separated by certa...An enhanced KR-fundamental measure functional （FMF） is elaborated and employed to investigate binary and ternary hard sphere fluids near a planar hard wall or confined within two planar hard walls separated by certain interval. The present enhanced KR-FMF incorporates respectively, for aim of comparison, a recent 3rd-order expansion equation of state （EOS） and a Boublfk＇s extension of Kolafa＇s EOS for HS mixtures. It is indicated that the two versions of the EOS lead to, in the framework of the enhanced KR-FMF, similar density profiles, but the 3rd-order EOS is more consistent with an exact scaled particle theory （SPT） relation than the BK EOS. Extensive comparison between the enhanced KR-FMF-3rd-order EOS predictions and corresponding density profiles produced in different periods indicates the excellent performance of the present enhanced KR-FMF-3rd-order EOS in comparison with other available density functional approximations （DFAs）. There are two anomalous situations from whose density profiles all DFAs studied deviate significantly; however, subsequent new computer simulation results for state conditions similar to the two anomalous situations are in very excellent agreement with the present enhanced KR-FMF-3rd-order EOS. The present paper indicates that （i） the validity of the ＂naive＂ substitution elaborated in the present paper and peculiar to the original KR-FMF is still in operation even if inhomogeneoas mixtures are being dealt with; （ii） the high accuracy and self-consistency of the third order EOS seem to allow for application of the KR-FMF-third order EOS to more severe state conditions; and （iii） the ＂naive＂ substitution enables very easy the combination of the original KR-FMF with future＇s more accurate but potentially more complicated EOS of hard sphere mixtures.展开更多
A novel copper-mediated solvothermal method was proposed for synthesizing colloidal spheres of a new composition, palladium iodide （PdI2）. Typical procedure was designed to involve the introduction of cupric chlori...A novel copper-mediated solvothermal method was proposed for synthesizing colloidal spheres of a new composition, palladium iodide （PdI2）. Typical procedure was designed to involve the introduction of cupric chloride （CuCI2） as weak oxidant. CuCI2 was found to be essential for preventing the easy formation of palladium deposits as well as facilitating the synthesis and assembly. Under the co-effect of CuC12 and the surfactant of polyvinylpyrrolidone （PVP）, neutral PdI2 colloidal spheres with narrow size distribution were successfully produced. Such ion-assisted synthetic method is believed to be prospective in producing well-constructed nanostructures.展开更多
Colloidal carbon spheres with hydrophilic surface were synthesized using glucose as precursor by hydrothermal methods.Amorphous SiO2,anatase TiO2 and cassiterite SnO2 hollow spheres were successfully prepared using co...Colloidal carbon spheres with hydrophilic surface were synthesized using glucose as precursor by hydrothermal methods.Amorphous SiO2,anatase TiO2 and cassiterite SnO2 hollow spheres were successfully prepared using colloidal carbon spheres as template in conjunciton with the sol-gel method.The hollow spherical structures could be confirmed by TEM and SEM.The BET surface area of hollow spheres were about 183.8 m2/g,32.5m2/g,and 74.3m2/g,respectively.展开更多
基金supported by NSFC (No. 20873014 and 21073026)the Program for New Century Excellent Talents in University of China (NCET-09-0254)
文摘In this study, we have established a facile method to synthesize functional hollow carbon spheres with large hollow interior, which can act as active colloidal catalysts. The method includes the following steps： first, hollow polymer spheres with large hollow interior were prepared using sodium oleate as the hollow core generator, and 2,4-dihydroxybenzoic acid and hexamethylene tetramine （HMT） as the polymer precursors under hydrothermal conditions; Fe3＋ or Ag＋ cations were then introduced into the as-prepared hollow polymer spheres through the carboxyl groups; finally, the hollow polymer spheres can be pseudomorphically converted to hollow carbon spheres during pyrolysis process, meanwhile iron or silver nanoparticles can also be formed in the carbon shell simultaneously. The structures of the obtained functional hollow carbon spheres were characterized by TEM, XRD, and TG. As an example, Ag-doped hollow carbon spheres were used as colloid catalysts which showed high catalytic activity in 4-nitrophenol reduction reaction.
基金The financial support by the NSFC under Projects (Nos. 50533040, 20374033) is gratefully acknowledged.
文摘A surfactant-assisted method for preparing colloidal spheres with narrow size distribution from a polydispersed azo polymer has been developed in this work. The colloidal spheres were formed through gradual hydrophobic aggregation of the polymeric chains in THF-H2O dispersion media, which was induced by a steady increase in the water content. Results showed that the addition of a small amount of surfactant （SDBS） could significantly narrow the size distribution of the colloidal spheres. The size distribution of the colloidal spheres was determined by the concentrations of azo polymer and the amount of surfactant in the systems. When the concentrations of polymer and surfactant amount were in a proper range, colloidal spheres with narrow size distribution could be obtained. The colloidal spheres formed by this method could be elongated along the polarization direction of the laser beams to be a new type of the colloid-based functional materials. upon Ar^＋ laser irradiation. The colloidal spheres are considered
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11504264,51501128,and 61274064)
文摘A versatile and reliable approach is created to fabricate wafer-scale colloidal crystal that consists of a monolayer of hexagonally close-packed polystyrene （PS） spheres. Making wafer-scale colloidal crystal is usually challenging, and it lacks a general theoretical guidance for experimental approaches. To obtain the optimal conditions for self-assembly, a systematic statistical design and analysis method is utilized here, which applies the pick-the-winner rule. This new method combines spin-coating and thermal treatment, and introduces a mixture of glycol and ethanol as a dispersion system to assist self-assembly. By controlling the parameters of self-assembly, we improve the quality of colloidal crystal and reduce the effect of noise on the experiment. To our best knowledge, we are first to pave this path to harvest colloidal crystals. Importantly, a theoretical analysis using an energy landscape base on our process is also developed to provide insights into the PS spheres＇ self-assembly.
基金Project supported by the National Basic Research Program of China(Grant No.2012CB821500)the National Natural Science Foundation of China(Grant Nos.21374073 and 21574096)
文摘We investigate the transport properties and mechanical response of glassy hard disks using nonlinear Langevin equation theory.We derive expressions for the elastic shear modulus and viscosity in two dimensions on the basis of thermalactivated barrier-hopping dynamics and mechanically accelerated motion.Dense hard disks exhibit phenomena such as softening elasticity,shear-thinning of viscosity,and yielding upon deformation,which are qualitatively similar to dense hard-sphere colloidal suspensions in three dimensions.These phenomena can be ascribed to stress-induced ＂landscape tilting＂.Quantitative comparisons of these phenomena between hard disks and hard spheres are presented.Interestingly,we find that the density dependence of yield stress in hard disks is much more significant than in hard spheres.Our work provides a foundation for further generalizing the nonlinear Langevin equation theory to address slow dynamics and rheological behavior in binary or polydisperse mixtures of hard or soft disks.
文摘Monodisperse polystyrene (PS) colloidal spheres were successfully prepared through emulsifier-free emulsion polymerization by controlling the polymerization reaction time, ionic strength of the system, concentration of the ionic copolymer (sodium p-styrenesulfonate) and other factors. The PS colloidal spheres were assembled into colloidal crystals whose structures were mainly face-centered cubic (fcc) close-packed. Then FDTD method was used to calculate the color-rendering characteristics of the colloidal crystals surface. The calculated results were consistent with the experimental results.
基金Supported by the National Natural Science Foundation of China (Grant No. 50372038)
文摘SiO2 colloidal spheres were synthesized by St-ber method. In order to enhance surface charge of the SiO2 spheres, they were modified with succinic acid. Scanning electron microscope (SEM) shows that the average size of modified SiO2 spheres is 473 nm, and its distribution standard deviation is less than 5%; Fourier-transform infrared spectra (FT-IR) and X-ray photoelectron spectrometer (XPS) results indicate that one end of succinic acid is chemically bonded to the SiO2 spheres through esterification; Zeta potential of the modified SiO2 spheres in water solution is improved from -53.72 to -67.46 mV, and surface charge density of the modified SiO2 spheres is enhanced from 0.19 to 0.94 μC/cm2. SiO2 colloidal crystal was fabricated from aqueous colloidal solution by the vertical deposition method at 40℃ and 60% relative humidity. SEM images show that the sample of SiO2 colloidal crystal is face-centered cubic (fcc) structure with its (111) planes parallel to the substrate. Transmission measurement shows the existence of photonic band gap at 1047 nm.
基金supported by the National Natural Science Foundation of China(Nos.50972080 and 91127017)the National Basic Research Program(No.2009CB930101)the Key Laboratory of Photochemical Conversion and Optoelectronic Materials,TIPC,CAS
文摘Uniform CdS colloidal spheres have been successfully synthesized via a simple hydrothermal method. X-ray diffraction （XRD） analyses indicate that the products exhibit a hexagonal structure. Scanning electron （SEM） and transmission electron microscopy （TEM） are used to characterize CdS colloidal spheres. The final size of the spheres may be selected from a range of 71± 2 nm to approximately 181 ± 5 nm by changing the amount of polyvinylpyrrolidone （PVP） and hexamethylenetetramine （HMT）. The CdS colloidal spheres are not obtained in the absence of either of the capping agents. A synergistic effect between HMT and PVP is proposed to be crucial for the formation of colloidal spheres.
基金the National Natural Science Foundation of China(No.21901007)the Natural Science Foundation of Anhui Province(No.2008085QB83)+1 种基金the Science and Technology Development Fund(FDCT)of Macao SAR(No.0032/2021/ITP)the University of Macao(No.MYRG2020-00026-FST)。
文摘Selective hydrogenation of the carbonyl bond inα,β-unsaturated carbonyl compounds is rather challenging owing to the more feasible hydrogenation of ethylenic bond from both thermodynamic and kinetic aspects.Here,we demonstrate a facile emulsionbased molecule-nanoparticle self-assembly strategy for the atomic engineering of Ir species on three-dimensional CeO_(2)spheres(Ir1@CeO_(2)).When applied to the hydrogenation ofα,β-unsaturated aldehydes,Ir1@CeO_(2)catalyst remarkably exhibited~100%selectivity towards unsaturated alcohols,whereas the formation of Ir nanoparticles on CeO_(2)drastically decreased the selectivity for unsaturated alcohols.Spectroscopic studies revealed that strong metal-support interactions triggered the charge transfer from Ir to CeO_(2),leading to the partial reduction of Ce^(4+)to Ce^(3+)along with the formation new Ir^(δ+)-O_(2)--Ce^(3+)(OV)interfaces.The electrophilic atomic Ir species at the Ir^(δ+)-O_(2)--Ce^(3+)(OV)interfaces would therefore preferentially adsorb and facilitate hydrogenation of polar C=O bond to achieve exceptional selectivity.
基金This work was supported by the National Program on Key Basic Research Project(973 Program)(Grant Nos.2007CB613200 and 2006CB921700)The research of J.Z.and X.H.L.is further supported by the National Natural Science Foundation of China(NSFC)and the Shanghai Science and Technology Commission.
文摘A highly stretchable plasmonic structure composed of a monolayer array of metal-capped colloidal spheres on an elastomeric substrate has been fabricated using simple and inexpensive self-assembly and transfer-printing techniques.This composite structure supports coupled surface plasmons whose wavelengths are sensitive to the arrangement of the metal-capped colloidal spheres.Upon stretching,the lattice of metal-capped colloidal spheres will be deformed,leading to a large wavelength shift of surface plasmon resonances and simultaneously an obvious color change.This stretchable plasmonic structure offers a promising approach to tune surface plasmon resonances and might be exploited in realizing flexible plasmonic devices with tunability of mechanical strain.
基金Supported by the National Natural Science Foundation of China under Grant No.20973202
文摘An enhanced KR-fundamental measure functional （FMF） is elaborated and employed to investigate binary and ternary hard sphere fluids near a planar hard wall or confined within two planar hard walls separated by certain interval. The present enhanced KR-FMF incorporates respectively, for aim of comparison, a recent 3rd-order expansion equation of state （EOS） and a Boublfk＇s extension of Kolafa＇s EOS for HS mixtures. It is indicated that the two versions of the EOS lead to, in the framework of the enhanced KR-FMF, similar density profiles, but the 3rd-order EOS is more consistent with an exact scaled particle theory （SPT） relation than the BK EOS. Extensive comparison between the enhanced KR-FMF-3rd-order EOS predictions and corresponding density profiles produced in different periods indicates the excellent performance of the present enhanced KR-FMF-3rd-order EOS in comparison with other available density functional approximations （DFAs）. There are two anomalous situations from whose density profiles all DFAs studied deviate significantly; however, subsequent new computer simulation results for state conditions similar to the two anomalous situations are in very excellent agreement with the present enhanced KR-FMF-3rd-order EOS. The present paper indicates that （i） the validity of the ＂naive＂ substitution elaborated in the present paper and peculiar to the original KR-FMF is still in operation even if inhomogeneoas mixtures are being dealt with; （ii） the high accuracy and self-consistency of the third order EOS seem to allow for application of the KR-FMF-third order EOS to more severe state conditions; and （iii） the ＂naive＂ substitution enables very easy the combination of the original KR-FMF with future＇s more accurate but potentially more complicated EOS of hard sphere mixtures.
基金supported by the National Basic Program of China for Nanoscience and Nanotechnology (973 Program,2011CB932401)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China (20921001)
文摘A novel copper-mediated solvothermal method was proposed for synthesizing colloidal spheres of a new composition, palladium iodide （PdI2）. Typical procedure was designed to involve the introduction of cupric chloride （CuCI2） as weak oxidant. CuCI2 was found to be essential for preventing the easy formation of palladium deposits as well as facilitating the synthesis and assembly. Under the co-effect of CuC12 and the surfactant of polyvinylpyrrolidone （PVP）, neutral PdI2 colloidal spheres with narrow size distribution were successfully produced. Such ion-assisted synthetic method is believed to be prospective in producing well-constructed nanostructures.
文摘Colloidal carbon spheres with hydrophilic surface were synthesized using glucose as precursor by hydrothermal methods.Amorphous SiO2,anatase TiO2 and cassiterite SnO2 hollow spheres were successfully prepared using colloidal carbon spheres as template in conjunciton with the sol-gel method.The hollow spherical structures could be confirmed by TEM and SEM.The BET surface area of hollow spheres were about 183.8 m2/g,32.5m2/g,and 74.3m2/g,respectively.
