Cobalt selenide(CoSe_(2))anchored monodisperse Pt presents good acidic 2e^(-)oxygen reduction reaction(ORR)performance;however,conventional preparation methods can only yield ultra-low content of Pt atom catalysts.It ...Cobalt selenide(CoSe_(2))anchored monodisperse Pt presents good acidic 2e^(-)oxygen reduction reaction(ORR)performance;however,conventional preparation methods can only yield ultra-low content of Pt atom catalysts.It is necessary to design catalysts with a high loading of monodisperse Pt to improve the activity and selectivity.Here,we reported anchoring highly reactive Pt atoms by constructing surface Co vacancies on CoSe_(2)(Pt_(1)/md-CoSe_(2)),thereby increasing the co ntent of Pt atoms.The monodisperse Pt is not only a reactive active site but also helps to improve the intrinsic activity of Co around Pt with a suitable electronic structu re,which contributes to the simultaneous enhancement of~*O_(2) adsorption and lowering of the reaction activation energy,accelerating the 2e^(-)ORR kinetics.The Pt_1/md-CoSe_(2) with a 0.2 wt%Pt exhibits high performa nce of electrocatalytic acidic 2e^(-)ORR.The H_(2)O_(2) yield is 1160.2 mmol g_(cat)^(-1).h^(-1)with a Faraday efficiency(FE)of 95.2%(0 V vs.RHE)at 0.1 M HClO_(4),superior to most of the reported literature.Moreover,the catalyst did not deactivate after a stability test of 30 h at the high current density of 100 mA cm^(-2).This work provides guidance for designing catalysts with applications and understanding the action mechanism of monodisperse Pt atoms.展开更多
Monodisperse Ag nanoparticles with diameters of about 3.4 nm were synthesized by a facile ultrasonic synthetic route at room temperature with the reduction of borane-tert-butylamine in the presence of oleylamine （OAm...Monodisperse Ag nanoparticles with diameters of about 3.4 nm were synthesized by a facile ultrasonic synthetic route at room temperature with the reduction of borane-tert-butylamine in the presence of oleylamine （OAm） and oleic acid （OA）. The reaction parameters of time, the molar ratios of OAm to OA were studied, and it was found that these parameters played important roles in the morphology and size of the products. Meanwhile, surface enhanced Raman spectrum （SERS） property suggested the Ag nanoparticles exhibited high SERS effect on the model molecule Rhodamine 6G. And also, two-photon fluorescence images showed that the silver nanoparticles had high performances in fluorescence enhancement.展开更多
Monodisperse ZnxCd1-xS spheres were successfully fabricated with a high yield by a facile hydrothermal route.The as-prepared samples were characterized by X-ray diffractometry,scanning electron microscopy and UV-vis d...Monodisperse ZnxCd1-xS spheres were successfully fabricated with a high yield by a facile hydrothermal route.The as-prepared samples were characterized by X-ray diffractometry,scanning electron microscopy and UV-vis diffusion reflectance spectroscopy.The results indicate that all the prepared samples have the same hexagonal wurtzite phase and exhibit good size uniformity and regularity.Degradation of rhodamine-B（RhB） was used to evaluate the photocatalytic activities of ZnxCd1-xS samples.Zn0.4Cd0.6S possessed the best photocatalytic activity and exhibited high stability during the reaction.展开更多
Monodisperse spherical SiO2 particles were successfully synthesized in 2-propanol-H2O-NH3 system by the microwave hydrothermal method using ammonia as catalyst. To investigate the influences on the size of spherical S...Monodisperse spherical SiO2 particles were successfully synthesized in 2-propanol-H2O-NH3 system by the microwave hydrothermal method using ammonia as catalyst. To investigate the influences on the size of spherical SiO2 particles, factors such as ammonia concentration, reaction temperature, stirring intensity and reactants mol ratio have been studied. The orthogonal experiments were carried out. The as-prepared SiO2 particles were characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, Fourier transform infrared spectroscopy （FTIR） and differential thermal analysis （DTA）. The results indicated that the size of SiO2 particles increased greatly with the increase in ammonia concentration, temperature and reactants mol ratio, but increased slightly with the increase in stirring intensity. Monodisperse spherical Si02 particles were amorphous with perfect sphere and uniform size. Hydroxyl was detected in SiO2. Kinetic parameters were calculated, and finally the reaction rate equation of dehydrated hydroxyl was obtained.展开更多
In this work, we describe the one-pot synthesis of PEGylated mesoporous silica nanoparticles （MSNs） with uniform shape, tunable sizes, and narrow size distributions. The size of these nanoparticles can be controlled...In this work, we describe the one-pot synthesis of PEGylated mesoporous silica nanoparticles （MSNs） with uniform shape, tunable sizes, and narrow size distributions. The size of these nanoparticles can be controlled from 49 nm to 98 nm by simply varying the concentration oftriethanolamine during the base- catalyzed sol-gel reaction. Particles were characterized by transmission electron microscopy, dynamic light scattering, Fourier transform infrared spectrometry, thermogravimetric analysis, and nitrogen adsorption-desorption measurements. These PEGylated MSNs exhibited excellent long-term stability in biological media, which ensures their potential applications in drug delivery.展开更多
Monodisperse crosslinked poly(chloromethylstyrene-co-divinylbenzene)(poly(CMSt-co-DVB))microsphereswere prepared by distillation-precipitation copolymerization of chloromethylstyrene(CMSt)and divinylbenzene(DVB)inneat...Monodisperse crosslinked poly(chloromethylstyrene-co-divinylbenzene)(poly(CMSt-co-DVB))microsphereswere prepared by distillation-precipitation copolymerization of chloromethylstyrene(CMSt)and divinylbenzene(DVB)inneat acetonitrile.The polymer particles had clean surfaces due to the absence of any added stabilizer.The size of the particlesranges from 2.59 μm to 3.19 μm and with mono-dispersity around 1.002-1.014.The effects of monomer feed incopolymerization on the microsphere formation were described.The polymer microspheres were characterized by SEM andchlorinity elemental analysis.展开更多
Monodisperse titania glycolate submicrospheres were synthesized by a modified sol-gel route, in which ultrasonic treatment was introduced to improve the reaction efficiency. The as-prepared products were characterized...Monodisperse titania glycolate submicrospheres were synthesized by a modified sol-gel route, in which ultrasonic treatment was introduced to improve the reaction efficiency. The as-prepared products were characterized by means of Fourier transform infrared spectrum （FT-IR）, transmission electron microscopy （TEM）, powder X-ray diffraction （XRD）, and scanning electron microscopy （SEM）. The results indicate that the as-prepared products are titania glycolate submicrospheres with diameters of 230-330 nm. The average particle diameter is estimated to be about 280 nm. Ultrasonic treatment has an important influence on the morphology of the produced titania glycolates. After calcination at 450°C for 2 h, these titania glycolates were completely converted into anatase TiO2. The morphology of TiO2 particles was well reserved during the calcination process except for a reduction of 18% in the average particle size.展开更多
Abstract： Uniform Er3A15O12 spheres are of great value for fabricating optical ceramics. The highly monodisperse and size-controllable erbium aluminum garnet （EAG） precursors for transparent ceramics were successfu...Abstract： Uniform Er3A15O12 spheres are of great value for fabricating optical ceramics. The highly monodisperse and size-controllable erbium aluminum garnet （EAG） precursors for transparent ceramics were successfully synthesized through a new microwave process. The precursors constituted of ultrafine particles joining together by a hydroxyls formed compact network structure in the absence of SO42 , however, the morphologies of the precursors exhibited spheres with trace amount of SO42-. With manipulated programming of microwave irradiation parameters, narrow distributed particles of 40-50 nm were finally obtained by a separation of nu- cleation and nanocrystal growth. The mechanism behind the influence of microwave irradiation parameters on the growth of EAG precursors was preliminarily analysed. Easily dispersible and pure phase EAG were obtained at 950℃. The as-prepared EAG powders were used to fabricate transparent ceramics and transparent polycrystalline EAG ceramics were obtained under hydrogen furnace at 1750℃ for 8 h.展开更多
Magnetite （Fe3O4） nanoparticles with different sizes and shapes are synthesized by the thermal decomposition method. Two approaches, non-injection one-pot and hot-injection methods, are designed to investigate the g...Magnetite （Fe3O4） nanoparticles with different sizes and shapes are synthesized by the thermal decomposition method. Two approaches, non-injection one-pot and hot-injection methods, are designed to investigate the growth mechanism in detail. It is found that the size and shape of nanoparticles are determined by adjusting the precursor concentration and duration time, which can be well explained by the mechanism based on the LaMer model in our synthetic system. The monodisperse Fe3O4 nanoparticles have a mean diameter from 5nm to 16nm, and shape evolution from spherical to triangular and cubic. The magnetic properties are size-dependent, and Fe3O4 nanoparticles in small size about 5 nm exhibit superparamagnetie properties at room temperature and maximum saturation magnetization approaches to 78 emu/g, whereas Fe3O4 nanoparticles develop ferromagnetic properties when the diameter increases to about 16nm.展开更多
Simultaneous achievement in high solid content and high microsphere yield is deemed a challenge in the fabrication of monodisperse microspheres by precipitation polymerization.We herein demonstrate that micro-sized mo...Simultaneous achievement in high solid content and high microsphere yield is deemed a challenge in the fabrication of monodisperse microspheres by precipitation polymerization.We herein demonstrate that micro-sized monodisperse poly(methacrylic monomer-divinylbenzene)microspheres containing epoxy,lauyl,carboxyl and hydroxyl functions can be fabricated by solvothermal precipitation copolymerization at 20%(mass)monomer loading with over 94%microsphere yield.The morphology and porosity of the obtained particles can be readily tuned by cosolvent-acetonitrile binary solvents.Addition of a small amount of cosolvent that has similar solubility parameter to that of the functional monomer can significantly improve the monodispersity of the obtained microspheres.When tetrahydrofuran was used as the co-solvent,the surface area of the highly porous microspheres achieved higher than 400 m^(2)·g^(-1).Solvothermal precipitation co-polymerization can be expected in scale-up fabrication of various monodisperse functional microspheres free of any surfactant and additive.展开更多
The active sites of monodisperse transition metal Ni-clusters were anchored on carbon nitride(CN)by an in situ photoreduction deposition method to promote the efficient separation of photogenerated charges and achieve...The active sites of monodisperse transition metal Ni-clusters were anchored on carbon nitride(CN)by an in situ photoreduction deposition method to promote the efficient separation of photogenerated charges and achieve high-efficiency photocatalytic activity for hydrogen evolution.The Ni-cluster/CN exhibited a photocatalytic hydrogen production rate of 16.5 mmol·h^(-1)·g^(-1) and a total turnover frequency(TOF(H_(2)))value of 461.14 h^(-1).X-ray absorption spectroscopy based on synchrotron radiation indicated that CN had two reaction centers to form stable interface interactions with monodispersed Ni-clusters,in which carbon can act as an electron acceptor,while nitrogen can act as an electron donor.Meanwhile,the hybrid electronic structure of the Ni-cluster/CN system was constructed,which was favorable for photocatalytic activity for hydrogen production.An in-depth understanding of the interfacial interaction between CN and Ni-clusters will have important reference significance on the mechanistic study of development based on the cocatalyst.展开更多
Monodispersed microsized copper oxalate particles were prepared in a segmented continuous flow tube reactor, and the effect of the main parameters such as organic additive agent, initial copper ions concentration, res...Monodispersed microsized copper oxalate particles were prepared in a segmented continuous flow tube reactor, and the effect of the main parameters such as organic additive agent, initial copper ions concentration, residence time, and segmented media on the final products were investigated experimentally. The obtained copper oxalate microsized particles were disc-like in the presence of citrate ligand,which was the shape inducer for the precipitated copper oxalate. Thermodynamic equilibrium diagrams of the Cu(Ⅱ)-oxalate-H_2O,Cu(Ⅱ)-oxalate-citrate-H_2O, and Cu(Ⅱ)-oxalate-EDTA-H_2O solution systems were drawn to estimate the possible copper species under the experimental conditions and to explain the formation mechanisms of copper oxalate particles in the segmented fluidic reactor. Both theoretical and experimental results indicated that the presence of chelating reagents such as citrate and EDTA had distinct effect on the evolution of particle shape. Air and kerosene were tested as media for the fluidic flow segmentation, and the latter was verified to better promote the growth of copper oxalate particles. The present study provides an easy method to prepare monodispersed copper oxalate microsized particles in a continuous scaling-up way, which can be utilized to prepare the precursor material for conductive inks.展开更多
Lithium sulfur battery(LSB)is a promising energy storage system to meet the increasing energy demands for electric vehicles and smart grid,while its wide commercialization is severely inhibited by the"shuttle eff...Lithium sulfur battery(LSB)is a promising energy storage system to meet the increasing energy demands for electric vehicles and smart grid,while its wide commercialization is severely inhibited by the"shuttle effect"of polysulfides,low utilization of sulfur cathode,and safety of lithium anode.To overcome these issues,herein,monodisperse polar NiCo_(2)O_(4)nanoparticles decorated porous graphene aerogel composite(NCO-GA)is proposed.The aerogel composite demonstrates high conductivity,hierarchical porous structure,high chemisorption capacity and excellent electrocatalytic ability,which effectively inhibits the"shuttle effect",promotes the ion/electron transport and increases the reaction kinetics.The NCO-GA/S cathode exhibits high discharge specific capacity(1214.1 mAh g^(-1)at 0.1 C),outstanding rate capability(435.7 mAh g^(-1)at 5 C)and remarkable cycle stability(decay of 0.031%/cycle over 1000 cycles).Quantitative analyses show that the physical adsorption provided by GA mainly contributes to the capacity of NCO-GA/S at low rate,while the chemical adsorption provided by polar NiCo_(2)O_(4)contributes mainly to the capacity of NCO-GA/S with the increase of current density and cycling.This work provides a new strategy for the design of GA-based composite with synergistic adsorption and electrocatalytic activity for the potential applications in LSB and related energy fields.展开更多
Monodisperse crosslinked polystyrene （CPS） particles were prepared through the normal emulsion polymerization method by adding crosslinker--divinylbenzene （DVB） into the reaction system after polystyrene （PS） pa...Monodisperse crosslinked polystyrene （CPS） particles were prepared through the normal emulsion polymerization method by adding crosslinker--divinylbenzene （DVB） into the reaction system after polystyrene （PS） particles grew to -80% of the final size. When the amount of crosslinker DVB added was less than 6.17 wt% based on styrene, the prepared CPS particles were spherical and uniform and the size of the CPS particles could be predicted through the normal emulsion method. The glass transition temperature （Tg） of the prepared CPS particles was higher than that of un-crosslinked PS particles and, the more crosslinker that was added, the higher the Tg of CPS Particles. The prepared CPS particles had strong resistance to organic solvents.展开更多
The viscoelastic properties of the suspension of monodisperse spherical silica produced by hydrolysis of tetraethoxysilane in alcohol solvent with ammonia as a catalyst in polyethylene glycol （PEG） were studied. The...The viscoelastic properties of the suspension of monodisperse spherical silica produced by hydrolysis of tetraethoxysilane in alcohol solvent with ammonia as a catalyst in polyethylene glycol （PEG） were studied. The results show that the SiO2/PEG suspension possesses the reversible shear thinning and shear thickening behaviors. In the shear thinning region, the loss modulus （G＂） almost remains unchanged, whereas the storage modulus （G＇） decreases. In the shear thickening region, G＂ and G＇ increase for the formation of the ＂clusters＂. The larger G＂ over G＇ in all the stress studied shows that the system mainly possesses the viscous property, and that the energy dissipated（Ed） is larger than that stored. Ed of this suspension is proportional to the maximum strain （Tmax） rising with the exponent of 1.92 under low shear stress; however, in the shear thickening region, Ed is proportional to γ max rising with the exponent of 5.00.展开更多
Developing efficient and low-cost electrocatalysts is essential for the electroreduction of N_(2) to NH_(3).Here,highly monodispersed MoO_(3) clusters loaded on a coral-like CeO_(x)compound with abundant oxygen vacanc...Developing efficient and low-cost electrocatalysts is essential for the electroreduction of N_(2) to NH_(3).Here,highly monodispersed MoO_(3) clusters loaded on a coral-like CeO_(x)compound with abundant oxygen vacancies are successfully prepared by an impregnation-reduction method.The MoO_(3) clusters with small sizes of 2.6±0.5 nm are induced and anchored by the oxygen vacancies of CeO_(x),resulting in excellent nitrogen reduction reaction(NRR)performance.Additionally,the synergistic effects between MoO_(3) and CeO_(x)lead to a further improvement of the electrochemical performance.The as-prepared MoO_(3)-CeO_(x)catalyst shows an NH_(3) yield rate of 32.2 μg h^(-1) mg^(-1) cat and a faradaic efficiency of 7.04%at-0.75 V(vs.reversible hydrogen electrode)in 0.01 M Dulbecco’s Phosphate Buffered Saline.Moreover,it displays decent electrochemical stability over 30,000 s.Besides,the electrochemical NRR mechanism for MoO_(3)-CeO_(x)is investigated by in-situ Fourier transform infrared spectroscopy.N-H stretching,H-N-H bending,and N-N stretching are detected during the reaction,suggesting that an associative pathway is followed.This work provides an approach to designing and synthesizing potential electrocatalysts for NRR.展开更多
The emulsifier-free emulsion polymerization of N-hydroxymethyl acrylamide （NMA）, methyl methacrylate （MMA） and styrene （St） was successfully carried out under microwave irradiation, and monodisperse polymeric mi...The emulsifier-free emulsion polymerization of N-hydroxymethyl acrylamide （NMA）, methyl methacrylate （MMA） and styrene （St） was successfully carried out under microwave irradiation, and monodisperse polymeric microspheres were prepared. The experimental results show that the emulsifier-free emulsion polymerization under microwave irradiation has more rapid reaction rate, higher conversion and shorter induction time than the copolymerization with conventional heating. The apparent activation energies are 61.04 and 83.75 kJ/mol, respectively; the microspheres have spherical morphology, and the microspheres prepared by emulsifier-free emulsion polymerization under microwave irradiation are smaller, more uniform than those obtained with conventional heating.展开更多
Monodispersed manganese ferrite （MnFe2O4） nanocrystals could be successfully synthesized in large quantities via a facile synthetic technique based on the pyrolysis of organometallic compound precursor, in which oct...Monodispersed manganese ferrite （MnFe2O4） nanocrystals could be successfully synthesized in large quantities via a facile synthetic technique based on the pyrolysis of organometallic compound precursor, in which octadecene was used as solvent, and oleic acid and oleylamine were used as capping ligands. MnFe204 nanocrystals were obtained with size in a tunable range of 4- 15 nm and their morphologies could be tuned from spherical to triangle-shaped by varying the surfactants. The phase structure, morphology, and size of the products were characterized in detail by X-ray diffraction （XRD） and transmission electron microscopy （TEM）. Magnetic properties of MnFe2O4 nanocrystals with different morphologies were measured using a superconducting quantum interference device （SQUID）. Both monodisperse MnFe204 nanocrystals with spherical and triangle-shapes are superparamagnetic at room temperature while ferromagnetic at 2 K. The pyrolysis method may provide an effective route to synthesize other spinel ferrites or metal oxides nanocrystals.展开更多
In order to obtain the bio-moleculel LDHs nanocomposites having regular crystal structure,three nanocomposites of layered double hydroxides and polyoxyethylene sulfates were prepared by ion-exchange method.TEM analysi...In order to obtain the bio-moleculel LDHs nanocomposites having regular crystal structure,three nanocomposites of layered double hydroxides and polyoxyethylene sulfates were prepared by ion-exchange method.TEM analysis reveals that the monodisperse rigid sphere of approximately 200 nm in diameter could be gotten when the intergallery anion was PEGS-400.Such monodisperse nanoparticle could be used as a promising precursor for preparing bio-moleculel LDHs nanocomposites.展开更多
The formation mechanism of monodisperse polymer latex particles in the emulsifier-free emulsion polymerizationof methyl methacrylate and butyl acrylate with potassium persulfate as initiator was investigated. A multi-...The formation mechanism of monodisperse polymer latex particles in the emulsifier-free emulsion polymerizationof methyl methacrylate and butyl acrylate with potassium persulfate as initiator was investigated. A multi-step formationmechanism for the monodisperse polymer particles was proposed. The nucleation mechanism is considered to be thecoagulation of the precursor particles by homogeneous nucleation when the primary particles reach a critical size with highsurface charge density and sufficient stability. It had been proved by a special experiment that the early latex particles formedby the coagulation were stable. The primary particles grow by absorbing monomers and radicals in the polymerization systemand then become colloidally unstable again due to the understandable decrease of particle surface charge density, which leadsto the aggregation of the growing particles and the formation of larger latex pedicles therefrom. Aner the nucleation period,the preferential aggregation of the smaller particles in the propagation process leads to the change of the particles towards auniform size and narrower particle size distribution. The coexistence and competition of homogeneous nucleation,coagulation, propagation and aggregation result in the increase of the polydispersity index (U = D_(43)/D_(10)) in the first Stage,then its decrease in the later stage because of the competition of propagation and aggregation, and the gradual formation ofthe monodisperse particles.展开更多
基金financial support from the National Natural Science Foundation of China(22408196)financial support from the National Natural Science Foundation of China(22379082)+2 种基金the Natural Science Foundation of Shandong(ZR2022QB236)the supported by the State Key Laboratory of Clean and Efficient Coal Utilization,Taiyuan University of Technology(Grant No.MJNYSKL202402)the Taishan Scholars Program(tsqn201909119)。
文摘Cobalt selenide(CoSe_(2))anchored monodisperse Pt presents good acidic 2e^(-)oxygen reduction reaction(ORR)performance;however,conventional preparation methods can only yield ultra-low content of Pt atom catalysts.It is necessary to design catalysts with a high loading of monodisperse Pt to improve the activity and selectivity.Here,we reported anchoring highly reactive Pt atoms by constructing surface Co vacancies on CoSe_(2)(Pt_(1)/md-CoSe_(2)),thereby increasing the co ntent of Pt atoms.The monodisperse Pt is not only a reactive active site but also helps to improve the intrinsic activity of Co around Pt with a suitable electronic structu re,which contributes to the simultaneous enhancement of~*O_(2) adsorption and lowering of the reaction activation energy,accelerating the 2e^(-)ORR kinetics.The Pt_1/md-CoSe_(2) with a 0.2 wt%Pt exhibits high performa nce of electrocatalytic acidic 2e^(-)ORR.The H_(2)O_(2) yield is 1160.2 mmol g_(cat)^(-1).h^(-1)with a Faraday efficiency(FE)of 95.2%(0 V vs.RHE)at 0.1 M HClO_(4),superior to most of the reported literature.Moreover,the catalyst did not deactivate after a stability test of 30 h at the high current density of 100 mA cm^(-2).This work provides guidance for designing catalysts with applications and understanding the action mechanism of monodisperse Pt atoms.
基金V. ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China （No.21071136）, the National Basic Research Program of China （No.2010CB934700and No.2012CB932001）, the Research FUnd for the Doctoral Program of Higher Education of China （No.20103402110033） and Anhui Provincial Education Department （No.KJ2012ZD11）.
文摘Monodisperse Ag nanoparticles with diameters of about 3.4 nm were synthesized by a facile ultrasonic synthetic route at room temperature with the reduction of borane-tert-butylamine in the presence of oleylamine （OAm） and oleic acid （OA）. The reaction parameters of time, the molar ratios of OAm to OA were studied, and it was found that these parameters played important roles in the morphology and size of the products. Meanwhile, surface enhanced Raman spectrum （SERS） property suggested the Ag nanoparticles exhibited high SERS effect on the model molecule Rhodamine 6G. And also, two-photon fluorescence images showed that the silver nanoparticles had high performances in fluorescence enhancement.
基金Project (20776016) supported by the National Natural Science Foundation of ChinaProject (20876109) supported by Program for New Century Excellent Talents in University of China
文摘Monodisperse ZnxCd1-xS spheres were successfully fabricated with a high yield by a facile hydrothermal route.The as-prepared samples were characterized by X-ray diffractometry,scanning electron microscopy and UV-vis diffusion reflectance spectroscopy.The results indicate that all the prepared samples have the same hexagonal wurtzite phase and exhibit good size uniformity and regularity.Degradation of rhodamine-B（RhB） was used to evaluate the photocatalytic activities of ZnxCd1-xS samples.Zn0.4Cd0.6S possessed the best photocatalytic activity and exhibited high stability during the reaction.
基金supported by the National Basic Research Program of China (Grant No.2007CB613603)
文摘Monodisperse spherical SiO2 particles were successfully synthesized in 2-propanol-H2O-NH3 system by the microwave hydrothermal method using ammonia as catalyst. To investigate the influences on the size of spherical SiO2 particles, factors such as ammonia concentration, reaction temperature, stirring intensity and reactants mol ratio have been studied. The orthogonal experiments were carried out. The as-prepared SiO2 particles were characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, Fourier transform infrared spectroscopy （FTIR） and differential thermal analysis （DTA）. The results indicated that the size of SiO2 particles increased greatly with the increase in ammonia concentration, temperature and reactants mol ratio, but increased slightly with the increase in stirring intensity. Monodisperse spherical Si02 particles were amorphous with perfect sphere and uniform size. Hydroxyl was detected in SiO2. Kinetic parameters were calculated, and finally the reaction rate equation of dehydrated hydroxyl was obtained.
基金supported by the Self-determined Research Program of Jiangnan University(Nos.JUSRP11214 and JUSRP 51319B to JY)
文摘In this work, we describe the one-pot synthesis of PEGylated mesoporous silica nanoparticles （MSNs） with uniform shape, tunable sizes, and narrow size distributions. The size of these nanoparticles can be controlled from 49 nm to 98 nm by simply varying the concentration oftriethanolamine during the base- catalyzed sol-gel reaction. Particles were characterized by transmission electron microscopy, dynamic light scattering, Fourier transform infrared spectrometry, thermogravimetric analysis, and nitrogen adsorption-desorption measurements. These PEGylated MSNs exhibited excellent long-term stability in biological media, which ensures their potential applications in drug delivery.
基金This work was funded by the financial support of the National Natural Science Foundation of China(Project No.20274018)Nankai University.
文摘Monodisperse crosslinked poly(chloromethylstyrene-co-divinylbenzene)(poly(CMSt-co-DVB))microsphereswere prepared by distillation-precipitation copolymerization of chloromethylstyrene(CMSt)and divinylbenzene(DVB)inneat acetonitrile.The polymer particles had clean surfaces due to the absence of any added stabilizer.The size of the particlesranges from 2.59 μm to 3.19 μm and with mono-dispersity around 1.002-1.014.The effects of monomer feed incopolymerization on the microsphere formation were described.The polymer microspheres were characterized by SEM andchlorinity elemental analysis.
文摘Monodisperse titania glycolate submicrospheres were synthesized by a modified sol-gel route, in which ultrasonic treatment was introduced to improve the reaction efficiency. The as-prepared products were characterized by means of Fourier transform infrared spectrum （FT-IR）, transmission electron microscopy （TEM）, powder X-ray diffraction （XRD）, and scanning electron microscopy （SEM）. The results indicate that the as-prepared products are titania glycolate submicrospheres with diameters of 230-330 nm. The average particle diameter is estimated to be about 280 nm. Ultrasonic treatment has an important influence on the morphology of the produced titania glycolates. After calcination at 450°C for 2 h, these titania glycolates were completely converted into anatase TiO2. The morphology of TiO2 particles was well reserved during the calcination process except for a reduction of 18% in the average particle size.
基金supported by Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘Abstract： Uniform Er3A15O12 spheres are of great value for fabricating optical ceramics. The highly monodisperse and size-controllable erbium aluminum garnet （EAG） precursors for transparent ceramics were successfully synthesized through a new microwave process. The precursors constituted of ultrafine particles joining together by a hydroxyls formed compact network structure in the absence of SO42 , however, the morphologies of the precursors exhibited spheres with trace amount of SO42-. With manipulated programming of microwave irradiation parameters, narrow distributed particles of 40-50 nm were finally obtained by a separation of nu- cleation and nanocrystal growth. The mechanism behind the influence of microwave irradiation parameters on the growth of EAG precursors was preliminarily analysed. Easily dispersible and pure phase EAG were obtained at 950℃. The as-prepared EAG powders were used to fabricate transparent ceramics and transparent polycrystalline EAG ceramics were obtained under hydrogen furnace at 1750℃ for 8 h.
基金Supported by the National Natural Science Foundation of China under Grant Nos 51571135,11274214 and 61434002the Special Funds of Shanxi Scholars Program under Grant No IRT1156+1 种基金Collaborative Innovation Center for Shanxi Advanced Permanent Materials and Technologythe Special Funds of the Ministry of Education of China under Grant No 20121404130001
文摘Magnetite （Fe3O4） nanoparticles with different sizes and shapes are synthesized by the thermal decomposition method. Two approaches, non-injection one-pot and hot-injection methods, are designed to investigate the growth mechanism in detail. It is found that the size and shape of nanoparticles are determined by adjusting the precursor concentration and duration time, which can be well explained by the mechanism based on the LaMer model in our synthetic system. The monodisperse Fe3O4 nanoparticles have a mean diameter from 5nm to 16nm, and shape evolution from spherical to triangular and cubic. The magnetic properties are size-dependent, and Fe3O4 nanoparticles in small size about 5 nm exhibit superparamagnetie properties at room temperature and maximum saturation magnetization approaches to 78 emu/g, whereas Fe3O4 nanoparticles develop ferromagnetic properties when the diameter increases to about 16nm.
基金National Natural Science Foundation of China(51873079)for financial support。
文摘Simultaneous achievement in high solid content and high microsphere yield is deemed a challenge in the fabrication of monodisperse microspheres by precipitation polymerization.We herein demonstrate that micro-sized monodisperse poly(methacrylic monomer-divinylbenzene)microspheres containing epoxy,lauyl,carboxyl and hydroxyl functions can be fabricated by solvothermal precipitation copolymerization at 20%(mass)monomer loading with over 94%microsphere yield.The morphology and porosity of the obtained particles can be readily tuned by cosolvent-acetonitrile binary solvents.Addition of a small amount of cosolvent that has similar solubility parameter to that of the functional monomer can significantly improve the monodispersity of the obtained microspheres.When tetrahydrofuran was used as the co-solvent,the surface area of the highly porous microspheres achieved higher than 400 m^(2)·g^(-1).Solvothermal precipitation co-polymerization can be expected in scale-up fabrication of various monodisperse functional microspheres free of any surfactant and additive.
文摘The active sites of monodisperse transition metal Ni-clusters were anchored on carbon nitride(CN)by an in situ photoreduction deposition method to promote the efficient separation of photogenerated charges and achieve high-efficiency photocatalytic activity for hydrogen evolution.The Ni-cluster/CN exhibited a photocatalytic hydrogen production rate of 16.5 mmol·h^(-1)·g^(-1) and a total turnover frequency(TOF(H_(2)))value of 461.14 h^(-1).X-ray absorption spectroscopy based on synchrotron radiation indicated that CN had two reaction centers to form stable interface interactions with monodispersed Ni-clusters,in which carbon can act as an electron acceptor,while nitrogen can act as an electron donor.Meanwhile,the hybrid electronic structure of the Ni-cluster/CN system was constructed,which was favorable for photocatalytic activity for hydrogen production.An in-depth understanding of the interfacial interaction between CN and Ni-clusters will have important reference significance on the mechanistic study of development based on the cocatalyst.
文摘Monodispersed microsized copper oxalate particles were prepared in a segmented continuous flow tube reactor, and the effect of the main parameters such as organic additive agent, initial copper ions concentration, residence time, and segmented media on the final products were investigated experimentally. The obtained copper oxalate microsized particles were disc-like in the presence of citrate ligand,which was the shape inducer for the precipitated copper oxalate. Thermodynamic equilibrium diagrams of the Cu(Ⅱ)-oxalate-H_2O,Cu(Ⅱ)-oxalate-citrate-H_2O, and Cu(Ⅱ)-oxalate-EDTA-H_2O solution systems were drawn to estimate the possible copper species under the experimental conditions and to explain the formation mechanisms of copper oxalate particles in the segmented fluidic reactor. Both theoretical and experimental results indicated that the presence of chelating reagents such as citrate and EDTA had distinct effect on the evolution of particle shape. Air and kerosene were tested as media for the fluidic flow segmentation, and the latter was verified to better promote the growth of copper oxalate particles. The present study provides an easy method to prepare monodispersed copper oxalate microsized particles in a continuous scaling-up way, which can be utilized to prepare the precursor material for conductive inks.
基金supported by the National Natural Science Foundation of China(51974209)the Outstanding Doctoral Award Fund in Shanxi Province(20202017)。
文摘Lithium sulfur battery(LSB)is a promising energy storage system to meet the increasing energy demands for electric vehicles and smart grid,while its wide commercialization is severely inhibited by the"shuttle effect"of polysulfides,low utilization of sulfur cathode,and safety of lithium anode.To overcome these issues,herein,monodisperse polar NiCo_(2)O_(4)nanoparticles decorated porous graphene aerogel composite(NCO-GA)is proposed.The aerogel composite demonstrates high conductivity,hierarchical porous structure,high chemisorption capacity and excellent electrocatalytic ability,which effectively inhibits the"shuttle effect",promotes the ion/electron transport and increases the reaction kinetics.The NCO-GA/S cathode exhibits high discharge specific capacity(1214.1 mAh g^(-1)at 0.1 C),outstanding rate capability(435.7 mAh g^(-1)at 5 C)and remarkable cycle stability(decay of 0.031%/cycle over 1000 cycles).Quantitative analyses show that the physical adsorption provided by GA mainly contributes to the capacity of NCO-GA/S at low rate,while the chemical adsorption provided by polar NiCo_(2)O_(4)contributes mainly to the capacity of NCO-GA/S with the increase of current density and cycling.This work provides a new strategy for the design of GA-based composite with synergistic adsorption and electrocatalytic activity for the potential applications in LSB and related energy fields.
基金National Basic Research Program of China(Grant No:2006CB932601)the Scientific Research Foundation for Returned Overseas Chinese Scholar,Ministry of Education
文摘Monodisperse crosslinked polystyrene （CPS） particles were prepared through the normal emulsion polymerization method by adding crosslinker--divinylbenzene （DVB） into the reaction system after polystyrene （PS） particles grew to -80% of the final size. When the amount of crosslinker DVB added was less than 6.17 wt% based on styrene, the prepared CPS particles were spherical and uniform and the size of the CPS particles could be predicted through the normal emulsion method. The glass transition temperature （Tg） of the prepared CPS particles was higher than that of un-crosslinked PS particles and, the more crosslinker that was added, the higher the Tg of CPS Particles. The prepared CPS particles had strong resistance to organic solvents.
基金Projects(50774096 50606017) supported by the National Natural Science Foundation of China
文摘The viscoelastic properties of the suspension of monodisperse spherical silica produced by hydrolysis of tetraethoxysilane in alcohol solvent with ammonia as a catalyst in polyethylene glycol （PEG） were studied. The results show that the SiO2/PEG suspension possesses the reversible shear thinning and shear thickening behaviors. In the shear thinning region, the loss modulus （G＂） almost remains unchanged, whereas the storage modulus （G＇） decreases. In the shear thickening region, G＂ and G＇ increase for the formation of the ＂clusters＂. The larger G＂ over G＇ in all the stress studied shows that the system mainly possesses the viscous property, and that the energy dissipated（Ed） is larger than that stored. Ed of this suspension is proportional to the maximum strain （Tmax） rising with the exponent of 1.92 under low shear stress; however, in the shear thickening region, Ed is proportional to γ max rising with the exponent of 5.00.
基金financially supported by the National Key Research and Development Program of China(2017YFA0206500)NSFC(Grant Nos.21673198,91934303,21621091)。
文摘Developing efficient and low-cost electrocatalysts is essential for the electroreduction of N_(2) to NH_(3).Here,highly monodispersed MoO_(3) clusters loaded on a coral-like CeO_(x)compound with abundant oxygen vacancies are successfully prepared by an impregnation-reduction method.The MoO_(3) clusters with small sizes of 2.6±0.5 nm are induced and anchored by the oxygen vacancies of CeO_(x),resulting in excellent nitrogen reduction reaction(NRR)performance.Additionally,the synergistic effects between MoO_(3) and CeO_(x)lead to a further improvement of the electrochemical performance.The as-prepared MoO_(3)-CeO_(x)catalyst shows an NH_(3) yield rate of 32.2 μg h^(-1) mg^(-1) cat and a faradaic efficiency of 7.04%at-0.75 V(vs.reversible hydrogen electrode)in 0.01 M Dulbecco’s Phosphate Buffered Saline.Moreover,it displays decent electrochemical stability over 30,000 s.Besides,the electrochemical NRR mechanism for MoO_(3)-CeO_(x)is investigated by in-situ Fourier transform infrared spectroscopy.N-H stretching,H-N-H bending,and N-N stretching are detected during the reaction,suggesting that an associative pathway is followed.This work provides an approach to designing and synthesizing potential electrocatalysts for NRR.
基金Funded by the Natural Science Foundation of Hubei Province (2010CDB04603)the Educational Commission of Hubei Province (Q200610004)
文摘The emulsifier-free emulsion polymerization of N-hydroxymethyl acrylamide （NMA）, methyl methacrylate （MMA） and styrene （St） was successfully carried out under microwave irradiation, and monodisperse polymeric microspheres were prepared. The experimental results show that the emulsifier-free emulsion polymerization under microwave irradiation has more rapid reaction rate, higher conversion and shorter induction time than the copolymerization with conventional heating. The apparent activation energies are 61.04 and 83.75 kJ/mol, respectively; the microspheres have spherical morphology, and the microspheres prepared by emulsifier-free emulsion polymerization under microwave irradiation are smaller, more uniform than those obtained with conventional heating.
基金Project(2010QZZD008) supported by the Prospect Key Projects of Fundamental Research Funds for the Central UniversitiesProject(2007FJ3008) supported by the Hunan Provincial Key Science and Technology Program of China
文摘Monodispersed manganese ferrite （MnFe2O4） nanocrystals could be successfully synthesized in large quantities via a facile synthetic technique based on the pyrolysis of organometallic compound precursor, in which octadecene was used as solvent, and oleic acid and oleylamine were used as capping ligands. MnFe204 nanocrystals were obtained with size in a tunable range of 4- 15 nm and their morphologies could be tuned from spherical to triangle-shaped by varying the surfactants. The phase structure, morphology, and size of the products were characterized in detail by X-ray diffraction （XRD） and transmission electron microscopy （TEM）. Magnetic properties of MnFe2O4 nanocrystals with different morphologies were measured using a superconducting quantum interference device （SQUID）. Both monodisperse MnFe204 nanocrystals with spherical and triangle-shapes are superparamagnetic at room temperature while ferromagnetic at 2 K. The pyrolysis method may provide an effective route to synthesize other spinel ferrites or metal oxides nanocrystals.
文摘In order to obtain the bio-moleculel LDHs nanocomposites having regular crystal structure,three nanocomposites of layered double hydroxides and polyoxyethylene sulfates were prepared by ion-exchange method.TEM analysis reveals that the monodisperse rigid sphere of approximately 200 nm in diameter could be gotten when the intergallery anion was PEGS-400.Such monodisperse nanoparticle could be used as a promising precursor for preparing bio-moleculel LDHs nanocomposites.
文摘The formation mechanism of monodisperse polymer latex particles in the emulsifier-free emulsion polymerizationof methyl methacrylate and butyl acrylate with potassium persulfate as initiator was investigated. A multi-step formationmechanism for the monodisperse polymer particles was proposed. The nucleation mechanism is considered to be thecoagulation of the precursor particles by homogeneous nucleation when the primary particles reach a critical size with highsurface charge density and sufficient stability. It had been proved by a special experiment that the early latex particles formedby the coagulation were stable. The primary particles grow by absorbing monomers and radicals in the polymerization systemand then become colloidally unstable again due to the understandable decrease of particle surface charge density, which leadsto the aggregation of the growing particles and the formation of larger latex pedicles therefrom. Aner the nucleation period,the preferential aggregation of the smaller particles in the propagation process leads to the change of the particles towards auniform size and narrower particle size distribution. The coexistence and competition of homogeneous nucleation,coagulation, propagation and aggregation result in the increase of the polydispersity index (U = D_(43)/D_(10)) in the first Stage,then its decrease in the later stage because of the competition of propagation and aggregation, and the gradual formation ofthe monodisperse particles.
