Hollow Bi2WO6 microspheres are successfully synthesized by a facile ultrasonic spray pyrolysis（USP） method using NaCl as a salt template.The as-prepared hollow microspheres assembled as nanoplates with dimensions of...Hollow Bi2WO6 microspheres are successfully synthesized by a facile ultrasonic spray pyrolysis（USP） method using NaCl as a salt template.The as-prepared hollow microspheres assembled as nanoplates with dimensions of approximately 41-148 nm and are dispersed with non-uniform pores on the template surface.By swapping the salt template with KC1 or Na2SO4,different morphologies of Bi2WO6 are obtained.The experimental results demonstrate that NaCl plays a key role on the formation of Bi2WO6 with hollow structures.The specific growth mechanism of hollow microspheres was studied in detail.The Bi2WO6 hollow microspheres exhibit an excellent photocatalytic efficiency for NO removal under solar light irradiation,which is 1.73 times higher than for the Bi2WO6 obtained in the absence of any salt template.This enhancement can be ascribed to the simultaneous improvement on the surface area and visible light-harvesting ability from the hollow structures.Electron spin resonance（ESR） results suggest that both radicals of ·OH and ·O2^- are involved in the photocatalytic process over the BWO-NaCl sample.The production of ·O2^- radicals offers better durability for NO removal.展开更多
As promising energy storage systems,lithium-sulfur(Li-S)batteries have attracted significant attention because of their ultra-high energy densities.However,Li-S battery suffers problems related to the complex phase co...As promising energy storage systems,lithium-sulfur(Li-S)batteries have attracted significant attention because of their ultra-high energy densities.However,Li-S battery suffers problems related to the complex phase conversion that occurs during the charge-discharge process,particularly the deposition of solid Li2S from the liquid-phase polysulfides,which greatly limits its practical application.In this paper,edge-rich MoS2/C hollow microspheres(Edg-MoS2/C HMs)were designed and used to functionalize separator for Li-S battery,resulting in the uniform deposition of Li2S.The microspheres were fabricated through the facile hydrothermal treatment of MoO3-aniline nanowires and a subsequent carbonization process.The obtained Edg-MoS2/C HMs have a strong chemical absorption capability and high density of Li2S binding sites,and exhibit excellent electrocatalytic performance and can effectively hinder the polysulfide shuttle effect and guide the uniform nucleation and growth of Li2S.Furthermore,we demonstrate that the Edg-MoS2/C HMs can effectively regulate the deposition of Li2S and significantly improve the reversibility of the phase conversion of the active sulfur species,especially at high sulfur loadings and high C-rates.As a result,a cell containing a separator functionalized with Edg-MoS2/C HMs exhibited an initial discharge capacity of 935 mAh g-1 at 1.0 C and maintained a capacity of 494 mAh g-1 after 1000 cycles with a sulfur loading of 1.7 mg cm-2.Impressively,at a high sulfur loading of 6.1 mg cm-2 and high rate of 0.5 C,the cell still delivered a high reversible discharge capacity of 478 mAh g-1 after 300 cycles.This work provides fresh insights into energy storage systems related to complex phase conversions.展开更多
Constructing a step-scheme heterojunction at the interface between two semiconductors is an efficient way to optimize the redox ability and accelerate the charge carrier separation of a photocatalytic system for achie...Constructing a step-scheme heterojunction at the interface between two semiconductors is an efficient way to optimize the redox ability and accelerate the charge carrier separation of a photocatalytic system for achieving high photocatalytic performance.In this study,we prepared a hierarchical ZnO@ZnS step-scheme photocatalyst by incorporating ZnS into the outer shell of hollow ZnO microspheres via a simple in situ sulfidation strategy.The ZnO@ZnS step-scheme photocatalysts had a large surface area,high light utilization capacity,and superior separation efficiency for photogenerated charge carriers.In addition,the material simulation revealed that the formation of the step-scheme heterojunction between ZnO and ZnS was due to the presence of the built-in electric field.Our study paves the way for design of high-performance photocatalysts for H_(2) production.展开更多
Hierarchical Sb_2S_3 hollow microspheres assembled by nanowires have been successfully synthesized by a simple and practical hydrothermal reaction. The possible formation process of this architecture was investigated ...Hierarchical Sb_2S_3 hollow microspheres assembled by nanowires have been successfully synthesized by a simple and practical hydrothermal reaction. The possible formation process of this architecture was investigated by X-ray diffraction, focused-ion beam-scanning electron microscopy dual-beam system, and transmission electron microscopy. When used as the anode material for lithium-ion batteries, Sb_2S_3 hollow microspheres manifest excellent rate property and enhanced lithium-storage capability and can deliver a discharge capacity of 674 m Ah g^(-1) at a current density of 200 m A g^(-1) after 50 cycles. Even at a high currentdensity of 5000 m A g^(-1), a discharge capacity of541 m Ah g^(-1) is achieved. Sb_2S_3 hollow microspheres also display a prominent sodium-storage capacity and maintain a reversible discharge capacity of 384 m Ah g^(-1) at a current density of 200 m A g^(-1) after 50 cycles. The remarkable lithium/sodium-storage property may be attributed to the synergetic effect of its nanometer size and three-dimensional hierarchical architecture, and the outstanding stability property is attributed to the sufficient interior void space,which can buffer the volume expansion.展开更多
TiO2hollow microspheres(TiO2‐HMSs)have attracted much attention because of their high photoreactivity,low density,and good permeability.However,anatase TiO2‐HMSs have poor thermal stability.In this study,surface‐fl...TiO2hollow microspheres(TiO2‐HMSs)have attracted much attention because of their high photoreactivity,low density,and good permeability.However,anatase TiO2‐HMSs have poor thermal stability.In this study,surface‐fluorinated TiO2‐HMSs were assembled from hollow nanoparticles by the hydrothermal reaction of the mixed Ti(SO4)2–NH4HF–H2O2solution at180°C.The effect of the calcination temperature on the structure and photoreactivity of the TiO2‐HMSs was systematically investigated,which was evaluated by photocatalytic oxidation of acetone in air under ultraviolet irradiation.We found that after calcination at300°C,the photoreactivity of the TiO2‐HMSs decreases from1.39×10?3min?1(TiO2‐HMS precursor)to0.82×10?3min?1because of removal of surface‐adsorbed fluoride ions.With increasing calcination temperature from300to900°C,the building blocks of the TiO2‐HMSs evolve from truncated bipyramidal shaped hollow nanoparticles to round solid nanoparticles,and the photoreactivity of the TiO2‐HMSs steady increases from0.82×10?3to2.09×10?3min?1because of enhanced crystallization.Further increasing the calcination temperature to1000and1100°C results in a decrease of the photoreactivity,which is ascribed to a sharp decrease of the Brunauer–Emmett–Teller surface area and the beginning of the anatase–rutile phase transformation at1100°C.The effect of surface‐adsorbed fluoride ions on the thermal stability of the TiO2‐HMSs is also discussed.展开更多
Al2 O3 hollow microspheres without noticeable aggregation have been prepared via a facile templating route with urea-mediated precipitation. The precipitation process is different from the surfaceadsorption method whi...Al2 O3 hollow microspheres without noticeable aggregation have been prepared via a facile templating route with urea-mediated precipitation. The precipitation process is different from the surfaceadsorption method which is confined to the adsorption capacity of the template surface. TEM and SEM images indicate that most of these Al2 O3 hollow microspheres with shell thickness of tens of nanometers and diameters in a narrow range of 100-200 nm consist of a shell of closely packed nanoparticles. The optimal amount of H2 O and EtOH are 40 and 120 m L, respectively. The specific surface area, average pore size and pore volume of the Al2 O3 hollow microspheres（calcinated at 600 ℃） are 328.52 m2/g, 17.496 nm and 1.985 cm3/g, respectively. As the calcination temperature increases from 600 to 1 100 ℃, the phase composition changes from γ-Al2 O3 to θ-Al2 O3 and a-Al2 O3, and the surface morphology appears to change from a relatively rough surface formed by nanoparticles to a smooth surface formed by lamellar, which lead to the closure of pore channels and the reduction of specific surface.展开更多
A hollow glass microsphere(HGM)/TiO2 composite hollow sphere was successfully prepared via a simple precipitation method.The TiO2 coating layers grew on the surface of the HGMs that range from 20 to 50μm in diameter ...A hollow glass microsphere(HGM)/TiO2 composite hollow sphere was successfully prepared via a simple precipitation method.The TiO2 coating layers grew on the surface of the HGMs that range from 20 to 50μm in diameter as nanoparticles with the formation of the SiO Ti bonds.The growth mechanism accounting for the formation of the TiO2 nanolayers was proposed.The morphology,composition,thermal insulation properties,and visible-near infrared(VIS-NIR)refl ectance of the HGMs/TiO2 composite hollow spheres were characterized.The VIS-NIR reflectance of the HGMs/TiO2 composite hollow spheres increased by more than 30%compared to raw HGMs.The thermal conductivity of the particles is 0.058 W/(m K).The result indicates that the VIS-NIR reflectance of the composite hollow spheres is strongly influenced by the coating of TiO2.The composite hollow spheres were used as the main functional filler to prepare the organic-inorganic composite coatings.The glass substrates coated by the organic-inorganic coatings had lower thermal conductivity and higher near infrared reflectivity.Therefore,the HGMs/TiO2 composite hollow spheres can reflect most of the solar energy and effectively keep out the heat as a thermal insulation coating for energy-saving constructions.展开更多
Core-shell structured SiO2/poly（N-isopropylacrylamide） （SiO2/PNIPAM） microspheres were successfully fabricated through hydrolysis and condensation reaction of tertraethyl orthosilicate （TEOS） on the surface of P...Core-shell structured SiO2/poly（N-isopropylacrylamide） （SiO2/PNIPAM） microspheres were successfully fabricated through hydrolysis and condensation reaction of tertraethyl orthosilicate （TEOS） on the surface of PNIPAM template at 50 ~C. The PNIPAM template can be easily removed by water at room temperature so that SiO2 hollow microspheres were finally obtained. The transmission electron microscope and scanning electron microscope observations indicated that SiO2 hollow microspheres with an average diameter of 150 nm can be formed only if there are enough concentration of PNIPAM and TEOS, and the hy- drolysis time of TEOS. FTIR analysis showed that part of PNIPAM remained on the wall of SiO2 because of the strong interaction between PNIPAM and silica. This work provides a clean and efficient way to prepare hollow microspheres.展开更多
In order to improve the lower practical capacity and bad cyclability of crystalline V2O5（c-V2O5）,the vanadium oxide（V2O5） and polypyrrole（PPy） hybrid with hollow-spherical（HS） structure was studied.HS nanocomp...In order to improve the lower practical capacity and bad cyclability of crystalline V2O5（c-V2O5）,the vanadium oxide（V2O5） and polypyrrole（PPy） hybrid with hollow-spherical（HS） structure was studied.HS nanocomposite comprised of conductive polypyrrole and vanadium pentoxide（PPy/V2O5） was synthesized by polymerization of pyrrole monomer（Py） in the hollow-microspherical V2O5 host.This novel hybrid was characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM） and tested as the cathode material for lithium-ion batteries（LIB） by galvanostatic cell cycling and electrochemical impedance spectroscopy（EIS）.The hollow-spherical polypyrrole/vanadium oxide（HS-PPy/V2O5） composites,in which PPy molecules are intercalated between the layers of V2O5,exhibit slight reduced capacity and substantially improve cyclability and electrochemical activity compared with the pure HS-V2O5.展开更多
Recently,rechargeable zinc-ion batteries have been considered as the future development direction of large-scale energy storage due to their low price,safety,environmental friendliness,and excellent electrochemical pe...Recently,rechargeable zinc-ion batteries have been considered as the future development direction of large-scale energy storage due to their low price,safety,environmental friendliness,and excellent electrochemical performance.However,highcapacity,long-cycle stable cathode materials that can meet the demand are still to be developed.Herein,the hollow mesoporous ZnMn2O4/C microsphere cathode material with carbon nanotubes embedded in the shell was prepared by spray pyrolysis for the first time.Its capacity remained at 209.71 mAh·g−1 after 150 cycles at a rate of 0.5 A·g−1,and still maintained a specific capacity of 100.06 mAh·g−1 at a rate of 1 A·g−1 after 1,000 cycles.The outstanding performance is attributed to the hollow structure that can effectively buffer large volume changes caused by ion intercalation and deintercalation,excellent porosity,cationic defects,and high electrical conductivity of carbon nanotubes and its strong adsorption to ZnMn2O4 nanoparticles.展开更多
基金supported by the National Natural Science Foundation of China (41503102, 41401567, 41573138)the China Postdoctoral Science Foundation (2015M572568)~~
文摘Hollow Bi2WO6 microspheres are successfully synthesized by a facile ultrasonic spray pyrolysis（USP） method using NaCl as a salt template.The as-prepared hollow microspheres assembled as nanoplates with dimensions of approximately 41-148 nm and are dispersed with non-uniform pores on the template surface.By swapping the salt template with KC1 or Na2SO4,different morphologies of Bi2WO6 are obtained.The experimental results demonstrate that NaCl plays a key role on the formation of Bi2WO6 with hollow structures.The specific growth mechanism of hollow microspheres was studied in detail.The Bi2WO6 hollow microspheres exhibit an excellent photocatalytic efficiency for NO removal under solar light irradiation,which is 1.73 times higher than for the Bi2WO6 obtained in the absence of any salt template.This enhancement can be ascribed to the simultaneous improvement on the surface area and visible light-harvesting ability from the hollow structures.Electron spin resonance（ESR） results suggest that both radicals of ·OH and ·O2^- are involved in the photocatalytic process over the BWO-NaCl sample.The production of ·O2^- radicals offers better durability for NO removal.
基金financially supported by National Natural Science Foundation of China (No. 51672083)Program of Shanghai Academic/Technology Research Leader (18XD1401400)+3 种基金Basic Research Program of Shanghai (17JC1404702)Leading talents in Shanghai in 2018The 111 project (B14018)the Fundamental Research Funds for the Central Universities (222201718002)
文摘As promising energy storage systems,lithium-sulfur(Li-S)batteries have attracted significant attention because of their ultra-high energy densities.However,Li-S battery suffers problems related to the complex phase conversion that occurs during the charge-discharge process,particularly the deposition of solid Li2S from the liquid-phase polysulfides,which greatly limits its practical application.In this paper,edge-rich MoS2/C hollow microspheres(Edg-MoS2/C HMs)were designed and used to functionalize separator for Li-S battery,resulting in the uniform deposition of Li2S.The microspheres were fabricated through the facile hydrothermal treatment of MoO3-aniline nanowires and a subsequent carbonization process.The obtained Edg-MoS2/C HMs have a strong chemical absorption capability and high density of Li2S binding sites,and exhibit excellent electrocatalytic performance and can effectively hinder the polysulfide shuttle effect and guide the uniform nucleation and growth of Li2S.Furthermore,we demonstrate that the Edg-MoS2/C HMs can effectively regulate the deposition of Li2S and significantly improve the reversibility of the phase conversion of the active sulfur species,especially at high sulfur loadings and high C-rates.As a result,a cell containing a separator functionalized with Edg-MoS2/C HMs exhibited an initial discharge capacity of 935 mAh g-1 at 1.0 C and maintained a capacity of 494 mAh g-1 after 1000 cycles with a sulfur loading of 1.7 mg cm-2.Impressively,at a high sulfur loading of 6.1 mg cm-2 and high rate of 0.5 C,the cell still delivered a high reversible discharge capacity of 478 mAh g-1 after 300 cycles.This work provides fresh insights into energy storage systems related to complex phase conversions.
文摘Constructing a step-scheme heterojunction at the interface between two semiconductors is an efficient way to optimize the redox ability and accelerate the charge carrier separation of a photocatalytic system for achieving high photocatalytic performance.In this study,we prepared a hierarchical ZnO@ZnS step-scheme photocatalyst by incorporating ZnS into the outer shell of hollow ZnO microspheres via a simple in situ sulfidation strategy.The ZnO@ZnS step-scheme photocatalysts had a large surface area,high light utilization capacity,and superior separation efficiency for photogenerated charge carriers.In addition,the material simulation revealed that the formation of the step-scheme heterojunction between ZnO and ZnS was due to the presence of the built-in electric field.Our study paves the way for design of high-performance photocatalysts for H_(2) production.
基金supported financially by the National Natural Foundation of China(Grant No.51672234)the Research Foundation for Hunan Youth Outstanding People from Hunan Provincial Science and Technology Department(2015RS4030)+1 种基金Hunan 2011 Collaborative Innovation Center of Chemical Engineering&Technology with Environmental Benignity and Effective Resource UtilizationProgram for Innovative Research Cultivation Team in University of Ministry of Education of China(1337304)
文摘Hierarchical Sb_2S_3 hollow microspheres assembled by nanowires have been successfully synthesized by a simple and practical hydrothermal reaction. The possible formation process of this architecture was investigated by X-ray diffraction, focused-ion beam-scanning electron microscopy dual-beam system, and transmission electron microscopy. When used as the anode material for lithium-ion batteries, Sb_2S_3 hollow microspheres manifest excellent rate property and enhanced lithium-storage capability and can deliver a discharge capacity of 674 m Ah g^(-1) at a current density of 200 m A g^(-1) after 50 cycles. Even at a high currentdensity of 5000 m A g^(-1), a discharge capacity of541 m Ah g^(-1) is achieved. Sb_2S_3 hollow microspheres also display a prominent sodium-storage capacity and maintain a reversible discharge capacity of 384 m Ah g^(-1) at a current density of 200 m A g^(-1) after 50 cycles. The remarkable lithium/sodium-storage property may be attributed to the synergetic effect of its nanometer size and three-dimensional hierarchical architecture, and the outstanding stability property is attributed to the sufficient interior void space,which can buffer the volume expansion.
基金supported by the National Natural Science Foundation of China(51672312,21373275)the Science and Technology Program of Wuhan,China(2016010101010018,2015070504020220)the Dean’s Research Fund–04257 from the Education University of Hong Kong~~
文摘TiO2hollow microspheres(TiO2‐HMSs)have attracted much attention because of their high photoreactivity,low density,and good permeability.However,anatase TiO2‐HMSs have poor thermal stability.In this study,surface‐fluorinated TiO2‐HMSs were assembled from hollow nanoparticles by the hydrothermal reaction of the mixed Ti(SO4)2–NH4HF–H2O2solution at180°C.The effect of the calcination temperature on the structure and photoreactivity of the TiO2‐HMSs was systematically investigated,which was evaluated by photocatalytic oxidation of acetone in air under ultraviolet irradiation.We found that after calcination at300°C,the photoreactivity of the TiO2‐HMSs decreases from1.39×10?3min?1(TiO2‐HMS precursor)to0.82×10?3min?1because of removal of surface‐adsorbed fluoride ions.With increasing calcination temperature from300to900°C,the building blocks of the TiO2‐HMSs evolve from truncated bipyramidal shaped hollow nanoparticles to round solid nanoparticles,and the photoreactivity of the TiO2‐HMSs steady increases from0.82×10?3to2.09×10?3min?1because of enhanced crystallization.Further increasing the calcination temperature to1000and1100°C results in a decrease of the photoreactivity,which is ascribed to a sharp decrease of the Brunauer–Emmett–Teller surface area and the beginning of the anatase–rutile phase transformation at1100°C.The effect of surface‐adsorbed fluoride ions on the thermal stability of the TiO2‐HMSs is also discussed.
文摘Al2 O3 hollow microspheres without noticeable aggregation have been prepared via a facile templating route with urea-mediated precipitation. The precipitation process is different from the surfaceadsorption method which is confined to the adsorption capacity of the template surface. TEM and SEM images indicate that most of these Al2 O3 hollow microspheres with shell thickness of tens of nanometers and diameters in a narrow range of 100-200 nm consist of a shell of closely packed nanoparticles. The optimal amount of H2 O and EtOH are 40 and 120 m L, respectively. The specific surface area, average pore size and pore volume of the Al2 O3 hollow microspheres（calcinated at 600 ℃） are 328.52 m2/g, 17.496 nm and 1.985 cm3/g, respectively. As the calcination temperature increases from 600 to 1 100 ℃, the phase composition changes from γ-Al2 O3 to θ-Al2 O3 and a-Al2 O3, and the surface morphology appears to change from a relatively rough surface formed by nanoparticles to a smooth surface formed by lamellar, which lead to the closure of pore channels and the reduction of specific surface.
文摘A hollow glass microsphere(HGM)/TiO2 composite hollow sphere was successfully prepared via a simple precipitation method.The TiO2 coating layers grew on the surface of the HGMs that range from 20 to 50μm in diameter as nanoparticles with the formation of the SiO Ti bonds.The growth mechanism accounting for the formation of the TiO2 nanolayers was proposed.The morphology,composition,thermal insulation properties,and visible-near infrared(VIS-NIR)refl ectance of the HGMs/TiO2 composite hollow spheres were characterized.The VIS-NIR reflectance of the HGMs/TiO2 composite hollow spheres increased by more than 30%compared to raw HGMs.The thermal conductivity of the particles is 0.058 W/(m K).The result indicates that the VIS-NIR reflectance of the composite hollow spheres is strongly influenced by the coating of TiO2.The composite hollow spheres were used as the main functional filler to prepare the organic-inorganic composite coatings.The glass substrates coated by the organic-inorganic coatings had lower thermal conductivity and higher near infrared reflectivity.Therefore,the HGMs/TiO2 composite hollow spheres can reflect most of the solar energy and effectively keep out the heat as a thermal insulation coating for energy-saving constructions.
文摘Core-shell structured SiO2/poly（N-isopropylacrylamide） （SiO2/PNIPAM） microspheres were successfully fabricated through hydrolysis and condensation reaction of tertraethyl orthosilicate （TEOS） on the surface of PNIPAM template at 50 ~C. The PNIPAM template can be easily removed by water at room temperature so that SiO2 hollow microspheres were finally obtained. The transmission electron microscope and scanning electron microscope observations indicated that SiO2 hollow microspheres with an average diameter of 150 nm can be formed only if there are enough concentration of PNIPAM and TEOS, and the hy- drolysis time of TEOS. FTIR analysis showed that part of PNIPAM remained on the wall of SiO2 because of the strong interaction between PNIPAM and silica. This work provides a clean and efficient way to prepare hollow microspheres.
基金Project(50574063)supported by the National Natural Science Foundation of China
文摘In order to improve the lower practical capacity and bad cyclability of crystalline V2O5（c-V2O5）,the vanadium oxide（V2O5） and polypyrrole（PPy） hybrid with hollow-spherical（HS） structure was studied.HS nanocomposite comprised of conductive polypyrrole and vanadium pentoxide（PPy/V2O5） was synthesized by polymerization of pyrrole monomer（Py） in the hollow-microspherical V2O5 host.This novel hybrid was characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM） and tested as the cathode material for lithium-ion batteries（LIB） by galvanostatic cell cycling and electrochemical impedance spectroscopy（EIS）.The hollow-spherical polypyrrole/vanadium oxide（HS-PPy/V2O5） composites,in which PPy molecules are intercalated between the layers of V2O5,exhibit slight reduced capacity and substantially improve cyclability and electrochemical activity compared with the pure HS-V2O5.
基金This work was supported by the National Natural Science Foundation of China(Nos.21871005 and 22171005)the University Synergy Innovation Program of Anhui Province(Nos.GXXT-2020-005,GXXT-2021-012,and GXXT-2021-013)Open project of Shanghai Institute of Technical Physics(No.IIMOKFJJ-19-09).
文摘Recently,rechargeable zinc-ion batteries have been considered as the future development direction of large-scale energy storage due to their low price,safety,environmental friendliness,and excellent electrochemical performance.However,highcapacity,long-cycle stable cathode materials that can meet the demand are still to be developed.Herein,the hollow mesoporous ZnMn2O4/C microsphere cathode material with carbon nanotubes embedded in the shell was prepared by spray pyrolysis for the first time.Its capacity remained at 209.71 mAh·g−1 after 150 cycles at a rate of 0.5 A·g−1,and still maintained a specific capacity of 100.06 mAh·g−1 at a rate of 1 A·g−1 after 1,000 cycles.The outstanding performance is attributed to the hollow structure that can effectively buffer large volume changes caused by ion intercalation and deintercalation,excellent porosity,cationic defects,and high electrical conductivity of carbon nanotubes and its strong adsorption to ZnMn2O4 nanoparticles.
