Mesoporous framework supported metal nanoparticle catalyst represents a promising material platform for creating multiple active sites that drive tandem reactions. In this study, we demonstrate a novel catalyst design...Mesoporous framework supported metal nanoparticle catalyst represents a promising material platform for creating multiple active sites that drive tandem reactions. In this study, we demonstrate a novel catalyst design that involves the encapsulation of CuNi alloy nanoparticles within mesoporous silicon carbide nanofibers (mSiC_(f)) to achieve efficient tandem conversion of furfural (FFA) into 2-(isopropoxymethyl)furan (IPF). The unique one-dimensional (1D) mesoporous structure of mSiC_(f), coupled with abundant oxygen-containing groups, offers a favorable surface microenvironment for the stabilization of bimetallic CuNi active sites. Through carefully optimizing metal to acid sites, we have developed a catalyst containing a total mass ratio of 20 % Cu and Ni, which exhibits a remarkable performance with complete FFA conversion and 92 % IPF selectivity in 4 h. In-depth mechanistic investigations have revealed that the superior activity of this catalyst is attributed to a tandem reaction mechanism. Initially, FFA is hydrogenated at the dual metal active sites to produce furfuryl alcohol (FOL) as an intermediate, which is subsequently etherified at the acid sites with suitable species and strengths on the mSiC_(f) supports. Additionally, the robust 1D mSiC_(f) framework effectively protects the metal sites from agglomeration, resulting in excellent reusability of the catalyst. This study underscores the potential of mesoporous silicon carbide-supported bimetallic active sites for achieving enhanced tandem catalytic functionality.展开更多
Photocatalysis and Fenton process are two primary and promising advanced oxidation processes to degrade organic pollutants.However,the practical applications of single photocatalysis and Fenton process are still limit...Photocatalysis and Fenton process are two primary and promising advanced oxidation processes to degrade organic pollutants.However,the practical applications of single photocatalysis and Fenton process are still limited.Introducing one of them into another to form a combined photocatalytic Fentonlike system has shown great potential but still faces challenges in designing a well-tailored catalyst.Herein,a confined photocatalytic Fenton-like micro-reactor catalyst with a movable Fe_(3) O_(4) core and a mesoporous TiO_(2) shell has been constructed via a successive Stober coating strategy,followed by an ultrasound assisted etching method.The resulting micro-reactor possesses well-defined yolk-shell structures with unifo rm mesopores(~4 nm),a large Brunauer-Emmett-Teller(BET) surface area(~166.7 m^(2)/g),a high pore volume(~0.56 cm^(3)/g) and a strong magnetization(~51 emu/g),as well as tunable reactor sizes(20-90 nm).When evaluated for degrading bisphenol A under solar light in the presence of peroxymo no sulfate,the micro-reactor exhibits a superior catalytic degradation perfo rmance with a high magnetic separation efficiency and an excellent recycle ability.The outstanding performance can be attributed to its unique textual structure,which leads to a great syne rgistic effect from the photocatalytic and Fenton-like process.This study gives an important insight into the design and synthesis of an advanced micro-reactor for a combined advanced oxidation processes(AOPs).展开更多
Electromagnetic wave absorber is critical for reducing increasingly serious electromagnetic wave pollu-tion,however,the development of lightweight and broadband microwave absorbers remains a pressing challenge.We repo...Electromagnetic wave absorber is critical for reducing increasingly serious electromagnetic wave pollu-tion,however,the development of lightweight and broadband microwave absorbers remains a pressing challenge.We report here the rational design and synthesis of N-doped Ni@SiO_(2)/graphene composite con-structed from 3D interconnected porous graphene network and Ni@SiO_(2) core-shell architecture,which fulfills lightweight and broadband requirements while exhibiting highly efficient electromagnetic wave absorption.The porous graphene network,functioning both as lightweight support and dielectric medi-ator,was synthesized via NaCl template-assisted high-temperature calcination method.Upon uniformly attached with core-shell Ni@SiO_(2) on the surface,the resulting abundant heterogeneous interfaces con-structed by graphene-Ni and Ni-SiO_(2) strongly reinforce polarization loss.The presence of low dielectric SiO_(2) allows facile tuning of the complex permittivity of ternary composite by adjusting coating thick-ness to balance the attenuation ability and impedance matching.Moreover,further N-doping of graphene assists in the optimization of dielectric loss ability.Taking account of the advantages arising from the porous hierarchical architecture,multiple absorption centers and diverse interfaces,the lightweight com-posite exhibits an ultra-strong reflection loss(RL)value of-71.13 dB at 13.76 GHz with a thickness of 2.46 mm and broad effective absorption bandwidth of 7.04 GHz at a low filler content of 15 wt.%.More importantly,the effective absorption range covers 13.28 GHz(4.72-18 GHz)with the optimized thickness of 1.6-5 mm,representing 83%of the whole range of frequencies.Our results demonstrate that the novel 3D porous N-doped Ni@SiO_(2)/graphene network with hierarchical architecture is a promising candidate for high-performance electromagnetic wave absorption.展开更多
Cu@Ag/Bi2Te3 nanocomposites were prepared for the first time by ultrasonic dispersion-rapid freezedrying method combined with spark plasma sintering(SPS).By changing the content of Cu@Ag nanoparticle,we could modulate...Cu@Ag/Bi2Te3 nanocomposites were prepared for the first time by ultrasonic dispersion-rapid freezedrying method combined with spark plasma sintering(SPS).By changing the content of Cu@Ag nanoparticle,we could modulate the temperature dependent thermoelectric properties.The highest ZT value can be obtained at 450 K for 1 vol%Cu@Ag/Bi2Te3,which is benefited from the decoupling of electrical and thermal properties.With the increase of electrical conductivity,the absolute value of Seebeck coefficient lifts while the thermal conductivity declines.Meanwhile,the average ZT value between 300 K and 475 K was 0.61 for 1 vol%Cu@Ag/Bi2Te3,which is much higher than that of pristine Bi2 Te3.Therefore,the decoupling effect of Cu@Ag nanoparticles incorporation could be a promising method to broaden the application of Bi2Te3 based thermoelectric materials.展开更多
Nanocomposites constructed by combining mesoporous metal oxides and graphene have received tremendous attention in wide fields of catalysis,energy storage and conversion,gas sensing and so on.Herein,we present a facil...Nanocomposites constructed by combining mesoporous metal oxides and graphene have received tremendous attention in wide fields of catalysis,energy storage and conversion,gas sensing and so on.Herein,we present a facile interface-induced co-assembly process to synthesize the mesoporous W03@graphene aerogel nanocomposites(denoted as mW03@GA),in which graphene aerogel(GA) was used as a macroporous substrate,mesoporous W03 was uniformly coated on both sides of graphene sheets through a solvent evaporation-induced self-assembly(EISA) strategy using diblock copolymer poly(ethylene oxide)-b-polystyrene(PEO-b-PS) as a template.The resultant mW03@GA nanocomposites possess well-interconnected macroporous graphene networks covered by mesoporous W03 layer with a uniform pore size of 19 nm,high surface area of 167 m^2/g and large pore volume of 0.26 cm^3/g.The gas sensing performance of mW03@GA nanocomposites toward acetone and other gases was studied,showing a high selectivity and great response to acetone at low temperature of 150℃,which could be developed as a promising candidate as novel sensors for VOCs detection.展开更多
Due to a combination of outstanding properties including high melting point,high density,low thermal expansion coefficient,low saturated vapor pressure and excellent thermal conductivity,tungsten(W)parts have been wid...Due to a combination of outstanding properties including high melting point,high density,low thermal expansion coefficient,low saturated vapor pressure and excellent thermal conductivity,tungsten(W)parts have been widely used as electrodes,heating elements,anti-scatter grids for Computed Tomography(CT)equipment,rocket nozzles and divertor materials for nuclear fusion[1].展开更多
Thanks to their tunable luminescence,narrow emission range,and superior color fidelity,perovskite quantum dots(PeQDs)are widely considered as promising materials for next-generation backlight displays.However,the susc...Thanks to their tunable luminescence,narrow emission range,and superior color fidelity,perovskite quantum dots(PeQDs)are widely considered as promising materials for next-generation backlight displays.However,the susceptibility to degradation and failure when exposed to ambient environment significantly hampers their widespread applications.Herein,we reported an effective strategy to encapsulate CsPbBr_(3)nanocrystals into robust KBr matrix via cold sintering process at 120℃.The well prepared translucent CsPbBr_(3)@KBr ceramic displays a narrow green photoluminescence(with a fullwidth at half-maximum of~22 nm)and an quantum yield of 73.6%with remarkable thermal stability.By incorporating red emitting K_(2)SiF_(4):Mn^(4+)phosphor into the KBr matrix,the color gamut of the constructed white LED improves to 118%of the National Television System Committee(NTSC)standard,suggesting that the thermally robust and narrow-band green emitter holds significant promise for widecolor-gamut liquid crystal displays.展开更多
Cold-sintered ceramics typically exhibit inferior mechanical properties compared to high-temperature sintered counterparts.We demonstrate that introducing large internal stress through highly concentrated nanodiamonds...Cold-sintered ceramics typically exhibit inferior mechanical properties compared to high-temperature sintered counterparts.We demonstrate that introducing large internal stress through highly concentrated nanodiamonds(NDs)significantly enhances cold-sintered a-quartz composites to structural ceramic levels.At 500 MPa cold-sintering pressure,uniformly dispersed NDs generate 1.2 GPa local prestress via Young's modulus difference,while pressure-modulated internal stress is evidenced by dielectric property changes.The optimized composite achieves fracture toughness of(3.65±0.21)MPa·m^(1/2)(180%increase)and Vickers hardness of 10.6 GPa(80%increase),matching some hightemperature-sintered ceramics.Toughening arises from prestress-driven crack deflection and crack tip bridging,while hardness enhancement stems from NDs'rigid constraint and high-pressure-induced dislocations in silica matrix.Compressive strength increases by 90%and fatigue life exceeds 1000 cycles,attributed to internal stress-strengthened grain boundaries and improved toughness.This work presents a transformative strategy for developing damage-resistant ceramics,meriting further exploration of scalability and engineering applications.展开更多
The X band(8 GHz-12 GHz)is the electromagnetic wave band emitted by most electronic instruments in our life,which will cause electromagnetic pollution harm to human health.Due to the coexistence of magnetic loss and d...The X band(8 GHz-12 GHz)is the electromagnetic wave band emitted by most electronic instruments in our life,which will cause electromagnetic pollution harm to human health.Due to the coexistence of magnetic loss and dielectric loss,the modified Fe_(3)O_(4)-carbon-based nanomaterial exhibit strong electromagnetic(EM)wave absorptive capacity.However,there is a problem that the effective absorption bandwidth(EAB,the frequency bandwidth of reflection loss is less than-10 dB)of the X band is narrow.Increasing the EAB value of Fe_(3)O_(4)-carbon-based materials is of great significance for reducing electromagnetic pollution.Here,an emulsion-based self-assembly technique and ligand carbonization treatment have been used to construct the Fe_(3)O_(4)@C supraparticles for the evaluation of EM performance.The Fe_(3)O_(4)@C supraparticles exhibit excellent EM absorption properties,which can achieve full coverage of X band from 6.52 GHz to 12.9 GHz at a sample thickness of 3 mm.Besides,the optimum EAB value of Fe_(3)O_(4)@C supraparticles is up to 8.55 GHz from 9 to 18 GHz at a sample thickness of 2.5 mm.The Fe_(3)O_(4)@C supraparticles with superlattice structure will have potential development prospects in the application of broadband absorption.展开更多
A broad tunability of the thermoelectric and mechanical properties of CoSb_(3) has been demonstrated by adjusting the composition with the addition of an increasing number of elements.However,such a strategy may negat...A broad tunability of the thermoelectric and mechanical properties of CoSb_(3) has been demonstrated by adjusting the composition with the addition of an increasing number of elements.However,such a strategy may negatively impact processing repeatability and composition control.In this work,singleelement-filled skutterudite is engineered to have high thermoelectric and mechanical performances.Increased Yb filling fraction is found to increase phonon scattering,whereas cryogenic grinding contributes additional microstructural scattering.A peak zT of 1.55 and an average zT of about 1.09,which is comparable to the reported results of multiple-filled SKDs,are realized by the combination of simple composition and microstructure engineering.Furthermore,the mechanical properties of Yb single-filled CoSb_(3) skutterudite are improved by manipulation of the microstructure through cryogenic grinding.These findings highlight the realistic prospect of producing high-performance thermoelectric materials with reduced compositional complexity.展开更多
Glass with high visible-light transparency is widely considered as the most important optical material,which typically requires a processing temperature higher than 1000℃.Here,we report a translucent aluminosilicate ...Glass with high visible-light transparency is widely considered as the most important optical material,which typically requires a processing temperature higher than 1000℃.Here,we report a translucent aluminosilicate glass that can be prepared by cold sintering process(CSP)at merely 300℃.After eliminating structural pores in hexagonal faujasite(EMT)-type zeolite by heat treatment,the obtained highly active nanoparticles are consolidated to have nearly full density by adding NaOH solution as liquid aids.However,direct densification of EMT powder cannot remove the structural pores of zeolite completely,leading to an opaque compact after the CSP.It is proved that the chemical reaction between the NaOH-and zeolite-derived powders is highly beneficial to dissolution–precipitation process during sintering,leading to the ultra-low activation energy of 27.13 kJ/mol.Although the addition of 5 M NaOH solution greatly promotes the densification via the reaction with aluminosilicate powder,lower or higher concentration of solvent can deteriorate the transmittance of glass.Additionally,the CSP-prepared glass exhibits a Vickers hardness of 4.3 GPa,reaching 60%of the reported value for spark plasma sintering(SPS)-prepared sample.展开更多
The assembly of monomicelles along onedimension(1D)to construct tubular or fibrous mesostructures is greatly desired but still challenging.Herein,we have demonstrated a facile strategy to synthesize 1D bimodal mesopor...The assembly of monomicelles along onedimension(1D)to construct tubular or fibrous mesostructures is greatly desired but still challenging.Herein,we have demonstrated a facile strategy to synthesize 1D bimodal mesoporous metal oxides(e.g.,WO_(3),WO_(3)/Pd,WO_(3)/Pd Cu,TiO_(2),and ZrO_(2))nanofibers(NFs)through assembling the organic-inorganic composite monomicelles in a beam stream generated via an electrospinning technique.This facile and repeatable methodology relies on the preparation of copolymer@metal-complex monomicelles in an anisotropic solution and oriented assembly of them in the beam stream by the selective evaporation of solvent.WO_(3)and its derivatives are chosen as the demo,which show a uniform continuous fibrous structure with dual mesopore sizes(~4.0 and 7.6 nm)and large surface area(~93.1 m^(2)g^(-1)).Benefitting from the unique textual structure,gas sensors made by Pd-decorated mesoporous WO_(3)NFs display outstanding comprehensive sensing performance to ethylbenzene,including a high sensitivity(52.5),an ultralow detection limit(50 ppb),and fast response/recovery kinetics(11/16 s)as well as an outstanding selectivity,which render them promising for rapid environmental monitoring.展开更多
Engineering ceramics with high strength,toughness and electromagnetic interference(EMI)shielding effectiveness(SE)are highly desirable as electromagnetic protecting material in harsh environment.Herein,we show that bo...Engineering ceramics with high strength,toughness and electromagnetic interference(EMI)shielding effectiveness(SE)are highly desirable as electromagnetic protecting material in harsh environment.Herein,we show that both excellent mechanical and EMI shielding performance can be realized in alumina composites embedded with highly aligned reduced graphene oxide(RGO),which are readily prepared via sintering of core-shell structured RGO@Al_(2)O_(3)nanoplates with pressure.Compared to monolithic Al_(2)O_(3),the highly aligned RGO/Al_(2)O_(3)composites show simultaneously improved strength and toughness up to~26.1%and~60.2%,respectively.The steeply rising R-curve behavior proves the better crack tolerance in the highly aligned structure with respect to randomly oriented one.Moreover,the RGO/Al_(2)O_(3)composites also exhibit a high specific EMI SE reaching~34 dB/mm in K band,due to the reflection and highly enhanced absorption after percolation in the out-of-plane direction.These findings provide a novel strategy of designing mechanically reliable engineering ceramic for EMI shielding.展开更多
Correlated phase and microstructural evolution are systematically investigated by electron microscopies in Sr-deficient Sr(Ti,Nb)O_(3)(STNO)thermoelectric ceramics incorporated with different fraction of reduced graph...Correlated phase and microstructural evolution are systematically investigated by electron microscopies in Sr-deficient Sr(Ti,Nb)O_(3)(STNO)thermoelectric ceramics incorporated with different fraction of reduced graphene oxide(RGO).It is found that while no impurity except for very few Ti_(3)O_(5) precipitates are observed in monolithic STNO,the Nb-enriched rutile TiO_(2) appears in RGO/STNO composites.With increasing RGO content,the amount of precipitates increase at first and then decrease when RGO content becomes high,which can be ascribed to the formation of local Magneli phase.In addition,the energy-dispersive X-ray spectra combined with cathodoluminescence characterization indicates that the variation of Sr deficiency experiences the opposite trend with respect to the precipitates content.These findings clearly reveal the unique reducing effect of RGO on the microstructure of doped SrTiO_(3) with Sr deficiency,which can greatly facilitate the design of perovskite based thermoelectric materials of hierarchical structure.展开更多
The use of linear amphiphilic block copolymers as templates is an important method for the preparation of mesoporous materials.However,the obtained assemblies are usually sensitive to synthetic conditions,which impede...The use of linear amphiphilic block copolymers as templates is an important method for the preparation of mesoporous materials.However,the obtained assemblies are usually sensitive to synthetic conditions,which impedes the preparation of such mesoporous materials in certain environments.Herein,we report a universal strategy applying an amphiphilic multiarm triblock copolymer in the preparation of mesoporous metal oxide nanofibers(NFs)using one metal oxide(TiO_(2),ZrO_(2),WO_(3),CeO_(2)),or two(TiO_(2)/WO 3,TiO_(2)/ZrO_(2),TiO_(2)/CeO_(2))and three(TiO_(2)/WO_(3)/CuO)metal oxides as composites.The template consists of modified β-cyclodextrin as the center of the macromolecule which is attached sequentially to a block of polystyrene,poly(acrylic acid),and poly(ethylene oxide).Under electrospinning conditions,stable unimolecular micelles are formed and effectively co-assemble with metal ions to form fibrous nanostructures.As indicated by various characterization methods,the synthesized TiO_(2) and its derived composite NFs maintain a straight and continuous fibrous structure after calcination,and TiO_(2) NFs exhibit uniform mesopores of 10.8 nm in diameter and a large Brunauer-Emmett-Teller surface area of 143.3 m^(2)g^(−1).Benefiting from the characteristic structure,still present after modification,Pt-decorated mesoporous TiO_(2) NFs display excellent ability in the visible-light photocatalytic degradation of tetracycline,which is superior to the commercial P25 catalyst.This study reveals a promising strategy for the preparation of fibrous mesoporous metal oxides.展开更多
As a semiconducting material with relatively low thermal conductivity,MoS_(2) nanoflake has the potential to serve as a modulator for optimizing the performance of thermoelectric(TE)materials.However,the low yield of ...As a semiconducting material with relatively low thermal conductivity,MoS_(2) nanoflake has the potential to serve as a modulator for optimizing the performance of thermoelectric(TE)materials.However,the low yield of MoS_(2) nanoflakes prepared by conventional methods has constrained the development of MoS_(2) optimized TE materials.We propose a mechanical exfoliation method for mass production of MoS_(2) nanoflakes using attrition mill.After mixed with La and Nb co-doped SrTiO_(3)(SLNT)powder,the MoS_(2)/SLNT composites are fabricated by spark plasma sintering.It is found that the heterojunctions formed at MoS_(2)/SLNT interfaces with proper band offset can effectively scatter the low-energy electrons,resulting in enhanced Seebeck coefficient without significantly undermining the electrical conductivity.The power factor of composites is improved when the MoS_(2) content is lower than 1.5 vol%.Meanwhile,the thermal conductivity of composites is significantly decreased due to the phonon scattering induced large thermal resistance at MoS_(2)/SLNT interfaces,which is much higher than that in graphene embedded SrTiO_(3) composites.Consequently,a maximum ZT-0.24 is obtained at 800 K in 1.5 vol%MoS_(2)/SLNT composite,which is~26%higher compared with pristine matrix.This work paves the way for application of TE materials modulated by transition metal dichalcogenides.展开更多
基金supported by the National Natu-ral Science Foundation of China(Nos.52225204,52173233,and 52202085)the Innovation Program of Shanghai Municipal Edu-cation Commission(No.2021-01-07-00-03-E00109)+4 种基金Natural Sci-ence Foundation of Shanghai(No.23ZR1479200)the Shanghai Sci-entific and Technological Innovation Project(No.24520712800)“Shuguang Program”Supported by the Shanghai Education Devel-opment Foundation and Shanghai Municipal Education Commis-sion(No.20SG33)the Fundamental Research Funds for the Central Universities(No.2232024Y-01)the DHU Distinguished Young Professor Program(Nos.LZA2022001and LZB2023002).
文摘Mesoporous framework supported metal nanoparticle catalyst represents a promising material platform for creating multiple active sites that drive tandem reactions. In this study, we demonstrate a novel catalyst design that involves the encapsulation of CuNi alloy nanoparticles within mesoporous silicon carbide nanofibers (mSiC_(f)) to achieve efficient tandem conversion of furfural (FFA) into 2-(isopropoxymethyl)furan (IPF). The unique one-dimensional (1D) mesoporous structure of mSiC_(f), coupled with abundant oxygen-containing groups, offers a favorable surface microenvironment for the stabilization of bimetallic CuNi active sites. Through carefully optimizing metal to acid sites, we have developed a catalyst containing a total mass ratio of 20 % Cu and Ni, which exhibits a remarkable performance with complete FFA conversion and 92 % IPF selectivity in 4 h. In-depth mechanistic investigations have revealed that the superior activity of this catalyst is attributed to a tandem reaction mechanism. Initially, FFA is hydrogenated at the dual metal active sites to produce furfuryl alcohol (FOL) as an intermediate, which is subsequently etherified at the acid sites with suitable species and strengths on the mSiC_(f) supports. Additionally, the robust 1D mSiC_(f) framework effectively protects the metal sites from agglomeration, resulting in excellent reusability of the catalyst. This study underscores the potential of mesoporous silicon carbide-supported bimetallic active sites for achieving enhanced tandem catalytic functionality.
基金supported by the National Natural Science Foundation of China (Nos.5182220221972163 and 51772050)the Fundamental Research Funds for the Central Universities (No. 2232020D-02)+7 种基金Shanghai Sailing Program (No.20YF1400500)Shanghai Natural Science Foundation (No.20ZR1401500)Shanghai Rising-Star Program (No.18QA1400100)Youth Top-notch Talent Support Program of Shanghai,Science and Technology Commission of Shanghai Municipality (No.19520713200)Shanghai Scientific and Technological Innovation Project (No. 19JC1410400)Key Basic Research Program of Science and Technology Commission of Shanghai Municipality (No. 20JC1415300)DHU Distinguished Young Professor ProgramFundamental Research Funds for the Central Universities。
文摘Photocatalysis and Fenton process are two primary and promising advanced oxidation processes to degrade organic pollutants.However,the practical applications of single photocatalysis and Fenton process are still limited.Introducing one of them into another to form a combined photocatalytic Fentonlike system has shown great potential but still faces challenges in designing a well-tailored catalyst.Herein,a confined photocatalytic Fenton-like micro-reactor catalyst with a movable Fe_(3) O_(4) core and a mesoporous TiO_(2) shell has been constructed via a successive Stober coating strategy,followed by an ultrasound assisted etching method.The resulting micro-reactor possesses well-defined yolk-shell structures with unifo rm mesopores(~4 nm),a large Brunauer-Emmett-Teller(BET) surface area(~166.7 m^(2)/g),a high pore volume(~0.56 cm^(3)/g) and a strong magnetization(~51 emu/g),as well as tunable reactor sizes(20-90 nm).When evaluated for degrading bisphenol A under solar light in the presence of peroxymo no sulfate,the micro-reactor exhibits a superior catalytic degradation perfo rmance with a high magnetic separation efficiency and an excellent recycle ability.The outstanding performance can be attributed to its unique textual structure,which leads to a great syne rgistic effect from the photocatalytic and Fenton-like process.This study gives an important insight into the design and synthesis of an advanced micro-reactor for a combined advanced oxidation processes(AOPs).
基金supported by the National Natural Science Foundation of China (Nos.91963204 and 51871053)Shanghai Pujiang Program (No.19PJ1400200)the Fundamental Research Funds for the Central Universities (Nos.2232019G-07 and 2232020A-02)。
文摘Electromagnetic wave absorber is critical for reducing increasingly serious electromagnetic wave pollu-tion,however,the development of lightweight and broadband microwave absorbers remains a pressing challenge.We report here the rational design and synthesis of N-doped Ni@SiO_(2)/graphene composite con-structed from 3D interconnected porous graphene network and Ni@SiO_(2) core-shell architecture,which fulfills lightweight and broadband requirements while exhibiting highly efficient electromagnetic wave absorption.The porous graphene network,functioning both as lightweight support and dielectric medi-ator,was synthesized via NaCl template-assisted high-temperature calcination method.Upon uniformly attached with core-shell Ni@SiO_(2) on the surface,the resulting abundant heterogeneous interfaces con-structed by graphene-Ni and Ni-SiO_(2) strongly reinforce polarization loss.The presence of low dielectric SiO_(2) allows facile tuning of the complex permittivity of ternary composite by adjusting coating thick-ness to balance the attenuation ability and impedance matching.Moreover,further N-doping of graphene assists in the optimization of dielectric loss ability.Taking account of the advantages arising from the porous hierarchical architecture,multiple absorption centers and diverse interfaces,the lightweight com-posite exhibits an ultra-strong reflection loss(RL)value of-71.13 dB at 13.76 GHz with a thickness of 2.46 mm and broad effective absorption bandwidth of 7.04 GHz at a low filler content of 15 wt.%.More importantly,the effective absorption range covers 13.28 GHz(4.72-18 GHz)with the optimized thickness of 1.6-5 mm,representing 83%of the whole range of frequencies.Our results demonstrate that the novel 3D porous N-doped Ni@SiO_(2)/graphene network with hierarchical architecture is a promising candidate for high-performance electromagnetic wave absorption.
基金funded by the National Natural Science Foundation of China(Nos.51774096,51871053)Shanghai Committee of Science and Technology(Nos.16JC1401800,18JC1411200)+1 种基金the Fundamental Research Funds for the Central Universities(No.19D110625)Program of Innovative Research Team in University of Ministry of Education of China(No.IRT16R13)。
文摘Cu@Ag/Bi2Te3 nanocomposites were prepared for the first time by ultrasonic dispersion-rapid freezedrying method combined with spark plasma sintering(SPS).By changing the content of Cu@Ag nanoparticle,we could modulate the temperature dependent thermoelectric properties.The highest ZT value can be obtained at 450 K for 1 vol%Cu@Ag/Bi2Te3,which is benefited from the decoupling of electrical and thermal properties.With the increase of electrical conductivity,the absolute value of Seebeck coefficient lifts while the thermal conductivity declines.Meanwhile,the average ZT value between 300 K and 475 K was 0.61 for 1 vol%Cu@Ag/Bi2Te3,which is much higher than that of pristine Bi2 Te3.Therefore,the decoupling effect of Cu@Ag nanoparticles incorporation could be a promising method to broaden the application of Bi2Te3 based thermoelectric materials.
基金supported by the National Natural Science Foundation of China (Nos.51822202,51772050,51432004 and 51774096)Shanghai Rising-Star Program(No.18QA1400100)+4 种基金Youth Top-notch Talent Support Program of Shanghaithe Innovation Program of Shanghai Municipal Education Commission(No.2017-01-07-00-03-E00025)Shanghai Sailing Program (No.17YF1400400)DHU Distinguished Young Professor ProgramFundamental Research Funds for the Central Universities
文摘Nanocomposites constructed by combining mesoporous metal oxides and graphene have received tremendous attention in wide fields of catalysis,energy storage and conversion,gas sensing and so on.Herein,we present a facile interface-induced co-assembly process to synthesize the mesoporous W03@graphene aerogel nanocomposites(denoted as mW03@GA),in which graphene aerogel(GA) was used as a macroporous substrate,mesoporous W03 was uniformly coated on both sides of graphene sheets through a solvent evaporation-induced self-assembly(EISA) strategy using diblock copolymer poly(ethylene oxide)-b-polystyrene(PEO-b-PS) as a template.The resultant mW03@GA nanocomposites possess well-interconnected macroporous graphene networks covered by mesoporous W03 layer with a uniform pore size of 19 nm,high surface area of 167 m^2/g and large pore volume of 0.26 cm^3/g.The gas sensing performance of mW03@GA nanocomposites toward acetone and other gases was studied,showing a high selectivity and great response to acetone at low temperature of 150℃,which could be developed as a promising candidate as novel sensors for VOCs detection.
基金support from the National Natural Science Foundation of China(Nos.52022072,51972243,92060202 and 51521001)the Research Fund for Central Universities(Nos.2020IVB074 and 2021IVA094)+4 种基金the Creative Research Foundation of the Science and Technology on Thermostructural Composite Materials Laboratory(No.6142911180202)supported by Key R&D Program of Guangdong Province(No.2020B090923002)the China Postdoctoral Science Foundation(No.2021T140140)Guangzhou Project of Science&Technology(Nos.202102020327,202007020008)Guangdong province Science and Technology Plan Projects(No.2019A1515011841)。
文摘Due to a combination of outstanding properties including high melting point,high density,low thermal expansion coefficient,low saturated vapor pressure and excellent thermal conductivity,tungsten(W)parts have been widely used as electrodes,heating elements,anti-scatter grids for Computed Tomography(CT)equipment,rocket nozzles and divertor materials for nuclear fusion[1].
基金supported by the National Natural Science Foundation of China(No.52350443 and No.52122203)the Natural Science Foundation of Shanghai(No.21ZR1400300).
文摘Thanks to their tunable luminescence,narrow emission range,and superior color fidelity,perovskite quantum dots(PeQDs)are widely considered as promising materials for next-generation backlight displays.However,the susceptibility to degradation and failure when exposed to ambient environment significantly hampers their widespread applications.Herein,we reported an effective strategy to encapsulate CsPbBr_(3)nanocrystals into robust KBr matrix via cold sintering process at 120℃.The well prepared translucent CsPbBr_(3)@KBr ceramic displays a narrow green photoluminescence(with a fullwidth at half-maximum of~22 nm)and an quantum yield of 73.6%with remarkable thermal stability.By incorporating red emitting K_(2)SiF_(4):Mn^(4+)phosphor into the KBr matrix,the color gamut of the constructed white LED improves to 118%of the National Television System Committee(NTSC)standard,suggesting that the thermally robust and narrow-band green emitter holds significant promise for widecolor-gamut liquid crystal displays.
基金supported by the National Natural Science Foundation of China(No.52472066,No.52350443 and No.52302061)“Dawn”Program of Shanghai Education Commission(No.24SG32)the Natural Science Foundation of Shanghai(No.21ZR1400300).
文摘Cold-sintered ceramics typically exhibit inferior mechanical properties compared to high-temperature sintered counterparts.We demonstrate that introducing large internal stress through highly concentrated nanodiamonds(NDs)significantly enhances cold-sintered a-quartz composites to structural ceramic levels.At 500 MPa cold-sintering pressure,uniformly dispersed NDs generate 1.2 GPa local prestress via Young's modulus difference,while pressure-modulated internal stress is evidenced by dielectric property changes.The optimized composite achieves fracture toughness of(3.65±0.21)MPa·m^(1/2)(180%increase)and Vickers hardness of 10.6 GPa(80%increase),matching some hightemperature-sintered ceramics.Toughening arises from prestress-driven crack deflection and crack tip bridging,while hardness enhancement stems from NDs'rigid constraint and high-pressure-induced dislocations in silica matrix.Compressive strength increases by 90%and fatigue life exceeds 1000 cycles,attributed to internal stress-strengthened grain boundaries and improved toughness.This work presents a transformative strategy for developing damage-resistant ceramics,meriting further exploration of scalability and engineering applications.
基金support from National Natural Science Foundation of China(No.51702046 and No.91963204)the program for Professor of Special Appointment(Eastern Scholar),State Key Laboratory for Modification of Chemical Fibers and Polymer Materials,Donghua University.
文摘The X band(8 GHz-12 GHz)is the electromagnetic wave band emitted by most electronic instruments in our life,which will cause electromagnetic pollution harm to human health.Due to the coexistence of magnetic loss and dielectric loss,the modified Fe_(3)O_(4)-carbon-based nanomaterial exhibit strong electromagnetic(EM)wave absorptive capacity.However,there is a problem that the effective absorption bandwidth(EAB,the frequency bandwidth of reflection loss is less than-10 dB)of the X band is narrow.Increasing the EAB value of Fe_(3)O_(4)-carbon-based materials is of great significance for reducing electromagnetic pollution.Here,an emulsion-based self-assembly technique and ligand carbonization treatment have been used to construct the Fe_(3)O_(4)@C supraparticles for the evaluation of EM performance.The Fe_(3)O_(4)@C supraparticles exhibit excellent EM absorption properties,which can achieve full coverage of X band from 6.52 GHz to 12.9 GHz at a sample thickness of 3 mm.Besides,the optimum EAB value of Fe_(3)O_(4)@C supraparticles is up to 8.55 GHz from 9 to 18 GHz at a sample thickness of 2.5 mm.The Fe_(3)O_(4)@C supraparticles with superlattice structure will have potential development prospects in the application of broadband absorption.
基金funded by Natural Science Foundation of China(Nos.51774096,51871053)Shanghai Committee of Science and Technology(Nos.16JC1401800,18JC1411200)+1 种基金supported by the NASA Science Missions Directorate under the Radioisotope Power Systems Programsupport from the National Science Foundation(DMREF-1333335 and DMREF-1729487).
文摘A broad tunability of the thermoelectric and mechanical properties of CoSb_(3) has been demonstrated by adjusting the composition with the addition of an increasing number of elements.However,such a strategy may negatively impact processing repeatability and composition control.In this work,singleelement-filled skutterudite is engineered to have high thermoelectric and mechanical performances.Increased Yb filling fraction is found to increase phonon scattering,whereas cryogenic grinding contributes additional microstructural scattering.A peak zT of 1.55 and an average zT of about 1.09,which is comparable to the reported results of multiple-filled SKDs,are realized by the combination of simple composition and microstructure engineering.Furthermore,the mechanical properties of Yb single-filled CoSb_(3) skutterudite are improved by manipulation of the microstructure through cryogenic grinding.These findings highlight the realistic prospect of producing high-performance thermoelectric materials with reduced compositional complexity.
基金financially supported by the National Natural Science Foundation of China(No.52122203).
文摘Glass with high visible-light transparency is widely considered as the most important optical material,which typically requires a processing temperature higher than 1000℃.Here,we report a translucent aluminosilicate glass that can be prepared by cold sintering process(CSP)at merely 300℃.After eliminating structural pores in hexagonal faujasite(EMT)-type zeolite by heat treatment,the obtained highly active nanoparticles are consolidated to have nearly full density by adding NaOH solution as liquid aids.However,direct densification of EMT powder cannot remove the structural pores of zeolite completely,leading to an opaque compact after the CSP.It is proved that the chemical reaction between the NaOH-and zeolite-derived powders is highly beneficial to dissolution–precipitation process during sintering,leading to the ultra-low activation energy of 27.13 kJ/mol.Although the addition of 5 M NaOH solution greatly promotes the densification via the reaction with aluminosilicate powder,lower or higher concentration of solvent can deteriorate the transmittance of glass.Additionally,the CSP-prepared glass exhibits a Vickers hardness of 4.3 GPa,reaching 60%of the reported value for spark plasma sintering(SPS)-prepared sample.
基金supported by the Innovation Program of Shanghai Municipal Education Commission(2021-01-0700-03-E00109)the National Natural Science Foundation of China(51822202 and 51772050)+9 种基金the Science and Technology Commission of Shanghai Municipality(19520713200)Shanghai Sailing Program(20YF1400500)Shanghai Rising-Star Program(18QA1400100)the Key Basic Research Program of Science and Technology Commission of Shanghai Municipality(20JC1415300)Shanghai Natural Science Foundation(20ZR1401500)Shanghai Scientific and Technological Innovation Project(19JC1410400)the Fundamental Research Funds for the Central Universities(2232020D-02)the Youth Top-notch Talent Support Program of ShanghaiDHU Distinguished Young Professor Programfinancial support from Australian Research Council through an ARC Future Fellowship(FT180100387).
文摘The assembly of monomicelles along onedimension(1D)to construct tubular or fibrous mesostructures is greatly desired but still challenging.Herein,we have demonstrated a facile strategy to synthesize 1D bimodal mesoporous metal oxides(e.g.,WO_(3),WO_(3)/Pd,WO_(3)/Pd Cu,TiO_(2),and ZrO_(2))nanofibers(NFs)through assembling the organic-inorganic composite monomicelles in a beam stream generated via an electrospinning technique.This facile and repeatable methodology relies on the preparation of copolymer@metal-complex monomicelles in an anisotropic solution and oriented assembly of them in the beam stream by the selective evaporation of solvent.WO_(3)and its derivatives are chosen as the demo,which show a uniform continuous fibrous structure with dual mesopore sizes(~4.0 and 7.6 nm)and large surface area(~93.1 m^(2)g^(-1)).Benefitting from the unique textual structure,gas sensors made by Pd-decorated mesoporous WO_(3)NFs display outstanding comprehensive sensing performance to ethylbenzene,including a high sensitivity(52.5),an ultralow detection limit(50 ppb),and fast response/recovery kinetics(11/16 s)as well as an outstanding selectivity,which render them promising for rapid environmental monitoring.
基金supported by the National Natural Science Foundation of China(Nos.52122203,51972053,and 9163204)Innovation Program of Shanghai Municipal Education Commission(2023ZKZD43)sponsored by Shanghai Sailing Program(No.22YF1400300).
文摘Engineering ceramics with high strength,toughness and electromagnetic interference(EMI)shielding effectiveness(SE)are highly desirable as electromagnetic protecting material in harsh environment.Herein,we show that both excellent mechanical and EMI shielding performance can be realized in alumina composites embedded with highly aligned reduced graphene oxide(RGO),which are readily prepared via sintering of core-shell structured RGO@Al_(2)O_(3)nanoplates with pressure.Compared to monolithic Al_(2)O_(3),the highly aligned RGO/Al_(2)O_(3)composites show simultaneously improved strength and toughness up to~26.1%and~60.2%,respectively.The steeply rising R-curve behavior proves the better crack tolerance in the highly aligned structure with respect to randomly oriented one.Moreover,the RGO/Al_(2)O_(3)composites also exhibit a high specific EMI SE reaching~34 dB/mm in K band,due to the reflection and highly enhanced absorption after percolation in the out-of-plane direction.These findings provide a novel strategy of designing mechanically reliable engineering ceramic for EMI shielding.
基金supported by the National Natural Science Foundation of China[Grant numbers 51532006,51432004]State Administration of Foreign Experts Affairs of China,111 project[Grant number D16002]the Opening Project of Key Laboratory of Inorganic Functional Materials and Devices,Chinese Academy of Sciences(Grant number KLIFMD201804).
文摘Correlated phase and microstructural evolution are systematically investigated by electron microscopies in Sr-deficient Sr(Ti,Nb)O_(3)(STNO)thermoelectric ceramics incorporated with different fraction of reduced graphene oxide(RGO).It is found that while no impurity except for very few Ti_(3)O_(5) precipitates are observed in monolithic STNO,the Nb-enriched rutile TiO_(2) appears in RGO/STNO composites.With increasing RGO content,the amount of precipitates increase at first and then decrease when RGO content becomes high,which can be ascribed to the formation of local Magneli phase.In addition,the energy-dispersive X-ray spectra combined with cathodoluminescence characterization indicates that the variation of Sr deficiency experiences the opposite trend with respect to the precipitates content.These findings clearly reveal the unique reducing effect of RGO on the microstructure of doped SrTiO_(3) with Sr deficiency,which can greatly facilitate the design of perovskite based thermoelectric materials of hierarchical structure.
基金funded by the National Natural Science Foundation of China(Grants No.51822202,52173233 and 51772050)Innovation Program of Shanghai Municipal Education Commission(Grant No.2021-01-07-00-03-E00109)+8 种基金Science and Technology Commission of Shanghai Municipality(Grant No.19520713200)Shanghai Scientific and Technological Innovation Project(Grant No.19JC1410400)“Shuguang Program”supported by Shanghai Education Development Foundation and Shanghai Municipal Education Commission(Grant No.20SG33)Key Basic Research Program of Science and Technology Com-mission of Shanghai Municipality(Grant No.20JC1415300)DHU Distinguished Young Professor Program and Fundamental Research Funds for the Central Universitiesthe Fundamental Research Funds for the Central Universities(Grant No.2232020D-02)Shanghai Sailing program(Grant No.20YF1400500)Shanghai Natural Science Foundation(Grant No.20ZR1401500)the Opening Project of Key Laboratory of Inorganic Functional Materials and Devices,Chinese Academy of Sciences(KLIFMD202104).
文摘The use of linear amphiphilic block copolymers as templates is an important method for the preparation of mesoporous materials.However,the obtained assemblies are usually sensitive to synthetic conditions,which impedes the preparation of such mesoporous materials in certain environments.Herein,we report a universal strategy applying an amphiphilic multiarm triblock copolymer in the preparation of mesoporous metal oxide nanofibers(NFs)using one metal oxide(TiO_(2),ZrO_(2),WO_(3),CeO_(2)),or two(TiO_(2)/WO 3,TiO_(2)/ZrO_(2),TiO_(2)/CeO_(2))and three(TiO_(2)/WO_(3)/CuO)metal oxides as composites.The template consists of modified β-cyclodextrin as the center of the macromolecule which is attached sequentially to a block of polystyrene,poly(acrylic acid),and poly(ethylene oxide).Under electrospinning conditions,stable unimolecular micelles are formed and effectively co-assemble with metal ions to form fibrous nanostructures.As indicated by various characterization methods,the synthesized TiO_(2) and its derived composite NFs maintain a straight and continuous fibrous structure after calcination,and TiO_(2) NFs exhibit uniform mesopores of 10.8 nm in diameter and a large Brunauer-Emmett-Teller surface area of 143.3 m^(2)g^(−1).Benefiting from the characteristic structure,still present after modification,Pt-decorated mesoporous TiO_(2) NFs display excellent ability in the visible-light photocatalytic degradation of tetracycline,which is superior to the commercial P25 catalyst.This study reveals a promising strategy for the preparation of fibrous mesoporous metal oxides.
基金This work was funded by Natural Science Foundation of Shanghai(No.21 ZR 1400300)Natural Science Foundation of China(No.52174343 and 52122203).
文摘As a semiconducting material with relatively low thermal conductivity,MoS_(2) nanoflake has the potential to serve as a modulator for optimizing the performance of thermoelectric(TE)materials.However,the low yield of MoS_(2) nanoflakes prepared by conventional methods has constrained the development of MoS_(2) optimized TE materials.We propose a mechanical exfoliation method for mass production of MoS_(2) nanoflakes using attrition mill.After mixed with La and Nb co-doped SrTiO_(3)(SLNT)powder,the MoS_(2)/SLNT composites are fabricated by spark plasma sintering.It is found that the heterojunctions formed at MoS_(2)/SLNT interfaces with proper band offset can effectively scatter the low-energy electrons,resulting in enhanced Seebeck coefficient without significantly undermining the electrical conductivity.The power factor of composites is improved when the MoS_(2) content is lower than 1.5 vol%.Meanwhile,the thermal conductivity of composites is significantly decreased due to the phonon scattering induced large thermal resistance at MoS_(2)/SLNT interfaces,which is much higher than that in graphene embedded SrTiO_(3) composites.Consequently,a maximum ZT-0.24 is obtained at 800 K in 1.5 vol%MoS_(2)/SLNT composite,which is~26%higher compared with pristine matrix.This work paves the way for application of TE materials modulated by transition metal dichalcogenides.
