Metal(oxide)-zeolite bifunctional catalysts have been the subject of considerable attention from researchers in both academic and industry,due to their superior activity and stability in various heterogeneous catalyti...Metal(oxide)-zeolite bifunctional catalysts have been the subject of considerable attention from researchers in both academic and industry,due to their superior activity and stability in various heterogeneous catalytic processes[1–3].Based on the different metal loading sites,these bifunctional catalysts can be categorized as follows:(a)metal species loaded on the outer surface of zeolite crystals,(b)metal species encapsulated within the channels or cavities of zeolites,and(c)metal species incorporated into the zeolite framework(Fig.1).Metal species in type(b)and(c)samples are stabilized by the zeolite frameworks,resulting in excellent thermal and hydrothermal stability during catalytic reactions,especially under harsh conditions,as well as unique shape-selectivity.However,the complex synthesis procedures make large-scale preparation of these catalysts impractical.In contrast,a type(a)sample can be achieved via the simple impregnation;nevertheless,migration of metal species and their aggregation into larger particles often occur during the calcination and reduction processes.展开更多
Mesoporous semiconducting metal oxides(SMOs)heterojunctions are appealing sensors for gas detecting.However,due to the different hydrolysis and condensation mechanism of every metal precursor and the contradiction bet...Mesoporous semiconducting metal oxides(SMOs)heterojunctions are appealing sensors for gas detecting.However,due to the different hydrolysis and condensation mechanism of every metal precursor and the contradiction between high crystallinity and high surface area,the synthesis of mesoporous SMOs heterojunctions with highly o rdered mesostructures,highly crystallized frameworks,and high surface area remains a huge challenge.In this work,we develop a novel"acid-base pair"adjusted solvent evaporation induced self-assembly(EISA)strategy to prepare highly crystallized ordered mesoporous TiO2/WO3(OM-TiO2/WO3)heterojunctions.The WCl6 and titanium isopropoxide(TIPO)are used as the precursors,respectively,which function as the"acid-base pair",enabling the coassembly with the structure directing agent(PEO-b-PS)into highly ordered meso structures.In addition,PEO-b-PS can be converted to rigid carbon which can protect the meso structures from collapse during the crystallization process.The resultant OM-TiO2/WO3 heterojunctions possess primitive cubic mesostructures,large pore size(~21.1 nm),highly crystalline frameworks and surface area(~98 m2/g).As a sensor for acetone,the obtained OM-TiO2/WO3 show excellent re sponse/recovery perfo rmance(3 s/5 s),good linear dependence,repeatability,selectivity,and long-term stability(35 days).展开更多
Cities rely on massive amounts of physical,chemical,and biological resources to support their growth and metabolism.These‘metabolic inputs’are accumulated in cities to form material stocks in buildings,infrastructur...Cities rely on massive amounts of physical,chemical,and biological resources to support their growth and metabolism.These‘metabolic inputs’are accumulated in cities to form material stocks in buildings,infrastructures,transportation facilities,and household appliances.This study takes China’s urbanization as an example to illustrate the characteristics of material stock changes in developing countries and compare them with those in developed countries.Results show that(1)material stocks have been growing in China,but have saturated in developed countries,and(2)the major components of urban metabolism are construction and industrial materials(e.g.,steel)in developing countries but biomass(e.g.,food)in developed countries.The changes in the magnitude and types of material stocks can not only measure urban development but also directly link city and its residents,offering advantages in representing urbanization over the existing indices such as population,land use,or gross domestic product(GDP).Given the new insights provided by material stock,we recommend to embrace it as a critical index of urbanization for guiding urban planning and policy-making.展开更多
In this work,as a new type of oil-based additive,a phosphate mixture of(Sr_(0.9)Ca_(0.1))_(3)(PO_(4))_(2)and Sr_(3)(PO_(4))_(2)(SrP)with a flower-like structure was synthesized.Compared with pure poly-α-olefin-8(PAO8...In this work,as a new type of oil-based additive,a phosphate mixture of(Sr_(0.9)Ca_(0.1))_(3)(PO_(4))_(2)and Sr_(3)(PO_(4))_(2)(SrP)with a flower-like structure was synthesized.Compared with pure poly-α-olefin-8(PAO8),when a titanium alloy is lubricated,the use of 20 wt%SrP for lubrication can reduce the coefficient of friction(COF)by 69.89%and the wear rate(WR)by 99.86%.The extraordinary tribological performance was attributed to the deposition of a layer of SrP on the surface of the titanium alloy.On the one hand,the deposition layer formed by SrP can prevent direct contact between friction pairs,protect the surface of the titanium alloy,and prevent adhesion wear of the titanium alloy.On the other hand,the low-shear interlayer sliding of SrP nanosheets inside the deposition layer was beneficial for friction reduction.X-ray photoelectron spectroscopy(XPS)confirmed that after frictional sliding,the active group phosphate in SrP was activated,and other metals were oxidized to produce a series of oxides.In addition,phosphate can form P‒O‒Ti bonds with titanium at the interface,which is the key to SrP deposition and adsorption on the surface of titanium alloys.The SrP additive not only exhibited excellent performance in lubricating titanium alloy discs but also stainless steel 304,42CrMo,and tin bronze.After lubrication with 20 wt%SrP additive,the wear tracks of stainless steel 304 and 42CrMo were not detected,and WR of tin bronze decreased by 92%.An interface lubrication mechanism has been proposed that may be beneficial for the design and application of new lubricating materials.展开更多
Natural esters exhibit excellent flame retardant and biodegradability,which help minimize power accidents and reduce environmental impact.These qualities make natural esters a promising alternative to conventional tra...Natural esters exhibit excellent flame retardant and biodegradability,which help minimize power accidents and reduce environmental impact.These qualities make natural esters a promising alternative to conventional transformer insulating oils.However,the practical applications of natural esters in power equipment have been significantly restricted by their inherent limitations,including elevated viscosity,high dielectric loss,and poor oxidative stability.Nano-modification technologies present a novel methodological approach to solve these inherent constraints.A systematic analysis of the latest research developments in nano-modified natural ester transformer oils is provided in this review.The properties of various natural esters are examined,and their suitability as base fluids is evaluated,while the modification effects and mechanisms of typical nano-additives are comprehensively reviewed.The key role of nano-modification technology in improving the overall performance of natural esters is elucidated through detailed analysis of how nanoparticles influence physical properties,dielectric properties,and oxidative stability.In addition,the practical challenges facing nano-modification technology are addressed,providing valuable theoretical guidance for future developments in this field.展开更多
Friction and wear are ubiquitous,from nano-electro-mechanical systems in biomedicine to large-scale integrated electric propulsion in aircraft carriers.Applications of nanomaterials as lubricating oil additives have a...Friction and wear are ubiquitous,from nano-electro-mechanical systems in biomedicine to large-scale integrated electric propulsion in aircraft carriers.Applications of nanomaterials as lubricating oil additives have achieved great advances,which are of great significance to control friction and wear.This review focuses on the applications of nanomaterials in lubricating oil and comprehensively compares their tribological characteristics as lubricating oil additives.Statistical analysis of tribology data is provided and discussed accordingly;moreover,the interaction between nanomaterials and sliding surface,lubricating oil,other additives,and synergistic lubrication in nanocomposites are systematically elaborated.Finally,suggestions for future research on nanomaterials as lubricating oil additives are proposed.Hence,this review will promote a better fundamental understanding of nanomaterials for lubricating oil application and help to achieve the superior design of nanoadditives with outstanding tribological performances.展开更多
In this work,the advantage of Coulomb repulsion in the intermolecular forces experienced by molecules on the solid–liquid nanosized contact interface is taken,and the superior friction-reducing property of Cu_(3)(PO_...In this work,the advantage of Coulomb repulsion in the intermolecular forces experienced by molecules on the solid–liquid nanosized contact interface is taken,and the superior friction-reducing property of Cu_(3)(PO_(4))2·3H_(2)O(CuP)oil-based additives has been confirmed for titanium alloy.Three-dimensional(3D)CuP nanoflowers(CuP-Fs)with a strong capillary absorption effect are prepared to achieve the homogeneous mixing of solid CuP and lubricating oil.Lubrication by CuP-Fs additives for titanium alloy,friction coefficient(COF)can be reduced by 73.68%,and wear rate(WR)reduced by 99.69%.It is demonstrated that the extraordinary friction-reducing property is due to the repulsive solid–liquid interface with low viscous shear force originating from Coulomb repulsion between polar water molecules in CuP and non-polar oil molecules.However,any steric hindrance or connection between this repulsive solid–liquid interface will trigger the adhesion and increase the viscous shear force,for example,dispersant,hydrogen bondings,and shaky adsorbed water molecules.Besides,the lamellar thickness of CuP and the molecular size of lubricant both have a great influence on tribological properties.Here the lubrication mechanism based on interface Coulomb repulsion is proposed that may help broaden the scope of the exploration in low-friction nanomaterial design and new lubricant systems.展开更多
基金financially supported by the National Key R&D Program of China(2024YFE0101100)the National Natural Science Foundation of China(22475112,22305132,22305155)+1 种基金the China Postdoctoral Science Foundation(2023M732323)the Postdoctoral Fellowship Program of CPSF(GZC20231679).
文摘Metal(oxide)-zeolite bifunctional catalysts have been the subject of considerable attention from researchers in both academic and industry,due to their superior activity and stability in various heterogeneous catalytic processes[1–3].Based on the different metal loading sites,these bifunctional catalysts can be categorized as follows:(a)metal species loaded on the outer surface of zeolite crystals,(b)metal species encapsulated within the channels or cavities of zeolites,and(c)metal species incorporated into the zeolite framework(Fig.1).Metal species in type(b)and(c)samples are stabilized by the zeolite frameworks,resulting in excellent thermal and hydrothermal stability during catalytic reactions,especially under harsh conditions,as well as unique shape-selectivity.However,the complex synthesis procedures make large-scale preparation of these catalysts impractical.In contrast,a type(a)sample can be achieved via the simple impregnation;nevertheless,migration of metal species and their aggregation into larger particles often occur during the calcination and reduction processes.
基金supported by the National Natural Science Foundation of China(Nos.51822202 and 51772050)China Postdoctoral Science Foundation(No.2019M651342)+2 种基金Shanghai Rising-Star Program(No.18QA1400100)Youth Top-notch Talent Support Program of Shanghai,the Shanghai Committee of Science and Technology,China(No.19520713200)DHU Distinguished Young Professor Program and Fundamental Research Funds for the Central Universities。
文摘Mesoporous semiconducting metal oxides(SMOs)heterojunctions are appealing sensors for gas detecting.However,due to the different hydrolysis and condensation mechanism of every metal precursor and the contradiction between high crystallinity and high surface area,the synthesis of mesoporous SMOs heterojunctions with highly o rdered mesostructures,highly crystallized frameworks,and high surface area remains a huge challenge.In this work,we develop a novel"acid-base pair"adjusted solvent evaporation induced self-assembly(EISA)strategy to prepare highly crystallized ordered mesoporous TiO2/WO3(OM-TiO2/WO3)heterojunctions.The WCl6 and titanium isopropoxide(TIPO)are used as the precursors,respectively,which function as the"acid-base pair",enabling the coassembly with the structure directing agent(PEO-b-PS)into highly ordered meso structures.In addition,PEO-b-PS can be converted to rigid carbon which can protect the meso structures from collapse during the crystallization process.The resultant OM-TiO2/WO3 heterojunctions possess primitive cubic mesostructures,large pore size(~21.1 nm),highly crystalline frameworks and surface area(~98 m2/g).As a sensor for acetone,the obtained OM-TiO2/WO3 show excellent re sponse/recovery perfo rmance(3 s/5 s),good linear dependence,repeatability,selectivity,and long-term stability(35 days).
基金supported by the National Key Research and Development Program of Ministry of Science and Technology of China(2017YFC0505703)the National Natural Science Foundation of China(41801222)+1 种基金the Key Program of Frontier Science of the Chinese Academy of Sciences(QYZDB-SSW-DQC012)the Fujian Foreign Cooperation Funding(2019I0031).
文摘Cities rely on massive amounts of physical,chemical,and biological resources to support their growth and metabolism.These‘metabolic inputs’are accumulated in cities to form material stocks in buildings,infrastructures,transportation facilities,and household appliances.This study takes China’s urbanization as an example to illustrate the characteristics of material stock changes in developing countries and compare them with those in developed countries.Results show that(1)material stocks have been growing in China,but have saturated in developed countries,and(2)the major components of urban metabolism are construction and industrial materials(e.g.,steel)in developing countries but biomass(e.g.,food)in developed countries.The changes in the magnitude and types of material stocks can not only measure urban development but also directly link city and its residents,offering advantages in representing urbanization over the existing indices such as population,land use,or gross domestic product(GDP).Given the new insights provided by material stock,we recommend to embrace it as a critical index of urbanization for guiding urban planning and policy-making.
基金supported by the Major Program(D)of Hubei Province(2023BAA003)the National Natural Science Foundation of China(52205213)Shanghai Sailing Program(24YF2744900).
文摘In this work,as a new type of oil-based additive,a phosphate mixture of(Sr_(0.9)Ca_(0.1))_(3)(PO_(4))_(2)and Sr_(3)(PO_(4))_(2)(SrP)with a flower-like structure was synthesized.Compared with pure poly-α-olefin-8(PAO8),when a titanium alloy is lubricated,the use of 20 wt%SrP for lubrication can reduce the coefficient of friction(COF)by 69.89%and the wear rate(WR)by 99.86%.The extraordinary tribological performance was attributed to the deposition of a layer of SrP on the surface of the titanium alloy.On the one hand,the deposition layer formed by SrP can prevent direct contact between friction pairs,protect the surface of the titanium alloy,and prevent adhesion wear of the titanium alloy.On the other hand,the low-shear interlayer sliding of SrP nanosheets inside the deposition layer was beneficial for friction reduction.X-ray photoelectron spectroscopy(XPS)confirmed that after frictional sliding,the active group phosphate in SrP was activated,and other metals were oxidized to produce a series of oxides.In addition,phosphate can form P‒O‒Ti bonds with titanium at the interface,which is the key to SrP deposition and adsorption on the surface of titanium alloys.The SrP additive not only exhibited excellent performance in lubricating titanium alloy discs but also stainless steel 304,42CrMo,and tin bronze.After lubrication with 20 wt%SrP additive,the wear tracks of stainless steel 304 and 42CrMo were not detected,and WR of tin bronze decreased by 92%.An interface lubrication mechanism has been proposed that may be beneficial for the design and application of new lubricating materials.
基金supported by the Shanghai Sailing Program(Grant No.24YF2744900)Research and Innovation Project of Shanghai Municipal Education Commission(Grant No.2023ZKZD54)+1 种基金Industrial Collaborative Innovation Project of Shanghai(Grant Nos.2021-cyxt1-kj37 and XTCX-KJ-2022-70)Technical Standard Project of Shanghai(Grant No.23DZ2201100).
文摘Natural esters exhibit excellent flame retardant and biodegradability,which help minimize power accidents and reduce environmental impact.These qualities make natural esters a promising alternative to conventional transformer insulating oils.However,the practical applications of natural esters in power equipment have been significantly restricted by their inherent limitations,including elevated viscosity,high dielectric loss,and poor oxidative stability.Nano-modification technologies present a novel methodological approach to solve these inherent constraints.A systematic analysis of the latest research developments in nano-modified natural ester transformer oils is provided in this review.The properties of various natural esters are examined,and their suitability as base fluids is evaluated,while the modification effects and mechanisms of typical nano-additives are comprehensively reviewed.The key role of nano-modification technology in improving the overall performance of natural esters is elucidated through detailed analysis of how nanoparticles influence physical properties,dielectric properties,and oxidative stability.In addition,the practical challenges facing nano-modification technology are addressed,providing valuable theoretical guidance for future developments in this field.
基金supported by the National Key R&D Program of China(No.2018YFB2000301)the National Natural Science Foundation of China(No.51905385).
文摘Friction and wear are ubiquitous,from nano-electro-mechanical systems in biomedicine to large-scale integrated electric propulsion in aircraft carriers.Applications of nanomaterials as lubricating oil additives have achieved great advances,which are of great significance to control friction and wear.This review focuses on the applications of nanomaterials in lubricating oil and comprehensively compares their tribological characteristics as lubricating oil additives.Statistical analysis of tribology data is provided and discussed accordingly;moreover,the interaction between nanomaterials and sliding surface,lubricating oil,other additives,and synergistic lubrication in nanocomposites are systematically elaborated.Finally,suggestions for future research on nanomaterials as lubricating oil additives are proposed.Hence,this review will promote a better fundamental understanding of nanomaterials for lubricating oil application and help to achieve the superior design of nanoadditives with outstanding tribological performances.
基金the National Natural Science Foundation of China(Nos.51975421,52075405,and 51975420)Hubei Longzhong Laboratory Independent Innovation Research Project(No.2022ZZ-05).
文摘In this work,the advantage of Coulomb repulsion in the intermolecular forces experienced by molecules on the solid–liquid nanosized contact interface is taken,and the superior friction-reducing property of Cu_(3)(PO_(4))2·3H_(2)O(CuP)oil-based additives has been confirmed for titanium alloy.Three-dimensional(3D)CuP nanoflowers(CuP-Fs)with a strong capillary absorption effect are prepared to achieve the homogeneous mixing of solid CuP and lubricating oil.Lubrication by CuP-Fs additives for titanium alloy,friction coefficient(COF)can be reduced by 73.68%,and wear rate(WR)reduced by 99.69%.It is demonstrated that the extraordinary friction-reducing property is due to the repulsive solid–liquid interface with low viscous shear force originating from Coulomb repulsion between polar water molecules in CuP and non-polar oil molecules.However,any steric hindrance or connection between this repulsive solid–liquid interface will trigger the adhesion and increase the viscous shear force,for example,dispersant,hydrogen bondings,and shaky adsorbed water molecules.Besides,the lamellar thickness of CuP and the molecular size of lubricant both have a great influence on tribological properties.Here the lubrication mechanism based on interface Coulomb repulsion is proposed that may help broaden the scope of the exploration in low-friction nanomaterial design and new lubricant systems.
