Transition metal dichalcogenides(TMDs)have emerged as promising electrocatalysts for various electrocatalytic processes.Molybdenum disulfide has been widely used,but a single electrocatalyst can hardly be applied to a...Transition metal dichalcogenides(TMDs)have emerged as promising electrocatalysts for various electrocatalytic processes.Molybdenum disulfide has been widely used,but a single electrocatalyst can hardly be applied to all reactions,making it essential to understand the electrochemistry of selected TMDs.Tungsten diselenide(WSe_(2))is reactive in gas evolution processes,similar to molybdenum,yet has received limited attention.This work explores how different exfoliation powers affect WSe_(2)structural configurations and their impact on catalytic performance in hydrogen evolution,oxygen evolution,and capacitive behaviour.The study investigates the structural properties of WSe_(2)nanosheets in both liquid(dispersion)and solid(electrode)phases.Low exfoliation power(90.4 W)contributes to well-defined WSe_(2),while higher power(814 W)leads to an increased number of selenium vacancies.These modifications influence key properties such as thickness,band gaps(1.518 to 1.578 eV),exfoliation yield(0.27 to 0.12 mg mL^(-1)),and oxide content(44.3%to 53.9%),resulting in distinct electrochemical behaviours in different electrolytes.WSe_(2)nanosheets exfoliated at higher power exhibit reduced activity in the hydrogen evolution reaction(HER)due to the loss of W–Se bonds and the formation of an amorphous structure,but they show enhanced oxygen evolution reaction(OER)performance,particularly in alkaline media.Additionally,a higher concentration of selenium vacancies improves capacitive performance in acidic conditions due to proton contributions but are less favourable in neutral and basic electrolytes.This study highlights the importance of exfoliation power in tuning the structural properties of WSe_(2)for specific electrochemical applications,advancing the understanding of its synthesis and performance.展开更多
The preparation of dispersible MFI-type zeolite nanoparticles with open micropores is challenging.Herein,a rapid and effective ultrasound-assisted liquid-phase exfoliation method along with a freezedrying process for ...The preparation of dispersible MFI-type zeolite nanoparticles with open micropores is challenging.Herein,a rapid and effective ultrasound-assisted liquid-phase exfoliation method along with a freezedrying process for redispersion of calcined silicalite-1(S-1)zeolite nanoparticle aggregates using 3-aminopropanol as an exfoliating agent is demonstrated.The exfoliation of S-1 zeolite nanoparticles is characterized by X-ray diffraction,scanning electron microscopy and DLS particle size analysis.The effects of drying methods of as-synthesized zeolite nanoparticle suspension,zeolite contents in frozen nanoparticle suspension,exfoliating agent concentrations,and zeolite doses in ultrasonic suspension on exfoliation efficiency are systematically investigated.It is found that the S-1 zeolite nanoparticle(~70 nm)achieves a yield up to 95%through a 30 min ultrasonic exfoliation in a 3-aminopropanol solution along with a freeze-drying process.The proposed exfoliation mechanism involves two primary stages:vip molecule insertion followed by water expansion,both substantially enhanced by tip sonication.This work offers a comprehensive understanding of the exfoliation process,provides valuable insights into the dispersion of sintered zeolite nanoparticles.展开更多
Ultrathin 2D niobium oxide dichloride(NbOCl_(2))is an emerging member of the 2D ferroelectric material family with extensive potential to provide multifunctionality in electronic devices and nanophotonics elements.It ...Ultrathin 2D niobium oxide dichloride(NbOCl_(2))is an emerging member of the 2D ferroelectric material family with extensive potential to provide multifunctionality in electronic devices and nanophotonics elements.It exhibits negligible interlayer electronic coupling and significant excitonic behavior in the bulk state.Here we substantiate that NbOCl_(2) nanosheets can be exfoliated and effectively size-selected using controlled centrifugation techniques by the liquid phase exfoliation(LPE)method.Spectroscopic measurements displayed that the variations in dispersion were highly dependent on the nanosheet dimensions.The nanosheets seemed to be comparatively defect-free which will be further corroborated by high resolution transmission electron microscopy(HRTEM)and Raman analysis.The size selected nanosheets are unanticipated stable in isopropyl alcohol(IPA),possibly owing to the protective influence of a solvation shell.Additionally,the photothermal conversion response and photothermal stability of nanosized NbOCl_(2) were investigated.Our finding revealed that NbOCl_(2) possesses a robust photothermal agent property,boasting a photothermal conversion efficiency of more than 30%.This underscores its promising potential for various photothermal applications in different fields such as photothermal therapy and thermal energy conversion.展开更多
Exfoliation corrosion(EFC)has rarely been reported for wrought magnesium alloys.Enhanced EFC of the as-extruded Mg–1Li–1Ca alloy was observed after the removal of outermost fine-grained skins.The microstructure and ...Exfoliation corrosion(EFC)has rarely been reported for wrought magnesium alloys.Enhanced EFC of the as-extruded Mg–1Li–1Ca alloy was observed after the removal of outermost fine-grained skins.The microstructure and corrosion products were investigated using optical microscopy,scanning electron microscopy,electron backscattered diffraction,X-ray diffraction,and Fourier transform infrared spectrometry.The corrosion behavior was analyzed using electrochemical polarization,electrochemical impedance spectroscopy,and scanning Kelvin probe techniques.The results indicated that the surface of Mg–1Li–1Ca,with the superficial layer removed,was more susceptible to EFC.A linear correlation between grain boundary density and corrosion resistance was established.Additionally,the influence of factors such as grain size,intermetallic compounds,different alloy surfaces,and corrosion products on EFC were discussed,and the corresponding EFC mechanism was clarified.展开更多
The stacking and aggregation of graphene nanosheets have been obstacles to their application as electrode materials for microelectronic devices.This study deploys a one-step,scalable,facile electrochemical exfoliation...The stacking and aggregation of graphene nanosheets have been obstacles to their application as electrode materials for microelectronic devices.This study deploys a one-step,scalable,facile electrochemical exfoliation technique to fabricate nitrogen(N)and chlorine(Cl)co-doped graphene nanosheets(i.e.,N-Cl-G)via the application of constant voltage on graphite in a mixture of 0.1 mol/L H_(2)SO_(4)and 0.1 mol/L NH_(4)Cl without using dangerous and exhaustive operation.The introduction of Cl(with its large radius)and N,both with high electrical negativity,facilitates the modulation of the electronic structure of graphene and creation of rich structural defects in it.Consequently,in the as-constructed supercapacitors,N-Cl-G exhibits a high specific capacitance of 77 F/g at 0.2 A/g and remarkable cycling stability with 91.7%retention of initial capacitance after 20,000 cycles at 10 A/g.Furthermore,a symmetrical supercapacitor assembled with N-Cl-G as the positive and negative electrodes(denoted as N-Cl-G//N-Cl-G)exhibits an energy density of 3.38 Wh/kg at a power density of 600 W/kg and superior cycling stability with almost no capacitance loss after 5000 cycles at 5 A/g.This study provides a scalable protocol for the facile fabrication of high-performance co-doped graphene as an electrode material candidate for supercapacitors.展开更多
The impact of cooling rate after solution heat treatment on exfoliation corrosion resistance of a Li-containing 7xxx aluminum alloy was investigated by accelerated immersion and electrochemical impedance spectroscopy ...The impact of cooling rate after solution heat treatment on exfoliation corrosion resistance of a Li-containing 7xxx aluminum alloy was investigated by accelerated immersion and electrochemical impedance spectroscopy test,optical microscope,electron backscatter diffraction and scanning transmission electron microscope.With the decrease of cooling rate from 1700℃/s to 4℃/s,exfoliation corrosion resistance of the aged specimens decreases with rating changing from EA to EC and the maximum corrosion depth increasing from about 169.4μm to 632.1μm.Exfoliation corrosion tends to develop along grain boundaries in the specimens with cooling rates higher than about 31℃/s and along both grain boundaries and sub-grain boundaries in the specimens with lower cooling rates.The reason has been discussed based on the changes of the microstructure and microchemistry at grain boundaries and sub-grain boundaries due to slow cooling.展开更多
As one promising carbon-based material,sp^(3)-hybrid carbon nitride has been predicted with various novel physicochemical properties.However,the synthesis of sp^(3)-hybrid carbon nitride is still limited by the nanaos...As one promising carbon-based material,sp^(3)-hybrid carbon nitride has been predicted with various novel physicochemical properties.However,the synthesis of sp^(3)-hybrid carbon nitride is still limited by the nanaoscale,low crystallinity,complex source,and expensive instruments.Herein,we have presented a facile approach to the sp^(3)-hybrid carbon nitride nano/micro-crystals with microwave-assisted confining growth and liquid exfoliation.Actually,the carbon nitride nano/micro-crystals can spontaneously emerge and grow in the microwave-assisted polymerization of citric acid and urea,and the liquid exfoliation can break the bulk disorder polymer to retrieve the highly crystalline carbon nitride nano/micro-crystals.The obtained carbon nitride nano/micro-crystals present superior blue light absorption strength and surprising photoluminescence quantum yields of 57.96% in ethanol and 18.05%in solid state.The experimental characterizations and density functional theory calculations reveal that the interface-trapped localized exciton may contribute to the excellent intrinsic light emission capability of carbon nitride nano/micro-crystals and the interparticle staggered stacking will prevent the aggregation-caused-quenching partially.Finally,the carbon nitride nano/micro-crystals are demonstrated to be potentially useful as the phosphor medium in light-emitting-diode for interrupting blue light-induced eye damage.This work paves new light on the synthesis strategy of sp^(3)-hybrid carbon nitride materials and thus may push forward the development of multiple carbon nitride research.展开更多
With the discovery of graphene,black phosphorus(BP)has been rediscovered as a two-dimensional(2 D)layered material.Since its first preparation in 2014,2 D BP has elicited immense interest,and has exhibited excellent p...With the discovery of graphene,black phosphorus(BP)has been rediscovered as a two-dimensional(2 D)layered material.Since its first preparation in 2014,2 D BP has elicited immense interest,and has exhibited excellent properties,such as distinct pleated structures in layers,adjustable direct bandgap,high carrier mobility,moderate on/off ratio,large specific surface area,and various interesting in-layer anisotropies.However,the realization of these excellent properties depends on the preparation of highquality 2 D BP sheets.Electrochemical exfoliation methods are typically performed under mild conditions,thus,these methods are convenient,controllable,and can produce high-quality 2 D BP sheets.This review summarizes research progress in BP sheets preparation through anodic,cathodic,and electrolyte exfoliation in recent years.Different exfoliating methods affect the quality of 2 D BP sheets.Moreover,possible exfoliating mechanisms and the potential applications of different exfoliating methods are summarized and discussed in detail.Lastly,the shortcomings of existing research on electrochemical exfoliation are presented,and suggestions and prospects for future research on the electrochemical exfoliation of 2 D BP are proposed.展开更多
The exfoliation corrosion （EFC） behavior of 7050-T6 aluminum alloy treated with various quench transfer time after solution heat treatment was investigated by standard EFC immersion tests, strength loss measurements...The exfoliation corrosion （EFC） behavior of 7050-T6 aluminum alloy treated with various quench transfer time after solution heat treatment was investigated by standard EFC immersion tests, strength loss measurements after EFC tests and electrochemical impedance spectroscope （EIS） technique. The results showed that EFC resistance of the alloy decreased with increasing quench transfer time. Backscattered electron scanning electron microscope （SEM） together with transmission electron microscope （TEM） observations revealed that the coverage ratio and microstructure of precipitates at grain boundary area are the most important factors which influence the EFC susceptibility of the alloy, while precipitate-free zone （PFZ） near grain boundary has no or only a minor effect on it. In addition, galvanostatic measurements of the alloy present a good correlation between EFC resistance and transients in potential. The cumulated number of transients in potential can be used to evaluate EFC resistance of the alloy.展开更多
Influence of dual retrogression and re-aging（dual-RRA） temper on microstructure,strength and exfoliation corrosion（EC） behavior of Al-Zn-Mg-Cu alloy was investigated by hardness measurements,tensile properties tes...Influence of dual retrogression and re-aging（dual-RRA） temper on microstructure,strength and exfoliation corrosion（EC） behavior of Al-Zn-Mg-Cu alloy was investigated by hardness measurements,tensile properties tests,exfoliation corrosion tests,transmission electron microscopy（TEM） and scanning electron microscopy（SEM） observation combined energy dispersive X-ray detector（EDX） analysis.Dual-RRA temper maintains the matrix precipitates（MPs） similar to RRA temper,meanwhile obtains coarser and sparser grain boundary precipitates（GBPs） as well as higher Cu and lower Zn content compared with T76 temper.Therefore,dual-RRA temper not only keeps strength equivalent to the RRA temper but also obtains higher EC resistance than T76 temper.展开更多
Exfoliation on as-extruded Mg-1 Li-1 Ca magnesium alloy was investigated after an immersion in 3.5 wt%NaCl aqueous solution for 90, 120 and 150 days through optical microscope, digital camera, scanning electron micros...Exfoliation on as-extruded Mg-1 Li-1 Ca magnesium alloy was investigated after an immersion in 3.5 wt%NaCl aqueous solution for 90, 120 and 150 days through optical microscope, digital camera, scanning electron microscope, electrochemical workstation, scanning Kalvin probe, X-ray diffraction and Fourier transform infrared spectroscope. The results demonstrated that exfoliation corrosion occurred on extruded Mg-1 Li-1 Ca alloy due to elongated microstructure parallel to surface, and delamination of lamellar structure resulted from galvanic effect and wedge effect. Skin layer with fine grains exhibited better corrosion resistance, whereas the interior with coarse grains and the intermetallic compound,Mg2 Ca particles existing in a fibrous structure, dispersed along grain boundaries and extrusion direction in a line. Furthermore, galvanic effect between Mg2 Ca particles and their neighboring a-Mg matrix facilitated dissolution of Mg2 Ca particles and a-Mg matrix; wedge effect was caused by formation of corrosion products. Exfoliation corrosion of extruded Mg-Li-Ca alloys might be a synergic effect of pitting corrosion,filiform corrosion, intergranular corrosion and stress corrosion. Finally, exfoliation corrosion mechanism was proposed.展开更多
Multilayer graphene was prepared by mechanical exfoliation of natural graphite with dioctyl phthalate （DOP） as milling medium without solvent. The obtained mixture could be directly mixed with poly（vinyl chloride）...Multilayer graphene was prepared by mechanical exfoliation of natural graphite with dioctyl phthalate （DOP） as milling medium without solvent. The obtained mixture could be directly mixed with poly（vinyl chloride） （PVC） for melt-forming, with DOP acting as plasticizer and graphene acting as conductive filler for antistatic performance. The composite showed surface resistance of 2.5 ×10 6 Ω/ at 1 wt% carbon additive, significantly lower than approx. 7 wt% of raw graphite required for achieving the same level. This value is low enough for practical antistatic criterion of 3 × 10 8 Ω/ . The effect of filler addition on mechanical performance was minimal, or even beneficial for the milled carbon in contrast to the case of raw graphite.展开更多
Spent cathode carbon(SCC)from aluminum electrolysis is a potential graphite resource.However,full use of the SCC remains a challenge,since it contains many hazardous substances(e.g.,fluoride salts,cyanides),encapsulat...Spent cathode carbon(SCC)from aluminum electrolysis is a potential graphite resource.However,full use of the SCC remains a challenge,since it contains many hazardous substances(e.g.,fluoride salts,cyanides),encapsulated within the thick carbon layers and thus posing serious environmental concerns.This work presents a chemical oxidative exfoliation route to achieve the recycling of SCC and the decontaminated SCC with high-valued graphene oxide(GO)-like carbon structures(SCC-GO)is applied as an excellent adsorbent for organic pollutants.Specifically,after the oxidative exfoliation,the embedded hazardous constituents are fully exposed,facilitating their subsequent removal by aqueous leaching.Moreover,benefiting from the enhanced specific surface areas along with abundant O-containing functional groups,the as-produced SCC-GO,shows an adsorption capacity as high as 347 mg·g^(-1)when considering methylene blue as a pollutant model,which exceeds most of the recently reported carbon-based adsorbents.Our study provides a feasible solution for the efficient recycling of hazardous carbonaceous wastes.展开更多
Flexible yet highly thermoconductive materials are essential for the development of next-generation flexible electronic devices.Herein,we report a bioinspired nanostructured film with the integration of large ductilit...Flexible yet highly thermoconductive materials are essential for the development of next-generation flexible electronic devices.Herein,we report a bioinspired nanostructured film with the integration of large ductility and high thermal conductivity based on self-exfoliated pristine graphene and three-dimensional aramid nanofiber network.A self-grinding strategy to directly exfoliate flake graphite into few-layer and few-defect pristine graphene is successfully developed through mutual shear friction between graphite particles,generating largely enhanced yield and productivity in comparison to normal liquid-based exfoliation strategies,such as ultrasonication,high-shear mixing and ball milling.Inspired by nacre,a new bioinspired layered structural design model containing three-dimensional nanofiber network is proposed and implemented with an interconnected aramid nanofiber network and high-loading graphene nanosheets by a developed continuous assembly strategy of sol-gel-film transformation.It is revealed that the bioinspired film not only exhibits nacre-like ductile deformation behavior by releasing the hidden length of curved aramid nanofibers,but also possesses good thermal transport ability by directionally conducting heat along pristine graphene nanosheets.展开更多
The influence of exfoliation corrosion on the tensile properties of a high strength Al-Zn-Mg-Cu alloy was investigated by ambient temperature tensile testing, optical microscopy, transmission electron microscopy （TEM...The influence of exfoliation corrosion on the tensile properties of a high strength Al-Zn-Mg-Cu alloy was investigated by ambient temperature tensile testing, optical microscopy, transmission electron microscopy （TEM）, scanning electron microscopy （SEM） and electron backscatter diffraction （EBSD）. After exfoliation corrosion immersion, blisters and corrosion pits can be seen on the sheet surface, which lead to loss of materials and notches. A number of intergranular cracks are observed to initiate at the bottom of the corrosion-induced notches and propagate rapidly into the bulk materials during tensile. Consequently, exfoliation corrosion results in significant loss of strength and brittle fracture. EBSD results show that the crack propagation path is primarily along the grain boundaries with misorientation of-45°, and coincidence site lattice （CSL） boundaries are slightly more resistant to crack.展开更多
Synthesis of structurally controlled graphene materials is critical for realizing their practical applications.The electrochemical exfoliation of graphite has emerged as a simple method to produce graphene materials.T...Synthesis of structurally controlled graphene materials is critical for realizing their practical applications.The electrochemical exfoliation of graphite has emerged as a simple method to produce graphene materials.This review examines research progress in the last 5 years,from 2015 to 2019.Graphene material synthesis methods generally have a trade‐off between increasing production yield and achieving better material property control.The synthesis conditions for synthesizing pristine graphene,graphene oxide(GO),and graphene composites are significantly different.Thus,in this review,we first discuss synthesis methods for graphene materials with high C/O ratios from four aspects:graphite electrodes,equipment engineering,electrolytes,and additional reduction methods.Next,we survey synthesis methods for GO and examine how the pretreatment of the graphite electrodes,electrolytes,and operation parameters,such as applied voltages,electrolyte temperatures,and mechanical forces,affect the quality of GO.Further,we summarize electrochemical exfoliation methods used to dope graphene materials,introduce covalent functional groups,incorporate various nanoparticles,and assembly of graphene architectures.For all synthesis methods,we compare the properties of resulting graphene materials such as C/O ratios,lateral size,layer numbers,and quality characterized by Raman spectroscopy.Lastly,we propose our perspectives on further research.We hope this review stimulates more studies to realize the on‐demand production of graphene materials with desired properties using electrochemical exfoliation methods.展开更多
The low cost and facile scalable exfoliation route for two-dimensional hexagonal boron nitride(h-BN)was still indispensable for potential applications.In this work,we presented a convenient and scalable exfoliation fo...The low cost and facile scalable exfoliation route for two-dimensional hexagonal boron nitride(h-BN)was still indispensable for potential applications.In this work,we presented a convenient and scalable exfoliation for few-layer BNNSs.Taking advantage of the advantages of swift heating of microwave and ultra low temperature vaporization of liquid nitrogen,bulk h-BN was high-efficiently exfoliated into fewlayer BNNSs.The as-exfoliated BNNSs had a 2-6 nm thickness and approximately 7.91%yield,exhibiting scalable,facile and environment-friendly features.Furthermo re,the as-exfoliated BNNSs we re applied as additive in oil for reducing friction of oil.The COF of the BNNSs-based grease reduced by 20.10% compared to grease,and the antiwear performance decreased by 55.8% and 45.1% relative to grease and h-BN-based grease.展开更多
Graphene nanosheets(GSs) were prepared from graphite oxide by thermal exfoliation method. The effect of thermal exfoliation temperature on the structure and supercapacitive performance of GSs has been investigated. Th...Graphene nanosheets(GSs) were prepared from graphite oxide by thermal exfoliation method. The effect of thermal exfoliation temperature on the structure and supercapacitive performance of GSs has been investigated. The results show that the GSs with pore sizes center around 4.0 nm. With an increase of thermal reduction temperature, the number of stacking layers and the structure disorder degree increase, while the oxygen-containing groups content, BET surface area,and electrical resistivity of GSs decrease. The results indicate that 673 K is the preferable thermal exfoliation temperature to acquire good supercapacitive performance. In this case, the GSs have the best supercapacitive performance(233.1 F g-1) in a 6 mol L-1KOH electrolyte. The prepared GSs at the preferable thermal exfoliation temperature have good rate performance and cycle stability.展开更多
Stanene(Sn)-based materials have been extensively applied in industrial production and daily life,but their potential biomedical application remains largely unexplored,which is due to the absence of the appropriate an...Stanene(Sn)-based materials have been extensively applied in industrial production and daily life,but their potential biomedical application remains largely unexplored,which is due to the absence of the appropriate and effective methods for fabricating Sn-based biomaterials.Herein,we explored a new approach combining cryogenic exfoliation and liquid-phase exfoliation to successfully manufacture two-dimensional(2D)Sn nanosheets(SnNSs).The obtained SnNSs exhibited a typical sheet-like structure with an average size of~100 nm and a thickness of~5.1 nm.After PEGylation,the resulting PEGylated SnNSs(SnNSs@PEG)exhibited good stability,superior biocompatibility,and excellent photothermal performance,which could serve as robust photothermal agents for multi-modal imaging(fluorescence/photoacoustic/photothermal imaging)-guided photothermal elimination of cancer.Furthermore,we also used first-principles density functional theory calculations to investigate the photothermal mechanism of SnNSs,revealing that the free electrons in upper and lower layers of SnNSs contribute to the conversion of the photo to thermal.This work not only introduces a new approach to fabricate 2D SnNSs but also establishes the SnNSs-based nanomedicines for photonic cancer theranostics.This new type of SnNSs with great potential in the field of nanomedicines may spur a wave of developing Sn-based biological materials to benefit biomedical applications.展开更多
基金supported by Matching Fund from Thammasat University Research Fund,Thammasat University,under Contract No.MF2/2567the ETS scholarship awarded by Sirindhorn International Institute of Technology,Thammasat University。
文摘Transition metal dichalcogenides(TMDs)have emerged as promising electrocatalysts for various electrocatalytic processes.Molybdenum disulfide has been widely used,but a single electrocatalyst can hardly be applied to all reactions,making it essential to understand the electrochemistry of selected TMDs.Tungsten diselenide(WSe_(2))is reactive in gas evolution processes,similar to molybdenum,yet has received limited attention.This work explores how different exfoliation powers affect WSe_(2)structural configurations and their impact on catalytic performance in hydrogen evolution,oxygen evolution,and capacitive behaviour.The study investigates the structural properties of WSe_(2)nanosheets in both liquid(dispersion)and solid(electrode)phases.Low exfoliation power(90.4 W)contributes to well-defined WSe_(2),while higher power(814 W)leads to an increased number of selenium vacancies.These modifications influence key properties such as thickness,band gaps(1.518 to 1.578 eV),exfoliation yield(0.27 to 0.12 mg mL^(-1)),and oxide content(44.3%to 53.9%),resulting in distinct electrochemical behaviours in different electrolytes.WSe_(2)nanosheets exfoliated at higher power exhibit reduced activity in the hydrogen evolution reaction(HER)due to the loss of W–Se bonds and the formation of an amorphous structure,but they show enhanced oxygen evolution reaction(OER)performance,particularly in alkaline media.Additionally,a higher concentration of selenium vacancies improves capacitive performance in acidic conditions due to proton contributions but are less favourable in neutral and basic electrolytes.This study highlights the importance of exfoliation power in tuning the structural properties of WSe_(2)for specific electrochemical applications,advancing the understanding of its synthesis and performance.
基金supported by the Natural Science Foundation of Zhejiang Province,China(LD24B060002)National Key Research and Development Program of China(2021YFB3801102)the Fundamental Research Funds for the Central Universities(226-2024-00060).
文摘The preparation of dispersible MFI-type zeolite nanoparticles with open micropores is challenging.Herein,a rapid and effective ultrasound-assisted liquid-phase exfoliation method along with a freezedrying process for redispersion of calcined silicalite-1(S-1)zeolite nanoparticle aggregates using 3-aminopropanol as an exfoliating agent is demonstrated.The exfoliation of S-1 zeolite nanoparticles is characterized by X-ray diffraction,scanning electron microscopy and DLS particle size analysis.The effects of drying methods of as-synthesized zeolite nanoparticle suspension,zeolite contents in frozen nanoparticle suspension,exfoliating agent concentrations,and zeolite doses in ultrasonic suspension on exfoliation efficiency are systematically investigated.It is found that the S-1 zeolite nanoparticle(~70 nm)achieves a yield up to 95%through a 30 min ultrasonic exfoliation in a 3-aminopropanol solution along with a freeze-drying process.The proposed exfoliation mechanism involves two primary stages:vip molecule insertion followed by water expansion,both substantially enhanced by tip sonication.This work offers a comprehensive understanding of the exfoliation process,provides valuable insights into the dispersion of sintered zeolite nanoparticles.
基金Projects(62275275,11904239)supported by the National Natural Science Foundation of ChinaProjects(2021JJ40709,2022JJ20080)supported by the Natural Science Foundation of Hunan Province,China。
文摘Ultrathin 2D niobium oxide dichloride(NbOCl_(2))is an emerging member of the 2D ferroelectric material family with extensive potential to provide multifunctionality in electronic devices and nanophotonics elements.It exhibits negligible interlayer electronic coupling and significant excitonic behavior in the bulk state.Here we substantiate that NbOCl_(2) nanosheets can be exfoliated and effectively size-selected using controlled centrifugation techniques by the liquid phase exfoliation(LPE)method.Spectroscopic measurements displayed that the variations in dispersion were highly dependent on the nanosheet dimensions.The nanosheets seemed to be comparatively defect-free which will be further corroborated by high resolution transmission electron microscopy(HRTEM)and Raman analysis.The size selected nanosheets are unanticipated stable in isopropyl alcohol(IPA),possibly owing to the protective influence of a solvation shell.Additionally,the photothermal conversion response and photothermal stability of nanosized NbOCl_(2) were investigated.Our finding revealed that NbOCl_(2) possesses a robust photothermal agent property,boasting a photothermal conversion efficiency of more than 30%.This underscores its promising potential for various photothermal applications in different fields such as photothermal therapy and thermal energy conversion.
基金supported by the National Natural Science Foundation of China(Grant No.52071191).
文摘Exfoliation corrosion(EFC)has rarely been reported for wrought magnesium alloys.Enhanced EFC of the as-extruded Mg–1Li–1Ca alloy was observed after the removal of outermost fine-grained skins.The microstructure and corrosion products were investigated using optical microscopy,scanning electron microscopy,electron backscattered diffraction,X-ray diffraction,and Fourier transform infrared spectrometry.The corrosion behavior was analyzed using electrochemical polarization,electrochemical impedance spectroscopy,and scanning Kelvin probe techniques.The results indicated that the surface of Mg–1Li–1Ca,with the superficial layer removed,was more susceptible to EFC.A linear correlation between grain boundary density and corrosion resistance was established.Additionally,the influence of factors such as grain size,intermetallic compounds,different alloy surfaces,and corrosion products on EFC were discussed,and the corresponding EFC mechanism was clarified.
基金supported by National Science Foundation of China(No.52201254)Natural Science Foundation of Shandong Province(Nos.ZR2020MB090,ZR2020MB027,and ZR2020QE012)+1 种基金the project of“20 Items of University”of Jinan(No.202228046)the Taishan Scholar Project of Shandong Province(No.tsqn202306226)。
文摘The stacking and aggregation of graphene nanosheets have been obstacles to their application as electrode materials for microelectronic devices.This study deploys a one-step,scalable,facile electrochemical exfoliation technique to fabricate nitrogen(N)and chlorine(Cl)co-doped graphene nanosheets(i.e.,N-Cl-G)via the application of constant voltage on graphite in a mixture of 0.1 mol/L H_(2)SO_(4)and 0.1 mol/L NH_(4)Cl without using dangerous and exhaustive operation.The introduction of Cl(with its large radius)and N,both with high electrical negativity,facilitates the modulation of the electronic structure of graphene and creation of rich structural defects in it.Consequently,in the as-constructed supercapacitors,N-Cl-G exhibits a high specific capacitance of 77 F/g at 0.2 A/g and remarkable cycling stability with 91.7%retention of initial capacitance after 20,000 cycles at 10 A/g.Furthermore,a symmetrical supercapacitor assembled with N-Cl-G as the positive and negative electrodes(denoted as N-Cl-G//N-Cl-G)exhibits an energy density of 3.38 Wh/kg at a power density of 600 W/kg and superior cycling stability with almost no capacitance loss after 5000 cycles at 5 A/g.This study provides a scalable protocol for the facile fabrication of high-performance co-doped graphene as an electrode material candidate for supercapacitors.
基金Project(202302AB080024)supported by the Major Science and Technology Projects of the Science and Technology Department of Yunnan Province,ChinaProject(U21A20130)supported by the National Natural Science Foundation of China。
文摘The impact of cooling rate after solution heat treatment on exfoliation corrosion resistance of a Li-containing 7xxx aluminum alloy was investigated by accelerated immersion and electrochemical impedance spectroscopy test,optical microscope,electron backscatter diffraction and scanning transmission electron microscope.With the decrease of cooling rate from 1700℃/s to 4℃/s,exfoliation corrosion resistance of the aged specimens decreases with rating changing from EA to EC and the maximum corrosion depth increasing from about 169.4μm to 632.1μm.Exfoliation corrosion tends to develop along grain boundaries in the specimens with cooling rates higher than about 31℃/s and along both grain boundaries and sub-grain boundaries in the specimens with lower cooling rates.The reason has been discussed based on the changes of the microstructure and microchemistry at grain boundaries and sub-grain boundaries due to slow cooling.
基金the National Natural Science Foundation of China(12074348,12261141661,62204223,52072345,and 12174348)the China Postdoctoral Science Foundation(2022TQ0307)the Natural Science Foundation of Henan Province(242300421179 and 222102310664).
文摘As one promising carbon-based material,sp^(3)-hybrid carbon nitride has been predicted with various novel physicochemical properties.However,the synthesis of sp^(3)-hybrid carbon nitride is still limited by the nanaoscale,low crystallinity,complex source,and expensive instruments.Herein,we have presented a facile approach to the sp^(3)-hybrid carbon nitride nano/micro-crystals with microwave-assisted confining growth and liquid exfoliation.Actually,the carbon nitride nano/micro-crystals can spontaneously emerge and grow in the microwave-assisted polymerization of citric acid and urea,and the liquid exfoliation can break the bulk disorder polymer to retrieve the highly crystalline carbon nitride nano/micro-crystals.The obtained carbon nitride nano/micro-crystals present superior blue light absorption strength and surprising photoluminescence quantum yields of 57.96% in ethanol and 18.05%in solid state.The experimental characterizations and density functional theory calculations reveal that the interface-trapped localized exciton may contribute to the excellent intrinsic light emission capability of carbon nitride nano/micro-crystals and the interparticle staggered stacking will prevent the aggregation-caused-quenching partially.Finally,the carbon nitride nano/micro-crystals are demonstrated to be potentially useful as the phosphor medium in light-emitting-diode for interrupting blue light-induced eye damage.This work paves new light on the synthesis strategy of sp^(3)-hybrid carbon nitride materials and thus may push forward the development of multiple carbon nitride research.
基金financially supported by the Youth talent support program of science and technology association of colleges of Shaanxi Province(Grant No.20190609)the Special scientific research plan of education department of Shaanxi province(Grant No.19JK0190 and 19JK0186)+3 种基金the Natural Science Foundation of Shaanxi Province(Grant No.2019JM508)the Open project of Key laboratory of catalytic foundation and application of Shaanxi province(Grant No.SLGPT2019KF01-23)the Opening Foundation of Shaanxi Key Laboratory of Industrial Automation(No.SLGPT2019KF01-10)the School-level project of Shaanxi University of Technology(Grant No.SLGRC03,SLGRC02)。
文摘With the discovery of graphene,black phosphorus(BP)has been rediscovered as a two-dimensional(2 D)layered material.Since its first preparation in 2014,2 D BP has elicited immense interest,and has exhibited excellent properties,such as distinct pleated structures in layers,adjustable direct bandgap,high carrier mobility,moderate on/off ratio,large specific surface area,and various interesting in-layer anisotropies.However,the realization of these excellent properties depends on the preparation of highquality 2 D BP sheets.Electrochemical exfoliation methods are typically performed under mild conditions,thus,these methods are convenient,controllable,and can produce high-quality 2 D BP sheets.This review summarizes research progress in BP sheets preparation through anodic,cathodic,and electrolyte exfoliation in recent years.Different exfoliating methods affect the quality of 2 D BP sheets.Moreover,possible exfoliating mechanisms and the potential applications of different exfoliating methods are summarized and discussed in detail.Lastly,the shortcomings of existing research on electrochemical exfoliation are presented,and suggestions and prospects for future research on the electrochemical exfoliation of 2 D BP are proposed.
基金Project(2012CB619502)supported by the National Basic Research Program of China
文摘The exfoliation corrosion （EFC） behavior of 7050-T6 aluminum alloy treated with various quench transfer time after solution heat treatment was investigated by standard EFC immersion tests, strength loss measurements after EFC tests and electrochemical impedance spectroscope （EIS） technique. The results showed that EFC resistance of the alloy decreased with increasing quench transfer time. Backscattered electron scanning electron microscope （SEM） together with transmission electron microscope （TEM） observations revealed that the coverage ratio and microstructure of precipitates at grain boundary area are the most important factors which influence the EFC susceptibility of the alloy, while precipitate-free zone （PFZ） near grain boundary has no or only a minor effect on it. In addition, galvanostatic measurements of the alloy present a good correlation between EFC resistance and transients in potential. The cumulated number of transients in potential can be used to evaluate EFC resistance of the alloy.
基金Projects (2010CB731701,2012CB619502) supported by the National Basic Research Program of ChinaProject (50721003) supported by the Creative Research Group of National Natural Science Foundation of China
文摘Influence of dual retrogression and re-aging（dual-RRA） temper on microstructure,strength and exfoliation corrosion（EC） behavior of Al-Zn-Mg-Cu alloy was investigated by hardness measurements,tensile properties tests,exfoliation corrosion tests,transmission electron microscopy（TEM） and scanning electron microscopy（SEM） observation combined energy dispersive X-ray detector（EDX） analysis.Dual-RRA temper maintains the matrix precipitates（MPs） similar to RRA temper,meanwhile obtains coarser and sparser grain boundary precipitates（GBPs） as well as higher Cu and lower Zn content compared with T76 temper.Therefore,dual-RRA temper not only keeps strength equivalent to the RRA temper but also obtains higher EC resistance than T76 temper.
基金supported by the National Natural Science Foundation of China (No. 51571134)the SDUST Research Fund (No. 2014TDJH104)
文摘Exfoliation on as-extruded Mg-1 Li-1 Ca magnesium alloy was investigated after an immersion in 3.5 wt%NaCl aqueous solution for 90, 120 and 150 days through optical microscope, digital camera, scanning electron microscope, electrochemical workstation, scanning Kalvin probe, X-ray diffraction and Fourier transform infrared spectroscope. The results demonstrated that exfoliation corrosion occurred on extruded Mg-1 Li-1 Ca alloy due to elongated microstructure parallel to surface, and delamination of lamellar structure resulted from galvanic effect and wedge effect. Skin layer with fine grains exhibited better corrosion resistance, whereas the interior with coarse grains and the intermetallic compound,Mg2 Ca particles existing in a fibrous structure, dispersed along grain boundaries and extrusion direction in a line. Furthermore, galvanic effect between Mg2 Ca particles and their neighboring a-Mg matrix facilitated dissolution of Mg2 Ca particles and a-Mg matrix; wedge effect was caused by formation of corrosion products. Exfoliation corrosion of extruded Mg-Li-Ca alloys might be a synergic effect of pitting corrosion,filiform corrosion, intergranular corrosion and stress corrosion. Finally, exfoliation corrosion mechanism was proposed.
基金financially supported by the National Natural Science Foundation of China (Nos. 51472253 and 51772306)
文摘Multilayer graphene was prepared by mechanical exfoliation of natural graphite with dioctyl phthalate （DOP） as milling medium without solvent. The obtained mixture could be directly mixed with poly（vinyl chloride） （PVC） for melt-forming, with DOP acting as plasticizer and graphene acting as conductive filler for antistatic performance. The composite showed surface resistance of 2.5 ×10 6 Ω/ at 1 wt% carbon additive, significantly lower than approx. 7 wt% of raw graphite required for achieving the same level. This value is low enough for practical antistatic criterion of 3 × 10 8 Ω/ . The effect of filler addition on mechanical performance was minimal, or even beneficial for the milled carbon in contrast to the case of raw graphite.
基金supported by the National Natural Science Foundation of China(22008221)Startup Research Fund of Zhengzhou University(32211716)+3 种基金Key Scientific Research Projects of Colleges and Universities in Henan Province(21A530005)Guangdong Basic and Applied Basic Research Foundation(2021A1515110789)Hunan Provincial Natural Science Foundation of China(2022JJ40431)Zhengzhou Collaborative Innovation Major Project。
文摘Spent cathode carbon(SCC)from aluminum electrolysis is a potential graphite resource.However,full use of the SCC remains a challenge,since it contains many hazardous substances(e.g.,fluoride salts,cyanides),encapsulated within the thick carbon layers and thus posing serious environmental concerns.This work presents a chemical oxidative exfoliation route to achieve the recycling of SCC and the decontaminated SCC with high-valued graphene oxide(GO)-like carbon structures(SCC-GO)is applied as an excellent adsorbent for organic pollutants.Specifically,after the oxidative exfoliation,the embedded hazardous constituents are fully exposed,facilitating their subsequent removal by aqueous leaching.Moreover,benefiting from the enhanced specific surface areas along with abundant O-containing functional groups,the as-produced SCC-GO,shows an adsorption capacity as high as 347 mg·g^(-1)when considering methylene blue as a pollutant model,which exceeds most of the recently reported carbon-based adsorbents.Our study provides a feasible solution for the efficient recycling of hazardous carbonaceous wastes.
基金support from the National Natural Science Foundation of China(51973054)Young Talents Program in Hunan Province(2020RC3024)+2 种基金Natural Science Funds of Hunan Province for Distinguished Young Scholar(2021JJ10018)Science Research Project of Hunan Provincial Education Department(21B0027)High-level Innovative Talent Project in Hunan Province(2018RS3055).
文摘Flexible yet highly thermoconductive materials are essential for the development of next-generation flexible electronic devices.Herein,we report a bioinspired nanostructured film with the integration of large ductility and high thermal conductivity based on self-exfoliated pristine graphene and three-dimensional aramid nanofiber network.A self-grinding strategy to directly exfoliate flake graphite into few-layer and few-defect pristine graphene is successfully developed through mutual shear friction between graphite particles,generating largely enhanced yield and productivity in comparison to normal liquid-based exfoliation strategies,such as ultrasonication,high-shear mixing and ball milling.Inspired by nacre,a new bioinspired layered structural design model containing three-dimensional nanofiber network is proposed and implemented with an interconnected aramid nanofiber network and high-loading graphene nanosheets by a developed continuous assembly strategy of sol-gel-film transformation.It is revealed that the bioinspired film not only exhibits nacre-like ductile deformation behavior by releasing the hidden length of curved aramid nanofibers,but also possesses good thermal transport ability by directionally conducting heat along pristine graphene nanosheets.
基金Project(2012CB619500) supported by the National Basic Research Program of ChinaProject(201012200238) supported from the Freedom Explore Program of Central South University, China
文摘The influence of exfoliation corrosion on the tensile properties of a high strength Al-Zn-Mg-Cu alloy was investigated by ambient temperature tensile testing, optical microscopy, transmission electron microscopy （TEM）, scanning electron microscopy （SEM） and electron backscatter diffraction （EBSD）. After exfoliation corrosion immersion, blisters and corrosion pits can be seen on the sheet surface, which lead to loss of materials and notches. A number of intergranular cracks are observed to initiate at the bottom of the corrosion-induced notches and propagate rapidly into the bulk materials during tensile. Consequently, exfoliation corrosion results in significant loss of strength and brittle fracture. EBSD results show that the crack propagation path is primarily along the grain boundaries with misorientation of-45°, and coincidence site lattice （CSL） boundaries are slightly more resistant to crack.
基金National Natural Science Foundation of China,Grant/Award Numbers:51678163,91851202Australian Research Council,Grant/Award Number:FT160100107 and DP180102210。
文摘Synthesis of structurally controlled graphene materials is critical for realizing their practical applications.The electrochemical exfoliation of graphite has emerged as a simple method to produce graphene materials.This review examines research progress in the last 5 years,from 2015 to 2019.Graphene material synthesis methods generally have a trade‐off between increasing production yield and achieving better material property control.The synthesis conditions for synthesizing pristine graphene,graphene oxide(GO),and graphene composites are significantly different.Thus,in this review,we first discuss synthesis methods for graphene materials with high C/O ratios from four aspects:graphite electrodes,equipment engineering,electrolytes,and additional reduction methods.Next,we survey synthesis methods for GO and examine how the pretreatment of the graphite electrodes,electrolytes,and operation parameters,such as applied voltages,electrolyte temperatures,and mechanical forces,affect the quality of GO.Further,we summarize electrochemical exfoliation methods used to dope graphene materials,introduce covalent functional groups,incorporate various nanoparticles,and assembly of graphene architectures.For all synthesis methods,we compare the properties of resulting graphene materials such as C/O ratios,lateral size,layer numbers,and quality characterized by Raman spectroscopy.Lastly,we propose our perspectives on further research.We hope this review stimulates more studies to realize the on‐demand production of graphene materials with desired properties using electrochemical exfoliation methods.
基金Jiangsu Province Six Talent Peaks Project(No.2014-XCL-013)Jiangsu Industrial-academicresearch Prospective Joint Project(No.BY2016069-02)+1 种基金the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education InstitutionsTop-notch Academic Programs Project of Jiangsu Higher Education Institutions(No.PPZY2015B112)。
文摘The low cost and facile scalable exfoliation route for two-dimensional hexagonal boron nitride(h-BN)was still indispensable for potential applications.In this work,we presented a convenient and scalable exfoliation for few-layer BNNSs.Taking advantage of the advantages of swift heating of microwave and ultra low temperature vaporization of liquid nitrogen,bulk h-BN was high-efficiently exfoliated into fewlayer BNNSs.The as-exfoliated BNNSs had a 2-6 nm thickness and approximately 7.91%yield,exhibiting scalable,facile and environment-friendly features.Furthermo re,the as-exfoliated BNNSs we re applied as additive in oil for reducing friction of oil.The COF of the BNNSs-based grease reduced by 20.10% compared to grease,and the antiwear performance decreased by 55.8% and 45.1% relative to grease and h-BN-based grease.
基金supported by the National Natural Science Foundation of China (Grant No. 41272051)the Doctor Foundation of Southwest University of Science and Technology (Grant No. 11ZX7135)
文摘Graphene nanosheets(GSs) were prepared from graphite oxide by thermal exfoliation method. The effect of thermal exfoliation temperature on the structure and supercapacitive performance of GSs has been investigated. The results show that the GSs with pore sizes center around 4.0 nm. With an increase of thermal reduction temperature, the number of stacking layers and the structure disorder degree increase, while the oxygen-containing groups content, BET surface area,and electrical resistivity of GSs decrease. The results indicate that 673 K is the preferable thermal exfoliation temperature to acquire good supercapacitive performance. In this case, the GSs have the best supercapacitive performance(233.1 F g-1) in a 6 mol L-1KOH electrolyte. The prepared GSs at the preferable thermal exfoliation temperature have good rate performance and cycle stability.
基金the US METAvivor Early Career Investigator Award(W.T.)and Harvard Medical School/Brigham and Women’s Hospital Department of Anesthesiology-Basic Scientist Grant(W.T.)National Natural Science Foundation of China(Nos.21877049,21807117)+2 种基金Major Program for Tackling Key Problems of Industrial Technology in Guangzhou(201902020013)Dedicated Fund for Promoting High-Quality Marine Economic Development in Guangdong Province(GDOE-2019-A31,2020-035)Dr J.Ouyang was supported by the China Postdoctoral Science Foundation(No.2020M683173).
文摘Stanene(Sn)-based materials have been extensively applied in industrial production and daily life,but their potential biomedical application remains largely unexplored,which is due to the absence of the appropriate and effective methods for fabricating Sn-based biomaterials.Herein,we explored a new approach combining cryogenic exfoliation and liquid-phase exfoliation to successfully manufacture two-dimensional(2D)Sn nanosheets(SnNSs).The obtained SnNSs exhibited a typical sheet-like structure with an average size of~100 nm and a thickness of~5.1 nm.After PEGylation,the resulting PEGylated SnNSs(SnNSs@PEG)exhibited good stability,superior biocompatibility,and excellent photothermal performance,which could serve as robust photothermal agents for multi-modal imaging(fluorescence/photoacoustic/photothermal imaging)-guided photothermal elimination of cancer.Furthermore,we also used first-principles density functional theory calculations to investigate the photothermal mechanism of SnNSs,revealing that the free electrons in upper and lower layers of SnNSs contribute to the conversion of the photo to thermal.This work not only introduces a new approach to fabricate 2D SnNSs but also establishes the SnNSs-based nanomedicines for photonic cancer theranostics.This new type of SnNSs with great potential in the field of nanomedicines may spur a wave of developing Sn-based biological materials to benefit biomedical applications.
