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
As an alternative to lithium-ion batteries,aqueous zinc-graphite batteries(ZnGBs)are being explored as safer and low-cost options with the expectation of scalability to large energy storage systems.However,the current...As an alternative to lithium-ion batteries,aqueous zinc-graphite batteries(ZnGBs)are being explored as safer and low-cost options with the expectation of scalability to large energy storage systems.However,the currently adopted polyatomic and metal complex anion intercalation process at the graphite electrode in ZnGB exhibits poor electrochemical performances.Alternatively,incorporating halogen anions offers exceptional electrochemical performance to graphite electrodes due to their redox process.In this work,ZnGBs are assembled using a LiCl/ZnCl2/KBr^(-)based water-in-salt electrolyte,which efficiently supplies bromide(Br^(−))ions for conversion into Br_(x)^(−)and facilitates Br_(2)intercalation at the graphite electrode.The conversion and intercalation of bromine together enable the ZnGB to achieve a discharge capacity of 2.73 mAh/cm^(2)with 91.0%of coulombic efficiency(CE)while supporting high current density operations of up to 150 mA/cm^(2).With high energy density(4.56 Wh/cm^(2)),high power density(199.5 mW/cm^(2)),and excellent rate capability(∼93.0%CE at 150 mA/cm^(2)),the ZnGB is shown to operate efficiently for as much as 800 cycles.Beguilingly,an anode-free ZnGB offers enhanced stability for up to 1100 cycles without performance decay,matching the electrochemical performance of Zn metal electrodes.This work provides insights into the bromine reaction mechanism at graphite electrodes and the role of surface exfoliation in enabling efficient Br_(x)^(−)formation,along with Br_(2)intercalation,for achieving high-performance ZnGBs.展开更多
The corrosion resistance and mechanical properties of peak-aged AlZnMgCu alloys containing Si and Er elements were investigated with hardness test,tensile test,intergranular corrosion test,exfoliation corrosion test a...The corrosion resistance and mechanical properties of peak-aged AlZnMgCu alloys containing Si and Er elements were investigated with hardness test,tensile test,intergranular corrosion test,exfoliation corrosion test and transmission electron microscopy.The results indicate that peak-aged AlZnMgCuSiEr alloy is strengthened by co-precipitation of η′phases and nano-sized GPB-Ⅱ zones.The yield strength of the AlZnMgCu alloy is increased by 38.5 MPa and the elongation is increased by 4.5%.At the same time,the corrosion resistance of the AlZnMgCuSiEr alloy is enhanced due to the synergistic effect of Er and Si.The maximum intergranular corrosion(IGC)depth decreases from 264.2 to 9.9μm.The fundamental reason is that the co-addition of Si and Er regulates the evolution of precipitated phases in grains and at grain boundaries.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
To effectively improve the corrosion resistance of aluminum alloys without affecting their strength, the effect of Ce content on the microstructure, stress corrosion, intergranular corrosion, and exfoliation corrosion...To effectively improve the corrosion resistance of aluminum alloys without affecting their strength, the effect of Ce content on the microstructure, stress corrosion, intergranular corrosion, and exfoliation corrosion resistances of Al−11.3Zn−3.1Mg−1.2Cu−0.2Zr−0.1Ti alloy was investigated. The results showed that the addition of Ce formed the (Zn,Al,Cu)_(22)Ce_(3) phase with a size of 100 nm, which enhanced the recrystallization resistance of the alloy, increased the number of low-angle grain boundaries and dislocation density, refined the grains, promoted the phase transition from GP zone to η' phase, and promoted the size and discontinuity of precipitates at grain boundaries. All Ce-added alloys exhibited the higher resistance to corrosion. The alloy with 0.15 wt.% Ce possessed the optimal corrosion resistance along with the strength and elongation at slow strain rate of 744.8 MPa and 4.6%, respectively, in 3.5 wt.% NaCl solution. The minimum depth of intergranular corrosion and exfoliation corrosion was achieved as well.展开更多
Rechargeable aqueous aluminum ion batteries(AIBs)are inspiring researchers’enthusiasm due to the low cost and high theoretical capacity of aluminum.Polyaniline(PANI)materials have the potential for aluminum ion stora...Rechargeable aqueous aluminum ion batteries(AIBs)are inspiring researchers’enthusiasm due to the low cost and high theoretical capacity of aluminum.Polyaniline(PANI)materials have the potential for aluminum ion storage due to the properties of its excellent conductivity and inherent theoretical capacity.However,the poor cycling stability and low loadings of PANI limit its application in energy storage.In this study,PANI-x electrodes with high mass loadings are successfully prepared by the electrodeposition method for reversible AlCl_(2)^(+)storage.Among them,the PANI-2 electrode possesses the highest areal capacity(0.59 and 0.51 mAh cm^(−2)at the current density of 0.5 and 10 mA cm^(−2))and excellent cycling stability in saturated AlCl3.Ex situ N 1s fitting spectra of PANI-2 and molecular dynamics simulations of 1 M,3 M,and saturated AlCl_(3)electrolytes demonstrate that PANI can achieve reversible redox reactions in saturated AlCl3,thereby achieving its excellent stability.Density functional theory calculations and ex situ spectra characterizations of PANI-2 demonstrate the insertion/de-insertion mechanism in the form of AlCl_(2)^(+)ions.In conclusion,PANI-2|Saturated AlCl_(3)|EG(exfoliated graphite foil)full cell is assembled successfully.This work provides promising guidance for the preparation of high-loading electrodes for AIBs.展开更多
The effects of interrupted aging on mechanical properties and corrosion resistance of 7A75 aluminum alloy extruded bar were investigated through various analyses,including electrical conductivity,mechanical properties...The effects of interrupted aging on mechanical properties and corrosion resistance of 7A75 aluminum alloy extruded bar were investigated through various analyses,including electrical conductivity,mechanical properties,local corrosion properties,and slow strain rate tensile stress corrosion tests.Microstructure characterization techniques such as metallographic microscopy,scanning electron microscopy(SEM),and transmission electron microscopy(TEM)were also employed.The results indicate that the tensile strength of the alloy produced by T6I6 aging is similar to that produced by T6I4 aging,and it even exceeds 700 MPa.Furthermore,the yield strength increases by 52.7 MPa,reaching 654.8 MPa after T6I6 aging treatment.The maximum depths of intergranular corrosion(IGC)and exfoliation corrosion(EXCO)decrease from 116.3 and 468.5μm to 89.5 and 324.3μm,respectively.The stress corrosion factor also decreases from 2.1%to 1.6%.These findings suggest that the alloy treated with T6I6 aging exhibits both high strength and excellent stress corrosion cracking resistance.Similarly,when the alloy is treated with T6I4,T6I6 and T6I7 aging,the sizes of grain boundary precipitates(GBPs)are found to be 5.2,18.4,and 32.8 nm,respectively.The sizes of matrix precipitates are 4.8,5.7 and 15.7 nm,respectively.The atomic fractions of Zn in GBPs are 9.92 at.%,8.23 at.%and 6.87 at.%,respectively,while the atomic fractions of Mg are 12.66 at.%,8.43 at.%and 7.00 at.%,respectively.Additionally,the atomic fractions of Cu are 1.83 at.%,2.47 at.%and 3.41 at.%,respectively.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
Fluorographene(FG)with narrow lateral size and thickness distributions was prepared by a liquid-phase exfoliation method,based on liquid cascade centrifugation.The Rtec MFT-5000 tribo-meter was used to investigate the...Fluorographene(FG)with narrow lateral size and thickness distributions was prepared by a liquid-phase exfoliation method,based on liquid cascade centrifugation.The Rtec MFT-5000 tribo-meter was used to investigate the lubricating performance of bentonite grease enhanced by the as-prepared FG.The results showed that the coefficient of friction and the wear volume of bentonite grease with 0.3 wt%FG were decreased by 20.4%and 44.9%,respectively,as compared to those of the base grease.The main reason is that FG can promote the formation of the tribo-chemical reaction film consisting of complex carbon oxide,Fe_(2)O_(3)and FeF_(3)on the friction surface,which can remarkably improve the performance of friction reduction and prevent the appearance of severe wear.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
Liquid-phase exfoliation was employed to synthesize Sr_(2)Nb_(3)O_(10) perovskite nanosheets with thicknesses down to 1.76 nm.Transmission electron microscopy(TEM),atomic force microscope(AFM),X-ray photoelectron spec...Liquid-phase exfoliation was employed to synthesize Sr_(2)Nb_(3)O_(10) perovskite nanosheets with thicknesses down to 1.76 nm.Transmission electron microscopy(TEM),atomic force microscope(AFM),X-ray photoelectron spectrometer(XPS),and other characterization techniques were used to evaluate the atomic structure and chemical composition of the exfoliated nanosheets.A UV photodetector based on individual Sr_(2)Nb_(3)O_(10) nanosheets was prepared to demonstrate the application of an ultraviolet(UV) photodetector.The UV photodetector exhibited outstanding photocurrent and responsivity with a responsivity of 3×10^(5) A·W^(-1) at 5 V bias under 280 nm illumination,a photocurrent of 60 nA,and an on/off ratio of 3×10^(2).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
Measuring the tanning skin can provide a scientific method to evaluate the efficacy of cosmetics exfoliator.Dihydroxyacetone(DHA,5.0%(w/w))was used to stain the inner forearms cuticle of subjects.The skin surface L*an...Measuring the tanning skin can provide a scientific method to evaluate the efficacy of cosmetics exfoliator.Dihydroxyacetone(DHA,5.0%(w/w))was used to stain the inner forearms cuticle of subjects.The skin surface L*and b*were determined,then ITA and its recovery rate were calculated to evaluate the exfoliating efficacy of cosmetics.The results showed that no significant(P≥0.05)differences were observed for L*,b*and ITA on different skin surface of unstained subjects.After staining with DHA,no adverse reaction was found in the stained areas,and the changes of L*,b*and ITA on different skin surface were consistent(P≥0.05).Two different cosmetics were used continuously to exfoliate the skin in different areas.After treatment for 7 days,the corresponding areas of skin L*,b*and ITA had significant(P<0.05)improvement in comparison with negative control area.But there were differences in the evaluation results of the exfoliation efficacy using these three parameters.The recovery rate of ITA of two samples improved significantly(P<0.05)than the negative control area.The work indicated that using 5.0%DHA for skin browning and measuring the skin surface color change by ITA recovery rate can accurately and sensitively assess the skin cuticle renewal rate difference.This method can be used as one of the effective way to evaluate the efficacy of cosmetics exfoliation.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
The corrosion resistance of Al？Zn？Mg alloy subjected to different times in flame rectification was investigated based on the exfoliation corrosion test. The results indicate that the flame rectification deteriorate...The corrosion resistance of Al？Zn？Mg alloy subjected to different times in flame rectification was investigated based on the exfoliation corrosion test. The results indicate that the flame rectification deteriorates the exfoliation corrosion resistance of Al？Zn？Mg alloy. The corrosion resistance of Al-Zn-Mg alloy is ranked in the following order： base metal〉two times〉three times〉one time of flame rectification. The exfoliation corrosion behavior was discussed based on the transformation of precipitates at grain boundaries and matrix. With increasing the number of times in flame rectification, the precipitate-free zones disappeared and the precipitates experienced dissolution and re-precipitation. The sample was seriously corroded after one time of flame rectification, because the precipitates at grain boundaries are more continuous than those in other samples.展开更多
Mesenchymal stem cells(MSCs) as a source for regenerative medicine are now the subject of much clinical attention. There are high expectations due to their safety, low tumorigenic risk, and low ethical concerns. MSC t...Mesenchymal stem cells(MSCs) as a source for regenerative medicine are now the subject of much clinical attention. There are high expectations due to their safety, low tumorigenic risk, and low ethical concerns. MSC therapy has been approved for acute graft-versus host diseases since 2015. Tooth-derived MSCs are known to have a great potential in their proliferation and differentiation capacities, even when compared with bone-marrow-derived MSCs. In particular, stem cells from human exfoliated deciduous teeth(SHEDs) are the best candidates for personal cell banking(dental pulp cell bank), because they can be obtained less invasively in the natural process of individual growth. SHEDs are known to differentiate into hepatocytes. There have been several studies showing the effectiveness of SHEDs on the treatment of liver failure in animal models. They may exert their effects either by repopulation of cells in injured liver or by paracrine mechanisms due to their immuneregulatory functions. Moreover, it may be possible to use each individuals' dental pulp cells as a future source of tailor-made differentiated hepatocytes in the context of a bioartificial liver or liver-on-a-chip to screen for drug toxicity.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The authors acknowledge the University of Sharjah for financial support through a competitive research project grant(project number:23020406277)。
文摘As an alternative to lithium-ion batteries,aqueous zinc-graphite batteries(ZnGBs)are being explored as safer and low-cost options with the expectation of scalability to large energy storage systems.However,the currently adopted polyatomic and metal complex anion intercalation process at the graphite electrode in ZnGB exhibits poor electrochemical performances.Alternatively,incorporating halogen anions offers exceptional electrochemical performance to graphite electrodes due to their redox process.In this work,ZnGBs are assembled using a LiCl/ZnCl2/KBr^(-)based water-in-salt electrolyte,which efficiently supplies bromide(Br^(−))ions for conversion into Br_(x)^(−)and facilitates Br_(2)intercalation at the graphite electrode.The conversion and intercalation of bromine together enable the ZnGB to achieve a discharge capacity of 2.73 mAh/cm^(2)with 91.0%of coulombic efficiency(CE)while supporting high current density operations of up to 150 mA/cm^(2).With high energy density(4.56 Wh/cm^(2)),high power density(199.5 mW/cm^(2)),and excellent rate capability(∼93.0%CE at 150 mA/cm^(2)),the ZnGB is shown to operate efficiently for as much as 800 cycles.Beguilingly,an anode-free ZnGB offers enhanced stability for up to 1100 cycles without performance decay,matching the electrochemical performance of Zn metal electrodes.This work provides insights into the bromine reaction mechanism at graphite electrodes and the role of surface exfoliation in enabling efficient Br_(x)^(−)formation,along with Br_(2)intercalation,for achieving high-performance ZnGBs.
基金funded by the National Key Research and Development Program of China(Nos.2021YFB3700902,2021YFB3704204,and 2021YFB3704205)the Beijing Lab Project for Modern Transportation Metallic Materials and Processing Technology,China,the Jiangsu Key Laboratory for Clad Materials,China(No.BM2014006)+4 种基金the Doctor Funds of Taiyuan University of Science and Technology,China(No.20222063)the Fundamental Research Program of Shanxi Province,China(No.202303021212216)the Award Fund for Outstanding Doctors in Shanxi Province,China(No.20232045)the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi Province,China(Nos.2022L289,and 2022L280)the Special Project for Transformation of Scientific Achievements,China(No.202204021301025)。
文摘The corrosion resistance and mechanical properties of peak-aged AlZnMgCu alloys containing Si and Er elements were investigated with hardness test,tensile test,intergranular corrosion test,exfoliation corrosion test and transmission electron microscopy.The results indicate that peak-aged AlZnMgCuSiEr alloy is strengthened by co-precipitation of η′phases and nano-sized GPB-Ⅱ zones.The yield strength of the AlZnMgCu alloy is increased by 38.5 MPa and the elongation is increased by 4.5%.At the same time,the corrosion resistance of the AlZnMgCuSiEr alloy is enhanced due to the synergistic effect of Er and Si.The maximum intergranular corrosion(IGC)depth decreases from 264.2 to 9.9μm.The fundamental reason is that the co-addition of Si and Er regulates the evolution of precipitated phases in grains and at grain boundaries.
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financially supported from the Key Project of Equipment Pre-research Foundation of the Ministry of Equipment Development of the Central Military Commission of China(No.6140922010201)the Key Project of Research and Development of Zhenjiang Province,China(No.GY2018021)。
文摘To effectively improve the corrosion resistance of aluminum alloys without affecting their strength, the effect of Ce content on the microstructure, stress corrosion, intergranular corrosion, and exfoliation corrosion resistances of Al−11.3Zn−3.1Mg−1.2Cu−0.2Zr−0.1Ti alloy was investigated. The results showed that the addition of Ce formed the (Zn,Al,Cu)_(22)Ce_(3) phase with a size of 100 nm, which enhanced the recrystallization resistance of the alloy, increased the number of low-angle grain boundaries and dislocation density, refined the grains, promoted the phase transition from GP zone to η' phase, and promoted the size and discontinuity of precipitates at grain boundaries. All Ce-added alloys exhibited the higher resistance to corrosion. The alloy with 0.15 wt.% Ce possessed the optimal corrosion resistance along with the strength and elongation at slow strain rate of 744.8 MPa and 4.6%, respectively, in 3.5 wt.% NaCl solution. The minimum depth of intergranular corrosion and exfoliation corrosion was achieved as well.
基金supported by the National Natural Science Foundation of China(Grant No.21906015)the Fundamental Research Funds for the Central Universities(Grant No.N2205006 and N2225013).
文摘Rechargeable aqueous aluminum ion batteries(AIBs)are inspiring researchers’enthusiasm due to the low cost and high theoretical capacity of aluminum.Polyaniline(PANI)materials have the potential for aluminum ion storage due to the properties of its excellent conductivity and inherent theoretical capacity.However,the poor cycling stability and low loadings of PANI limit its application in energy storage.In this study,PANI-x electrodes with high mass loadings are successfully prepared by the electrodeposition method for reversible AlCl_(2)^(+)storage.Among them,the PANI-2 electrode possesses the highest areal capacity(0.59 and 0.51 mAh cm^(−2)at the current density of 0.5 and 10 mA cm^(−2))and excellent cycling stability in saturated AlCl3.Ex situ N 1s fitting spectra of PANI-2 and molecular dynamics simulations of 1 M,3 M,and saturated AlCl_(3)electrolytes demonstrate that PANI can achieve reversible redox reactions in saturated AlCl3,thereby achieving its excellent stability.Density functional theory calculations and ex situ spectra characterizations of PANI-2 demonstrate the insertion/de-insertion mechanism in the form of AlCl_(2)^(+)ions.In conclusion,PANI-2|Saturated AlCl_(3)|EG(exfoliated graphite foil)full cell is assembled successfully.This work provides promising guidance for the preparation of high-loading electrodes for AIBs.
基金the Tianjin Key Laboratory of Fastening and Connection Technology Enterprises 2022—2023,China(No.TKLF2022-02-C-02)the technical support from the School of Materials Science and Engineering,Central South University,China.
文摘The effects of interrupted aging on mechanical properties and corrosion resistance of 7A75 aluminum alloy extruded bar were investigated through various analyses,including electrical conductivity,mechanical properties,local corrosion properties,and slow strain rate tensile stress corrosion tests.Microstructure characterization techniques such as metallographic microscopy,scanning electron microscopy(SEM),and transmission electron microscopy(TEM)were also employed.The results indicate that the tensile strength of the alloy produced by T6I6 aging is similar to that produced by T6I4 aging,and it even exceeds 700 MPa.Furthermore,the yield strength increases by 52.7 MPa,reaching 654.8 MPa after T6I6 aging treatment.The maximum depths of intergranular corrosion(IGC)and exfoliation corrosion(EXCO)decrease from 116.3 and 468.5μm to 89.5 and 324.3μm,respectively.The stress corrosion factor also decreases from 2.1%to 1.6%.These findings suggest that the alloy treated with T6I6 aging exhibits both high strength and excellent stress corrosion cracking resistance.Similarly,when the alloy is treated with T6I4,T6I6 and T6I7 aging,the sizes of grain boundary precipitates(GBPs)are found to be 5.2,18.4,and 32.8 nm,respectively.The sizes of matrix precipitates are 4.8,5.7 and 15.7 nm,respectively.The atomic fractions of Zn in GBPs are 9.92 at.%,8.23 at.%and 6.87 at.%,respectively,while the atomic fractions of Mg are 12.66 at.%,8.43 at.%and 7.00 at.%,respectively.Additionally,the atomic fractions of Cu are 1.83 at.%,2.47 at.%and 3.41 at.%,respectively.
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Funded by Science and Technology Research Program of Chongqing Municipal Education Commission(No.KJZD-K202212905)Natural Science Foundation of Chongqing,China(No.cstc2019jcyj-msxmX0453)。
文摘Fluorographene(FG)with narrow lateral size and thickness distributions was prepared by a liquid-phase exfoliation method,based on liquid cascade centrifugation.The Rtec MFT-5000 tribo-meter was used to investigate the lubricating performance of bentonite grease enhanced by the as-prepared FG.The results showed that the coefficient of friction and the wear volume of bentonite grease with 0.3 wt%FG were decreased by 20.4%and 44.9%,respectively,as compared to those of the base grease.The main reason is that FG can promote the formation of the tribo-chemical reaction film consisting of complex carbon oxide,Fe_(2)O_(3)and FeF_(3)on the friction surface,which can remarkably improve the performance of friction reduction and prevent the appearance of severe wear.
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Funded by the National Natural Science Foundation of China(Nos.51872214 and 52172124)the Fundamental Research Funds for the Central Universities(WUT:2021Ⅲ019JC and 2018Ⅲ041GX)。
文摘Liquid-phase exfoliation was employed to synthesize Sr_(2)Nb_(3)O_(10) perovskite nanosheets with thicknesses down to 1.76 nm.Transmission electron microscopy(TEM),atomic force microscope(AFM),X-ray photoelectron spectrometer(XPS),and other characterization techniques were used to evaluate the atomic structure and chemical composition of the exfoliated nanosheets.A UV photodetector based on individual Sr_(2)Nb_(3)O_(10) nanosheets was prepared to demonstrate the application of an ultraviolet(UV) photodetector.The UV photodetector exhibited outstanding photocurrent and responsivity with a responsivity of 3×10^(5) A·W^(-1) at 5 V bias under 280 nm illumination,a photocurrent of 60 nA,and an on/off ratio of 3×10^(2).
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.
文摘Measuring the tanning skin can provide a scientific method to evaluate the efficacy of cosmetics exfoliator.Dihydroxyacetone(DHA,5.0%(w/w))was used to stain the inner forearms cuticle of subjects.The skin surface L*and b*were determined,then ITA and its recovery rate were calculated to evaluate the exfoliating efficacy of cosmetics.The results showed that no significant(P≥0.05)differences were observed for L*,b*and ITA on different skin surface of unstained subjects.After staining with DHA,no adverse reaction was found in the stained areas,and the changes of L*,b*and ITA on different skin surface were consistent(P≥0.05).Two different cosmetics were used continuously to exfoliate the skin in different areas.After treatment for 7 days,the corresponding areas of skin L*,b*and ITA had significant(P<0.05)improvement in comparison with negative control area.But there were differences in the evaluation results of the exfoliation efficacy using these three parameters.The recovery rate of ITA of two samples improved significantly(P<0.05)than the negative control area.The work indicated that using 5.0%DHA for skin browning and measuring the skin surface color change by ITA recovery rate can accurately and sensitively assess the skin cuticle renewal rate difference.This method can be used as one of the effective way to evaluate the efficacy of cosmetics exfoliation.
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Projects(51374048,50904012)supported by the National Natural Science Foundation of China
文摘The corrosion resistance of Al？Zn？Mg alloy subjected to different times in flame rectification was investigated based on the exfoliation corrosion test. The results indicate that the flame rectification deteriorates the exfoliation corrosion resistance of Al？Zn？Mg alloy. The corrosion resistance of Al-Zn-Mg alloy is ranked in the following order： base metal〉two times〉three times〉one time of flame rectification. The exfoliation corrosion behavior was discussed based on the transformation of precipitates at grain boundaries and matrix. With increasing the number of times in flame rectification, the precipitate-free zones disappeared and the precipitates experienced dissolution and re-precipitation. The sample was seriously corroded after one time of flame rectification, because the precipitates at grain boundaries are more continuous than those in other samples.
基金Supported by Grant-in-Aid for Scientific Research from the Japan Society for the Promotion of Science,No.17K08966(to Ohkoshi S)
文摘Mesenchymal stem cells(MSCs) as a source for regenerative medicine are now the subject of much clinical attention. There are high expectations due to their safety, low tumorigenic risk, and low ethical concerns. MSC therapy has been approved for acute graft-versus host diseases since 2015. Tooth-derived MSCs are known to have a great potential in their proliferation and differentiation capacities, even when compared with bone-marrow-derived MSCs. In particular, stem cells from human exfoliated deciduous teeth(SHEDs) are the best candidates for personal cell banking(dental pulp cell bank), because they can be obtained less invasively in the natural process of individual growth. SHEDs are known to differentiate into hepatocytes. There have been several studies showing the effectiveness of SHEDs on the treatment of liver failure in animal models. They may exert their effects either by repopulation of cells in injured liver or by paracrine mechanisms due to their immuneregulatory functions. Moreover, it may be possible to use each individuals' dental pulp cells as a future source of tailor-made differentiated hepatocytes in the context of a bioartificial liver or liver-on-a-chip to screen for drug toxicity.
