Despite the safety,low cost,and high theoretical capacity(820 mA h g^(-1))of Zn metal anodes,the practical application of aqueous Zn metal batteries remains a critical challenge due to the Zn dendrite growth,corrosion...Despite the safety,low cost,and high theoretical capacity(820 mA h g^(-1))of Zn metal anodes,the practical application of aqueous Zn metal batteries remains a critical challenge due to the Zn dendrite growth,corrosion,and hydrogen evolution reaction.Herein,we demonstrate the MXene ink hosting Zn metal anodes(MX@Zn)for high-performance and patternable Zn metal full batteries.The as-designed MX@Zn electrode is more facile and reversible than bare Zn and CC@Zn,as verified by better cyclic stability and lower overpotentials of symmetric cells with the plating capacity of 0.05 mA h cm^(-2)at 0.1 m A cm^(-2)and of 1 m A h cm^(-2)at 1 m A cm^(-2).The MX@Zn|MnO_(2)full cells deliver a high specific capacity of 281.9 m A h g^(-1),91.5%of the theoretical capacity,achieving 50%capacity retention from 60 mA g^(-1)to 300 mA g^(-1)and 79.7%of initial capacity after 200 cycles.Moreover,the patterned devices based on the MX@Zn electrode achieve high energy and power densities of 348.57 Wh kg^(-1)and 1556 W kg^(-1),respectively,along with a capacity retention of 64%and Coulombic efficiency of 99%over 500 cycles.The high performance of MX@Zn is attributed to the high electrical conductivity and hydrophilicity of MXene and rapid ion diffusion through the 3D interconnected porous channels.展开更多
While transition-metal oxides such as α-MoO_(3)provide high capacity,their use is limited by modest electronic conductivity and electrochemical instability in aqueous electrolytes.Two-dimensional(2D)MXenes,offer meta...While transition-metal oxides such as α-MoO_(3)provide high capacity,their use is limited by modest electronic conductivity and electrochemical instability in aqueous electrolytes.Two-dimensional(2D)MXenes,offer metallic conductivity,but their capacitance is limited in aqueous electrolytes.Insertion of partially solvated cations into Ti_(3)C_(2)MXene from lithium-based water-in-salt(WIS)electrolytes enables charge storage at positive potentials,allowing a wider potential window and higher capacitance.Herein,we demonstrate that α-MoO_(3)/Ti_(3)C_(2)hybrids combine the high capacity of α-MoO_(3)and conductivity of Ti_(3)C_(2)in WIS(19.8 m LiCI)electrolyte in a wide1.8 V voltage window.Cyclic voltammograms reveal multiple redox peaks from α-MoO_(3)in addition to the well-separated peaks of Ti_(3)C_(2)in the hybrid electrode.This leads to a higher specific charge and a higher rate capability compared to a carbon and binder containing α-MoO_(3)electrode.These results demonstrate that the addition of MXene to less conductive oxides eliminates the need for conductive carbon additives and binders,leads to a larger amount of charge stored,and increases redox capacity at higher rates.In addition,MXene encapsulated α-MoO_(3)showed improved electrochemical stability,which was attributed to the suppressed dissolution of α-MoO_(3).The work suggests that oxide/MXene hybrids are promising for energy storage.展开更多
MXene nanosheets have been used for preparing highly flexible integrated electrodes due to their two-dimensional(2D)morphology,flexibility,high conductivity,and abundant functional groups.However,restacking of 2D nano...MXene nanosheets have been used for preparing highly flexible integrated electrodes due to their two-dimensional(2D)morphology,flexibility,high conductivity,and abundant functional groups.However,restacking of 2D nanosheets inhibits the ion transport in MXene electrodes,limiting their thickness,rate performance,and energy storage capacity.Here,we employed a natural sedimentation method instead of the conventional vacuum-assisted filtration to prepare flexible Ti3C2TxMXene films with enlarged interlayer spacing,which facilitates the access of the lithium ions to the interlayers and thus leads to a greatly enhanced electrochemical performance.The naturally sedimented flexible film shows a double lithium storage capacity compared to the conventional vacuum-filtered MXene film,along with improved rate performance and excellent cycle stability.展开更多
Intercalation redox materials have shown great promise for efficient water desalination due to available faradaic gallery sites.Symmetric capacitive deionization(CDI)cells previously demonstrated using MXenes were oft...Intercalation redox materials have shown great promise for efficient water desalination due to available faradaic gallery sites.Symmetric capacitive deionization(CDI)cells previously demonstrated using MXenes were often limited in their salt adsorption capacity(SAC)and voltage window of operation.In this study,current collector-and binder-free Ti3C2Tx MXene electrode architectures are designed with porous carbon as the positive electrode to demonstrate hybrid CDI(HCDI)operation.Furthermore,MXene current collectors are fabricated by employing a scalable doctor blade coating technique and subsequently spray coating a layer of a small flake MXene dispersion.Hydrophilic redox-active galleries of MXenes are capable of intercalating a variety of aqueous cations including Na+,K+,and Mg2+ions,showing volumetric capacitances up to 250 F cm-3.As a result,a salt removal capacity of 39 mg g-1 with decent cycling stability is achieved.This study opens new avenues for developing freestanding,binder-and additivefree MXene electrodes for HCDI applications.展开更多
The availability of materials determines progress in engineering;those with superior,novel properties enable new technologies.Light and strong carbon fibers changed the aerospace and sports equipment fields,and zeolit...The availability of materials determines progress in engineering;those with superior,novel properties enable new technologies.Light and strong carbon fibers changed the aerospace and sports equipment fields,and zeolites with controlled porosity led to disruptive changes in the petrochemical industry.展开更多
Two-dimensional(2D)transition metal carbides,nitrides or carbonitrides(MXene)have attracted tremendous attention as a potentially the largest family of inorganic materials.They have a general formula Mn+1XnTx,where M ...Two-dimensional(2D)transition metal carbides,nitrides or carbonitrides(MXene)have attracted tremendous attention as a potentially the largest family of inorganic materials.They have a general formula Mn+1XnTx,where M is an early transition metal(2 or more can be present in a random mix or a specific order),X is C and/or N elements(oxygen can partially substitute),and T_(x)(x is variable)represent surface terminations,which can include reactive end groups(such as–OH and=O),halogens and chalcogens,and n can vary from 1 to 4(fractions are possible).All MXenes can either be produced as multilayer particles(ml-MXene)or delaminated(d-MXene)single-layer flakes.展开更多
Carbide-derived carbon （CDC） is a form of carbon produced by reacting metal carbides, such as SiC or TiC, with halogens at temperatures high enough to produce fast kinetics, but too low to permit the rearrangement o...Carbide-derived carbon （CDC） is a form of carbon produced by reacting metal carbides, such as SiC or TiC, with halogens at temperatures high enough to produce fast kinetics, but too low to permit the rearrangement of the carbon atoms into an equilibrium graphitic structure. The structure of CDC is derivative of the original carbide structure and contains nanoscale porosity and both sp2 and sp3 bonded carbon in a variety of nanoscale structures. CDC can be produced as a thin film on hard carbides to improve their tribological performance. CDC coatings are distinguished by their low friction coefficients and high wear resistance in many important industrial environments and by their resistance to spallation and delamination. The tribology of CDC coatings on SiC surfaces is described in detail.展开更多
It is essential to develop a methanol gas sensor with high selectivity and low working temperature for human health and environmental monitoring.In this work,a blend of PEDOT:PSS and Ti3C2Tx with the mass ratio of 4:1...It is essential to develop a methanol gas sensor with high selectivity and low working temperature for human health and environmental monitoring.In this work,a blend of PEDOT:PSS and Ti3C2Tx with the mass ratio of 4:1 is used to fabricate a methanol gas sensor.It possesses a high response ratio of the largest response and the second largest response(5.54)and an enhanced response compared to pure PEDOT:PSS and pure Ti3C2Tx tested at room temperature.These findings may pave the way towards design of the MXenes based high-performance gas-sensing materials in the future.展开更多
The structural and compositional variety combined with tunable surface characteristics have rendered MXenes as one of the most versatile 2D material families with numerous rapidly expanding application domains.MXenes ...The structural and compositional variety combined with tunable surface characteristics have rendered MXenes as one of the most versatile 2D material families with numerous rapidly expanding application domains.MXenes are typically synthesized by selective etching of layered carbide and nitride precursors,such as MAX phases,which have the general formula Mn+1AXn(n=1-4),where M is an early transition metal.展开更多
MXenes have shown record-breaking redox capacitance in aqueous electrolytes,but in a limited voltage window due to oxidation under anodic potential and hydrogen evolution under high cathodic potential.Coupling Ti3C2Tx...MXenes have shown record-breaking redox capacitance in aqueous electrolytes,but in a limited voltage window due to oxidation under anodic potential and hydrogen evolution under high cathodic potential.Coupling Ti3C2Tx Xene negative electrode with RuO_(2) or carbon-based positive electrodes expanded the voltage window in sulfuric acid electrolyte to about 1.5 V.Here,we present an asymmetric pseudocapacitor using abundant and eco-friendly vanadium doped MnO_(2) as the positive and Ti_(3)C_(2)Tx MXene as the negative electrode in a neutral 1M Li2SO4 electrolyte.This all-pseudocapacitive asymmetric device not only uses a safer electrolyte and is a much less expensive counter-electrode than RuO_(2),but also can operate within a 2.1 V voltage window,leading to a maximum energy density of 46 Wh/kg.This study also demonstrates the possibility of using MXene electrodes to expand the working voltage window of traditional redox-capable materials.展开更多
We previously demonstrated that octadecylamine-functionalized nanodiamond(ND-ODA)and dexamethasone(Dex)-adsorbed ND-ODA(ND-ODA–Dex)promoted anti-inflammatory and proregenerative behavior in human macrophages in vitro...We previously demonstrated that octadecylamine-functionalized nanodiamond(ND-ODA)and dexamethasone(Dex)-adsorbed ND-ODA(ND-ODA–Dex)promoted anti-inflammatory and proregenerative behavior in human macrophages in vitro.In this study,we performed a pilot study to investigate if these immunomodulatory effects translate when used as a treatment for rheumatoid arthritis in mice.Following local injection in limbs of mice with collagen type II-induced arthritis,microcomputed tomography showed that mice treated with a low dose of ND-ODA and ND-ODA–Dex did not experience bone loss to the levels observed in non-treated arthritic controls.A low dose of ND-ODA and ND-ODA–Dex also reduced macrophage infiltration and expression of proinflammatory mediators iNOS and tumor necrosis factor-a compared to the arthritic control,while a high dose of ND-ODA increased expression of these markers.Overall,these results suggest that ND-ODA may be useful as an inherently immunomodulatory platform,and support the need for an in-depth study,especially with respect to the effects of dose.展开更多
基金supported by financial support from the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIT)(NRF-2020R1A3B2079803 and NRF2019K1A3A1A21032033),Republic of Korea。
文摘Despite the safety,low cost,and high theoretical capacity(820 mA h g^(-1))of Zn metal anodes,the practical application of aqueous Zn metal batteries remains a critical challenge due to the Zn dendrite growth,corrosion,and hydrogen evolution reaction.Herein,we demonstrate the MXene ink hosting Zn metal anodes(MX@Zn)for high-performance and patternable Zn metal full batteries.The as-designed MX@Zn electrode is more facile and reversible than bare Zn and CC@Zn,as verified by better cyclic stability and lower overpotentials of symmetric cells with the plating capacity of 0.05 mA h cm^(-2)at 0.1 m A cm^(-2)and of 1 m A h cm^(-2)at 1 m A cm^(-2).The MX@Zn|MnO_(2)full cells deliver a high specific capacity of 281.9 m A h g^(-1),91.5%of the theoretical capacity,achieving 50%capacity retention from 60 mA g^(-1)to 300 mA g^(-1)and 79.7%of initial capacity after 200 cycles.Moreover,the patterned devices based on the MX@Zn electrode achieve high energy and power densities of 348.57 Wh kg^(-1)and 1556 W kg^(-1),respectively,along with a capacity retention of 64%and Coulombic efficiency of 99%over 500 cycles.The high performance of MX@Zn is attributed to the high electrical conductivity and hydrophilicity of MXene and rapid ion diffusion through the 3D interconnected porous channels.
基金supported by the Fluid Interface Reacions and Transport(FIRST)Centeran Energy Frontier Research Center supported by the U.S.Department of Energy,Office of Science,Basic Energy Sciences+1 种基金Synthesis,XRD,and SEM characterization of α-MoO_(3) were supported as a part of the Center for Mesoscale Transport PropertiesEnergy Frontier Research Center supported by the U.S.Department of Energy,Office of Science,Basic Energy Sciences,under award#DE-SC0012673
文摘While transition-metal oxides such as α-MoO_(3)provide high capacity,their use is limited by modest electronic conductivity and electrochemical instability in aqueous electrolytes.Two-dimensional(2D)MXenes,offer metallic conductivity,but their capacitance is limited in aqueous electrolytes.Insertion of partially solvated cations into Ti_(3)C_(2)MXene from lithium-based water-in-salt(WIS)electrolytes enables charge storage at positive potentials,allowing a wider potential window and higher capacitance.Herein,we demonstrate that α-MoO_(3)/Ti_(3)C_(2)hybrids combine the high capacity of α-MoO_(3)and conductivity of Ti_(3)C_(2)in WIS(19.8 m LiCI)electrolyte in a wide1.8 V voltage window.Cyclic voltammograms reveal multiple redox peaks from α-MoO_(3)in addition to the well-separated peaks of Ti_(3)C_(2)in the hybrid electrode.This leads to a higher specific charge and a higher rate capability compared to a carbon and binder containing α-MoO_(3)electrode.These results demonstrate that the addition of MXene to less conductive oxides eliminates the need for conductive carbon additives and binders,leads to a larger amount of charge stored,and increases redox capacity at higher rates.In addition,MXene encapsulated α-MoO_(3)showed improved electrochemical stability,which was attributed to the suppressed dissolution of α-MoO_(3).The work suggests that oxide/MXene hybrids are promising for energy storage.
基金financially supported by the National Key Research and Development Program of China(2017YFB0102204)the National Natural Science Foundation of China(NSFC,51572011).
文摘MXene nanosheets have been used for preparing highly flexible integrated electrodes due to their two-dimensional(2D)morphology,flexibility,high conductivity,and abundant functional groups.However,restacking of 2D nanosheets inhibits the ion transport in MXene electrodes,limiting their thickness,rate performance,and energy storage capacity.Here,we employed a natural sedimentation method instead of the conventional vacuum-assisted filtration to prepare flexible Ti3C2TxMXene films with enlarged interlayer spacing,which facilitates the access of the lithium ions to the interlayers and thus leads to a greatly enhanced electrochemical performance.The naturally sedimented flexible film shows a double lithium storage capacity compared to the conventional vacuum-filtered MXene film,along with improved rate performance and excellent cycle stability.
基金financial support from Qatar National Research Fund(a member of Qatar Foundation)through the NPRP Grant#9-254-2-120Support from the National Science Foundation(CMMI-1635233)
文摘Intercalation redox materials have shown great promise for efficient water desalination due to available faradaic gallery sites.Symmetric capacitive deionization(CDI)cells previously demonstrated using MXenes were often limited in their salt adsorption capacity(SAC)and voltage window of operation.In this study,current collector-and binder-free Ti3C2Tx MXene electrode architectures are designed with porous carbon as the positive electrode to demonstrate hybrid CDI(HCDI)operation.Furthermore,MXene current collectors are fabricated by employing a scalable doctor blade coating technique and subsequently spray coating a layer of a small flake MXene dispersion.Hydrophilic redox-active galleries of MXenes are capable of intercalating a variety of aqueous cations including Na+,K+,and Mg2+ions,showing volumetric capacitances up to 250 F cm-3.As a result,a salt removal capacity of 39 mg g-1 with decent cycling stability is achieved.This study opens new avenues for developing freestanding,binder-and additivefree MXene electrodes for HCDI applications.
文摘The availability of materials determines progress in engineering;those with superior,novel properties enable new technologies.Light and strong carbon fibers changed the aerospace and sports equipment fields,and zeolites with controlled porosity led to disruptive changes in the petrochemical industry.
文摘Two-dimensional(2D)transition metal carbides,nitrides or carbonitrides(MXene)have attracted tremendous attention as a potentially the largest family of inorganic materials.They have a general formula Mn+1XnTx,where M is an early transition metal(2 or more can be present in a random mix or a specific order),X is C and/or N elements(oxygen can partially substitute),and T_(x)(x is variable)represent surface terminations,which can include reactive end groups(such as–OH and=O),halogens and chalcogens,and n can vary from 1 to 4(fractions are possible).All MXenes can either be produced as multilayer particles(ml-MXene)or delaminated(d-MXene)single-layer flakes.
文摘Carbide-derived carbon （CDC） is a form of carbon produced by reacting metal carbides, such as SiC or TiC, with halogens at temperatures high enough to produce fast kinetics, but too low to permit the rearrangement of the carbon atoms into an equilibrium graphitic structure. The structure of CDC is derivative of the original carbide structure and contains nanoscale porosity and both sp2 and sp3 bonded carbon in a variety of nanoscale structures. CDC can be produced as a thin film on hard carbides to improve their tribological performance. CDC coatings are distinguished by their low friction coefficients and high wear resistance in many important industrial environments and by their resistance to spallation and delamination. The tribology of CDC coatings on SiC surfaces is described in detail.
基金supported by the National Natural Science Foundation of China(No.51602035)State Scholarship Fund of China,Liaoning Provincial Natural Science Foundation of China(No.20180510036)the Fundamental Research Funds for the Central Universities(No.DUT19JC41)。
文摘It is essential to develop a methanol gas sensor with high selectivity and low working temperature for human health and environmental monitoring.In this work,a blend of PEDOT:PSS and Ti3C2Tx with the mass ratio of 4:1 is used to fabricate a methanol gas sensor.It possesses a high response ratio of the largest response and the second largest response(5.54)and an enhanced response compared to pure PEDOT:PSS and pure Ti3C2Tx tested at room temperature.These findings may pave the way towards design of the MXenes based high-performance gas-sensing materials in the future.
文摘The structural and compositional variety combined with tunable surface characteristics have rendered MXenes as one of the most versatile 2D material families with numerous rapidly expanding application domains.MXenes are typically synthesized by selective etching of layered carbide and nitride precursors,such as MAX phases,which have the general formula Mn+1AXn(n=1-4),where M is an early transition metal.
基金supported by the National Natural Science Foundation of China(Nos.51972124,51902115,and 51872101)supported by King Abdullah University of Science and Technology(KAUST)under the KAUST-Drexel Competitive Research Grant(No.OSR-CRG2016-2963 sub 11206).
文摘MXenes have shown record-breaking redox capacitance in aqueous electrolytes,but in a limited voltage window due to oxidation under anodic potential and hydrogen evolution under high cathodic potential.Coupling Ti3C2Tx Xene negative electrode with RuO_(2) or carbon-based positive electrodes expanded the voltage window in sulfuric acid electrolyte to about 1.5 V.Here,we present an asymmetric pseudocapacitor using abundant and eco-friendly vanadium doped MnO_(2) as the positive and Ti_(3)C_(2)Tx MXene as the negative electrode in a neutral 1M Li2SO4 electrolyte.This all-pseudocapacitive asymmetric device not only uses a safer electrolyte and is a much less expensive counter-electrode than RuO_(2),but also can operate within a 2.1 V voltage window,leading to a maximum energy density of 46 Wh/kg.This study also demonstrates the possibility of using MXene electrodes to expand the working voltage window of traditional redox-capable materials.
基金the National Institutes of Health grant R01 HL130037.A.P.was supported by Whitaker International and David L.Boren fellowships.
文摘We previously demonstrated that octadecylamine-functionalized nanodiamond(ND-ODA)and dexamethasone(Dex)-adsorbed ND-ODA(ND-ODA–Dex)promoted anti-inflammatory and proregenerative behavior in human macrophages in vitro.In this study,we performed a pilot study to investigate if these immunomodulatory effects translate when used as a treatment for rheumatoid arthritis in mice.Following local injection in limbs of mice with collagen type II-induced arthritis,microcomputed tomography showed that mice treated with a low dose of ND-ODA and ND-ODA–Dex did not experience bone loss to the levels observed in non-treated arthritic controls.A low dose of ND-ODA and ND-ODA–Dex also reduced macrophage infiltration and expression of proinflammatory mediators iNOS and tumor necrosis factor-a compared to the arthritic control,while a high dose of ND-ODA increased expression of these markers.Overall,these results suggest that ND-ODA may be useful as an inherently immunomodulatory platform,and support the need for an in-depth study,especially with respect to the effects of dose.
