High-performance graphite materials have important roles in aerospace and nuclear reactor technologies because of their outstanding chemical stability and high-temperature performance.Their traditional production meth...High-performance graphite materials have important roles in aerospace and nuclear reactor technologies because of their outstanding chemical stability and high-temperature performance.Their traditional production method relies on repeated impregnation-carbonization and graphitization,and is plagued by lengthy preparation cycles and high energy consumption.Phase transition-assisted self-pressurized selfsintering technology can rapidly produce high-strength graphite materials,but the fracture strain of the graphite materials produced is poor.To solve this problem,this study used a two-step sintering method to uniformly introduce micro-nano pores into natural graphite-based bulk graphite,achieving improved fracture strain of the samples without reducing their density and mechanical properties.Using natural graphite powder,micron-diamond,and nano-diamond as raw materials,and by precisely controlling the staged pressure release process,the degree of diamond phase transition expansion was effectively regulated.The strain-to-failure of the graphite samples reached 1.2%,a 35%increase compared to samples produced by fullpressure sintering.Meanwhile,their flexural strength exceeded 110 MPa,and their density was over 1.9 g/cm^(3).The process therefore produced both a high strength and a high fracture strain.The interface evolution and toughening mechanism during the two-step sintering process were investigated.It is believed that the micro-nano pores formed have two roles:as stress concentrators they induce yielding by shear and as multi-crack propagation paths they significantly lengthen the crack propagation path.The two-step sintering phase transition strategy introduces pores and provides a new approach for increasing the fracture strain of brittle materials.展开更多
CeO_(2) based semiconductor are widely used in solar-driven photothermal catalytic dry reforming of methane(DRM)reaction,but still suffer from low activity and low light utilization efficiency.This study developed gra...CeO_(2) based semiconductor are widely used in solar-driven photothermal catalytic dry reforming of methane(DRM)reaction,but still suffer from low activity and low light utilization efficiency.This study developed graphite-CeO_(2) interfaces to enhance solar-driven photothermal catalytic DRM.Compared with carbon nanotubes-modified CeO_(2)(CeO_(2)-CNT),graphite-modified CeO_(2)(CeO_(2)-GRA)constructed graphite-CeO_(2) interfaces with distortion in CeO_(2),leading to the formation abundant oxygen vacancies.These graphite-CeO_(2) interfaces with oxygen vacancies enhanced optical absorption and promoted the generation and separation of photogenerated carriers.The high endothermic capacity of graphite elevated the catalyst surface temperature from 592.1−691.3℃,boosting light-to-thermal conversion.The synergy between photogenerated carriers and localized heat enabled Ni/CeO_(2)-GRA to achieve a CO production rate of 9985.6 mmol/(g·h)(vs 7192.4 mmol/(g·h)for Ni/CeO_(2))and a light-to-fuel efficiency of 21.8%(vs 13.8%for Ni/CeO_(2)).This work provides insights for designing graphite-semiconductor interfaces to advance photothermal catalytic efficiency.展开更多
The advancement of planar micro-supercapacitors(PMSCs)for micro-electromechanical systems(MEMS)has been significantly hindered by the challenge of achieving high energy and power densities.This study addresses this is...The advancement of planar micro-supercapacitors(PMSCs)for micro-electromechanical systems(MEMS)has been significantly hindered by the challenge of achieving high energy and power densities.This study addresses this issue by leveraging screen-printing technology to fabricate high-performance PMSCs using innovative composite ink.The ink,a synergistic blend of few-layer graphene(Gt),carbon black(CB),and NiCo_(2)O_(4),was meticulously mixed to form a conductive and robust coating that enhanced the capacitive performance of the PMSCs.The optimized ink formulation and printing process result in a micro-supercapacitor with an exceptional areal capacitance of 18.95 mF/cm^(2)and an areal energy density of 2.63μW·h/cm^(2)at a current density of 0.05 mA/cm^(2),along with an areal power density of 0.025 mW/cm^(2).The devices demonstrated impressive durability with a capacitance retention rate of 94.7%after a stringent 20000-cycle test,demonstrating their potential for long-term applications.Moreover,the PMSCs displayed excellent mechanical flexibility,with a capacitance decrease of only 3.43%after 5000 bending cycles,highlighting their suitability for flexible electronic devices.The ease of integrating these PMSCs into series and parallel configurations for customized power further underscores their practicality for integrated power supply solutions in various technologies.展开更多
The expanded graphite (EG) with a low density and better extinction performance can be used in military as passive jamming material in IR and MMW bands. Its complex refractive index is a significant parameter for the ...The expanded graphite (EG) with a low density and better extinction performance can be used in military as passive jamming material in IR and MMW bands. Its complex refractive index is a significant parameter for the extinction property. This paper presents a method to calculate the complex refractive index of EG. The reflection spectra of EG pellets were measured in the 0.24-2.6μm and 2.5-25μm bands, respectively. Based on the measurement results, the complex refractive index of EG in 5-10μm band was calculated by using Kramers-Kronig(K-K) relation and Bruggeman effective medium theory, and then the errors were analyzed. The results indicate that it is feasible to calculate the complex refractive index of EG based on its IR reflection spectra data.展开更多
Cycling and rate performance of natural graphite is still limited by the sluggish kinetics of lithium ions,which can be improved by surface modifications in previous research.Among these methods,amorphous carbon coati...Cycling and rate performance of natural graphite is still limited by the sluggish kinetics of lithium ions,which can be improved by surface modifications in previous research.Among these methods,amorphous carbon coating has been proved to be mature and efficient.However,the significance of coating uniformity in relation to solid electrolyte interphase(SEI)has been largely overlooked.In this study,the uniformity of amorphous carbon coating is adjusted by the particle size of pitch.When discharged-charged at 1 C,graphite half-cells with such uniform coating show 90.3%of the capacity at 0.1 C,while that is 82.1%for non-uniform coating.Additionally,improved initial coulombic efficiency and cycling stability are demonstrated.These can be attributed to graphite anodes featuring a uniform carbon coating that promotes effective and homogeneous LiF formation within the inorganic matrix.This leads to the establishment of a stabilized SEI,confirmed by time-of-flight secondary ion mass spectrometry(TOF-SIMS).This work provides valuable reference into the rational control of graphite interfaces for high electrochemical performance.展开更多
By using hydrothermal synthesis method, successively adding tetrabutyl titanate and expandable flake graphite in 40 mL 0.95% NH4Cl solution prepared the nano TiO2/expandable flake graphite, which was then settled in m...By using hydrothermal synthesis method, successively adding tetrabutyl titanate and expandable flake graphite in 40 mL 0.95% NH4Cl solution prepared the nano TiO2/expandable flake graphite, which was then settled in muffle furnace in the expansion of 10 s under 800 ℃ and got nanosized TiO2/expanded graphite. Synthesized that with CoFe2O4 by chemical coprecipitation method finally prepared magnetic nanosized photocatalyst TiO2/expanded graphite. Magnetic nanosized TiO2/expanded graphite was studied on the photodegradation performance of methyl orange solution and the magnetic recovery after the degradation of methyl orange solution. The experiment result showed that in 50 mL 25 mg/L methyl orange solution joined 120 mg loading 50% TiO2 of the expanded graphite, exposed to ultraviolet irradiation for 1 h, the methyl orange decolorization ratio was 90%. When the load of CoFe2O4 in nanosized TiO2/expanded graphite reached 40%, its magnetic recovery efficiency reached 94.3%.展开更多
Graphitic carbon nitride(g-C_(3)N_(4))exhibits great mechanical as well as thermal characteristics,making it a valuable ma-terial for use in photoelectric conversion devices,an accelerator for synthesis of organic com...Graphitic carbon nitride(g-C_(3)N_(4))exhibits great mechanical as well as thermal characteristics,making it a valuable ma-terial for use in photoelectric conversion devices,an accelerator for synthesis of organic compounds,an electrolyte for fuel cell applications or power sources,and a hydrogen storage substance and a fluorescence detector.It is fabricated using dif-ferent methods,and there is a variety of morphologies and nanostructures such as zero to three dimensions that have been designed for different purposes.Ther e are many reports about g-C_(3)N_(4) in recent years,but a comprehensive review which covers nanostructure dimensions and their properties are missing.This review paper aims to give basic and comprehensive understanding of the photocatalytic and electrocatalytic usages of g-C_(3)N_(4).It highlights the recent progress of g-C_(3)N_(4) nano-structure designing by covering synthesis methods,dimensions,morphologies,applications and properties.Along with the summary,we will also discuss the challenges and prospects.Scientists,investigators,and engineers looking at g-C_(3)N_(4) nanostructures for a variety of applications might find our review paper to be a useful resource.展开更多
Graphite is naturally floatable due to its hydrophobic pro pe rty and also soft and smears on other gangue particles, rendering the gangue mor e or less floatable too. Due to this reason it is important to concentrate...Graphite is naturally floatable due to its hydrophobic pro pe rty and also soft and smears on other gangue particles, rendering the gangue mor e or less floatable too. Due to this reason it is important to concentrate on ar eas such as suitable flotation reagents, depression agents, pH modifiers, and pa rticle size to be fed during the process. The paper surveys and analyses the sui table particle size to be fed to achieve high-grade concentrate. According to t h e work carried out the author suggested the ideal cost effective flotation f low sheet for improved results at Bogala Mines in Sri Lanka.展开更多
A dense ZrC coating with the thickness of 130 μm is prepared on graphite by reactive melt infiltration.XRD and SEM analyses show that the phase composition of the coating is ZrC and it adheres well with the substrate...A dense ZrC coating with the thickness of 130 μm is prepared on graphite by reactive melt infiltration.XRD and SEM analyses show that the phase composition of the coating is ZrC and it adheres well with the substrate.The influence of ZrC coating on mechanical properties of the graphite was investigated by compression tests and the results show that after the coating process,the compression strength of the coated sample is improved by 13.64% as compared with graphite sample.The improvement of the compression strength for ZrC coated sample can be associated to the increased density and the ZrC particle reinforcement due to the infiltration and reaction of the melted Zr with carbon substrate in the coating process.展开更多
Graphite oxide(GO) was prepared by the pressurized oxidation method and incorporated into polyimide(PI) matrix to fabricate high-k composite films by in-situ polymerization and subsequent thermal treatment. The result...Graphite oxide(GO) was prepared by the pressurized oxidation method and incorporated into polyimide(PI) matrix to fabricate high-k composite films by in-situ polymerization and subsequent thermal treatment. The results show that the as-prepared GO had good dispersion and compatibility in PI matrix due to the introduction of abundant oxygen-containing functional groups during the oxidation. The residual graphitic domains and the thermal treatment induced reduction of GO further enhanced the dielectric permittivity of the resulting GO–PI composites. The dielectric permittivity of the GO–PI composites exhibited a typical percolation behavior with a percolation threshold of 0.0347 of volume ratio and a critical exponent of 0.837. Near the percolation threshold, the dielectric permittivity of the GO–PI composite increased to 108 at 10~2 Hz and was 26 times that of the pure PI.展开更多
A novel polyaniline-graphite composite film glucose oxidase （PGCF GOD） electrode was developed. The PGCF was synthesized by cyclic voitammetry method in 0.5 mol/L H2SO4 solution containing 1 g/L graphite powder and ...A novel polyaniline-graphite composite film glucose oxidase （PGCF GOD） electrode was developed. The PGCF was synthesized by cyclic voitammetry method in 0.5 mol/L H2SO4 solution containing 1 g/L graphite powder and 0.2 mol/L aniline. The PGCF GOD electrode was prepared by doping GOD into the composite film. The morphology of the PGCF and the response property of the PGCF GOD electrode were investigated by scanning electron microscopy and electrochemical measurement, respectively. The results show that the PGCF has a porous and netty structure and the PGCF GOD electrode has excellent response property such as high sensitivity and short response time. Influences of pH value, temperature, glucose concentration and potential on the response current of the electrode were also discussed. The sensor has a maximum steady-state current density of 357.17μA/cm2 and an apparent Michaelis-Menten constant of 16.57 mmol/L. The maximum current response of the enzyme electrode occurs under the condition ofpH 5.5, 0.8 V and 65℃.展开更多
The graphite was modified by mild oxidation, and the effects of modification temperature and soaking time on the characteristics of graphite were investigated. The structure and characteristics of the graphite were de...The graphite was modified by mild oxidation, and the effects of modification temperature and soaking time on the characteristics of graphite were investigated. The structure and characteristics of the graphite were determined by X-ray diffraction, scanning electron microscopy, BET surface area, particle size analysis and electrochemical measurements. The results show that the modified graphite has a better-developed crystallite structure, larger average particle diameter, smaller surface area, and better electrochemical characteristics than the untrented graphite. The sample mild-oxidized at 600℃ for 3h has the best electrochemical performances with a reversible capacity of 304.5mA·h/g, a irreversible capacity of 66.4mA·h/g, and a initial coulombic efficiency of 82.1%. The charge/discharge properties and a cycling stability of the prototype lithium ion batteries with modified graphite as anodes are improved. Its capacity retention ratio at the 200th cycle is enhanced from 66.75% to 90.15%.展开更多
The graphite was modified using pitch through dynamical melt-carbonization, and the effects of modification temperature and the amount of pitch on the characteristics of graphite were investigated. The structure and c...The graphite was modified using pitch through dynamical melt-carbonization, and the effects of modification temperature and the amount of pitch on the characteristics of graphite were investigated. The structure and characteristics of the graphite were determined by X-ray diffractometry(XRD), scanning electron microscopy(SEM), particle size analysis and electrochemical measurements. The results show that the modified graphite has a disordered carbon/graphite composite structure, larger average particle diameter, greater tap density, and better electrochemical characteristics than the untreated graphite. The sample coated with 10% pitch dynamical melt-carbonized at 400 ℃ for 3 h and heat-treated at 850 ℃ for 2 h has better electrochemical performances with a reversible capacity of 360.5 mA·h/g, a irreversible capacity of 41.0 mA·h/g, and an initial coulombic efficiency of 89.8% compared with natural graphite and disordered carbon. The cycling stability of the Li/C cell with modified graphite as anodes is improved, and its capacity retention ratio at the 30th cycle is up to 94.37%.展开更多
China produces the largest amount of graphite raw materials in the world and the largest amount of graphite tailings at the same time. At present, graphite tailings in China are up to 200 million tones, which not only...China produces the largest amount of graphite raw materials in the world and the largest amount of graphite tailings at the same time. At present, graphite tailings in China are up to 200 million tones, which not only occupy large area of land, cause environmental pollutions, the collapes of the tailings dam also threaten the life of local residents.展开更多
基金Natural Science Foundation of Shanghai(24ZR1400800)he Natural Science Foundation of China(U23A20685,52073058,91963204)+1 种基金the National Key R&D Program of China(2021YFB3701400)Shanghai Sailing Program(23YF1400200)。
文摘High-performance graphite materials have important roles in aerospace and nuclear reactor technologies because of their outstanding chemical stability and high-temperature performance.Their traditional production method relies on repeated impregnation-carbonization and graphitization,and is plagued by lengthy preparation cycles and high energy consumption.Phase transition-assisted self-pressurized selfsintering technology can rapidly produce high-strength graphite materials,but the fracture strain of the graphite materials produced is poor.To solve this problem,this study used a two-step sintering method to uniformly introduce micro-nano pores into natural graphite-based bulk graphite,achieving improved fracture strain of the samples without reducing their density and mechanical properties.Using natural graphite powder,micron-diamond,and nano-diamond as raw materials,and by precisely controlling the staged pressure release process,the degree of diamond phase transition expansion was effectively regulated.The strain-to-failure of the graphite samples reached 1.2%,a 35%increase compared to samples produced by fullpressure sintering.Meanwhile,their flexural strength exceeded 110 MPa,and their density was over 1.9 g/cm^(3).The process therefore produced both a high strength and a high fracture strain.The interface evolution and toughening mechanism during the two-step sintering process were investigated.It is believed that the micro-nano pores formed have two roles:as stress concentrators they induce yielding by shear and as multi-crack propagation paths they significantly lengthen the crack propagation path.The two-step sintering phase transition strategy introduces pores and provides a new approach for increasing the fracture strain of brittle materials.
文摘CeO_(2) based semiconductor are widely used in solar-driven photothermal catalytic dry reforming of methane(DRM)reaction,but still suffer from low activity and low light utilization efficiency.This study developed graphite-CeO_(2) interfaces to enhance solar-driven photothermal catalytic DRM.Compared with carbon nanotubes-modified CeO_(2)(CeO_(2)-CNT),graphite-modified CeO_(2)(CeO_(2)-GRA)constructed graphite-CeO_(2) interfaces with distortion in CeO_(2),leading to the formation abundant oxygen vacancies.These graphite-CeO_(2) interfaces with oxygen vacancies enhanced optical absorption and promoted the generation and separation of photogenerated carriers.The high endothermic capacity of graphite elevated the catalyst surface temperature from 592.1−691.3℃,boosting light-to-thermal conversion.The synergy between photogenerated carriers and localized heat enabled Ni/CeO_(2)-GRA to achieve a CO production rate of 9985.6 mmol/(g·h)(vs 7192.4 mmol/(g·h)for Ni/CeO_(2))and a light-to-fuel efficiency of 21.8%(vs 13.8%for Ni/CeO_(2)).This work provides insights for designing graphite-semiconductor interfaces to advance photothermal catalytic efficiency.
基金supported by the Shanxi Province Central Guidance Fund for Local Science and Technology Development Project(YDZJSX2024D030)the National Natural Science Foundation of China(22075197,22278290)+2 种基金the Shanxi Province Key Research and Development Program Project(2021020660301013)the Shanxi Provincial Natural Science Foundation of China(202103021224079)the Research and Development Project of Key Core and Common Technology of Shanxi Province(20201102018).
文摘The advancement of planar micro-supercapacitors(PMSCs)for micro-electromechanical systems(MEMS)has been significantly hindered by the challenge of achieving high energy and power densities.This study addresses this issue by leveraging screen-printing technology to fabricate high-performance PMSCs using innovative composite ink.The ink,a synergistic blend of few-layer graphene(Gt),carbon black(CB),and NiCo_(2)O_(4),was meticulously mixed to form a conductive and robust coating that enhanced the capacitive performance of the PMSCs.The optimized ink formulation and printing process result in a micro-supercapacitor with an exceptional areal capacitance of 18.95 mF/cm^(2)and an areal energy density of 2.63μW·h/cm^(2)at a current density of 0.05 mA/cm^(2),along with an areal power density of 0.025 mW/cm^(2).The devices demonstrated impressive durability with a capacitance retention rate of 94.7%after a stringent 20000-cycle test,demonstrating their potential for long-term applications.Moreover,the PMSCs displayed excellent mechanical flexibility,with a capacitance decrease of only 3.43%after 5000 bending cycles,highlighting their suitability for flexible electronic devices.The ease of integrating these PMSCs into series and parallel configurations for customized power further underscores their practicality for integrated power supply solutions in various technologies.
文摘The expanded graphite (EG) with a low density and better extinction performance can be used in military as passive jamming material in IR and MMW bands. Its complex refractive index is a significant parameter for the extinction property. This paper presents a method to calculate the complex refractive index of EG. The reflection spectra of EG pellets were measured in the 0.24-2.6μm and 2.5-25μm bands, respectively. Based on the measurement results, the complex refractive index of EG in 5-10μm band was calculated by using Kramers-Kronig(K-K) relation and Bruggeman effective medium theory, and then the errors were analyzed. The results indicate that it is feasible to calculate the complex refractive index of EG based on its IR reflection spectra data.
基金Project(52377220)supported by the National Natural Science Foundation of ChinaProject(kq2208265)supported by the Natural Science Foundation of Changsha,Hunan Province,ChinaProject supported by State Key Laboratory of Powder Metallurgy(Central South University,Changsha,China)。
文摘Cycling and rate performance of natural graphite is still limited by the sluggish kinetics of lithium ions,which can be improved by surface modifications in previous research.Among these methods,amorphous carbon coating has been proved to be mature and efficient.However,the significance of coating uniformity in relation to solid electrolyte interphase(SEI)has been largely overlooked.In this study,the uniformity of amorphous carbon coating is adjusted by the particle size of pitch.When discharged-charged at 1 C,graphite half-cells with such uniform coating show 90.3%of the capacity at 0.1 C,while that is 82.1%for non-uniform coating.Additionally,improved initial coulombic efficiency and cycling stability are demonstrated.These can be attributed to graphite anodes featuring a uniform carbon coating that promotes effective and homogeneous LiF formation within the inorganic matrix.This leads to the establishment of a stabilized SEI,confirmed by time-of-flight secondary ion mass spectrometry(TOF-SIMS).This work provides valuable reference into the rational control of graphite interfaces for high electrochemical performance.
文摘By using hydrothermal synthesis method, successively adding tetrabutyl titanate and expandable flake graphite in 40 mL 0.95% NH4Cl solution prepared the nano TiO2/expandable flake graphite, which was then settled in muffle furnace in the expansion of 10 s under 800 ℃ and got nanosized TiO2/expanded graphite. Synthesized that with CoFe2O4 by chemical coprecipitation method finally prepared magnetic nanosized photocatalyst TiO2/expanded graphite. Magnetic nanosized TiO2/expanded graphite was studied on the photodegradation performance of methyl orange solution and the magnetic recovery after the degradation of methyl orange solution. The experiment result showed that in 50 mL 25 mg/L methyl orange solution joined 120 mg loading 50% TiO2 of the expanded graphite, exposed to ultraviolet irradiation for 1 h, the methyl orange decolorization ratio was 90%. When the load of CoFe2O4 in nanosized TiO2/expanded graphite reached 40%, its magnetic recovery efficiency reached 94.3%.
基金M Tahir is funded by EU H2020 Marie Skłodows-ka-Curie Fellowship(1439425).
文摘Graphitic carbon nitride(g-C_(3)N_(4))exhibits great mechanical as well as thermal characteristics,making it a valuable ma-terial for use in photoelectric conversion devices,an accelerator for synthesis of organic compounds,an electrolyte for fuel cell applications or power sources,and a hydrogen storage substance and a fluorescence detector.It is fabricated using dif-ferent methods,and there is a variety of morphologies and nanostructures such as zero to three dimensions that have been designed for different purposes.Ther e are many reports about g-C_(3)N_(4) in recent years,but a comprehensive review which covers nanostructure dimensions and their properties are missing.This review paper aims to give basic and comprehensive understanding of the photocatalytic and electrocatalytic usages of g-C_(3)N_(4).It highlights the recent progress of g-C_(3)N_(4) nano-structure designing by covering synthesis methods,dimensions,morphologies,applications and properties.Along with the summary,we will also discuss the challenges and prospects.Scientists,investigators,and engineers looking at g-C_(3)N_(4) nanostructures for a variety of applications might find our review paper to be a useful resource.
文摘制备了二氧化锰复合石墨(MnO2@graphite)电极,通过XRD,TEM对电极材料进行表征,并通过电化学工作系统(循环伏安法,线性扫描伏安法,计时电量法)对MnO2@graphite电极的电催化机理进行了研究。以有机染料罗丹明B(Rhodamine B,RhB)和2,4-二氯苯酚(2,4-DCP)为对象,探讨了pH7.0中性条件下其类电Fenton降解的电催化性能。对1.0×10-5 mol/LRhB在外加电压6 V和支持电解质Na2SO4 10g/L条件下,类电Fenton反应120 min,RhB降解率达100%。通过紫外-可见吸收光谱(UV-vis)、红外光谱、总有机碳(TOC)测定等方法,研究了类电Fenton体系深度氧化降解RhB特性。结果表明,4 h RhB矿化率可达67.6%,同样条件下,7 h 2,4-DCP矿化率达到84.9%。同时,采用辣根过氧化物酶催化反应吸光光度法和苯甲酸荧光分析法分别分析测定RhB降解反应过程中H2O2和羟基自由基(.OH)的量,表明有机物的降解涉及.OH历程。
文摘Graphite is naturally floatable due to its hydrophobic pro pe rty and also soft and smears on other gangue particles, rendering the gangue mor e or less floatable too. Due to this reason it is important to concentrate on ar eas such as suitable flotation reagents, depression agents, pH modifiers, and pa rticle size to be fed during the process. The paper surveys and analyses the sui table particle size to be fed to achieve high-grade concentrate. According to t h e work carried out the author suggested the ideal cost effective flotation f low sheet for improved results at Bogala Mines in Sri Lanka.
基金Project(51304249)supported by the National Natural Science Foundation of ChinaProject(14JJ3023)supported by Hunan Provincial Science Foundation of China+3 种基金Project(2011CB605801)supported by the National Basic Research Program of ChinaProjects(2012M511752,2013T607767)supported by the China Postdoctoral Science FoundationProject(2012QNZT004)supported by the Fundamental Research Funds for the Central Universities of ChinaProject supported by the Freedom Explore Program of Central South University,China
文摘A dense ZrC coating with the thickness of 130 μm is prepared on graphite by reactive melt infiltration.XRD and SEM analyses show that the phase composition of the coating is ZrC and it adheres well with the substrate.The influence of ZrC coating on mechanical properties of the graphite was investigated by compression tests and the results show that after the coating process,the compression strength of the coated sample is improved by 13.64% as compared with graphite sample.The improvement of the compression strength for ZrC coated sample can be associated to the increased density and the ZrC particle reinforcement due to the infiltration and reaction of the melted Zr with carbon substrate in the coating process.
基金Project(2013JSJJ002)supported by the Faculty Research Fund of Central South University,China
文摘Graphite oxide(GO) was prepared by the pressurized oxidation method and incorporated into polyimide(PI) matrix to fabricate high-k composite films by in-situ polymerization and subsequent thermal treatment. The results show that the as-prepared GO had good dispersion and compatibility in PI matrix due to the introduction of abundant oxygen-containing functional groups during the oxidation. The residual graphitic domains and the thermal treatment induced reduction of GO further enhanced the dielectric permittivity of the resulting GO–PI composites. The dielectric permittivity of the GO–PI composites exhibited a typical percolation behavior with a percolation threshold of 0.0347 of volume ratio and a critical exponent of 0.837. Near the percolation threshold, the dielectric permittivity of the GO–PI composite increased to 108 at 10~2 Hz and was 26 times that of the pure PI.
基金Projects(50473022, 20673036) supported by the National Natural Science Foundation of China project(2005) supported by the State Key Laboratory of Chemo/Biosensing and Chemometrics of China+1 种基金 project(2006FJ4100) supported by the Science Technology Project of Hunan Province project(2006) supported by the Postdoctor Foundation of Hunan University
文摘A novel polyaniline-graphite composite film glucose oxidase （PGCF GOD） electrode was developed. The PGCF was synthesized by cyclic voitammetry method in 0.5 mol/L H2SO4 solution containing 1 g/L graphite powder and 0.2 mol/L aniline. The PGCF GOD electrode was prepared by doping GOD into the composite film. The morphology of the PGCF and the response property of the PGCF GOD electrode were investigated by scanning electron microscopy and electrochemical measurement, respectively. The results show that the PGCF has a porous and netty structure and the PGCF GOD electrode has excellent response property such as high sensitivity and short response time. Influences of pH value, temperature, glucose concentration and potential on the response current of the electrode were also discussed. The sensor has a maximum steady-state current density of 357.17μA/cm2 and an apparent Michaelis-Menten constant of 16.57 mmol/L. The maximum current response of the enzyme electrode occurs under the condition ofpH 5.5, 0.8 V and 65℃.
基金Project (2002 87) surported by Key Problem Study Plan of Science and Technology of Hunan Province
文摘The graphite was modified by mild oxidation, and the effects of modification temperature and soaking time on the characteristics of graphite were investigated. The structure and characteristics of the graphite were determined by X-ray diffraction, scanning electron microscopy, BET surface area, particle size analysis and electrochemical measurements. The results show that the modified graphite has a better-developed crystallite structure, larger average particle diameter, smaller surface area, and better electrochemical characteristics than the untrented graphite. The sample mild-oxidized at 600℃ for 3h has the best electrochemical performances with a reversible capacity of 304.5mA·h/g, a irreversible capacity of 66.4mA·h/g, and a initial coulombic efficiency of 82.1%. The charge/discharge properties and a cycling stability of the prototype lithium ion batteries with modified graphite as anodes are improved. Its capacity retention ratio at the 200th cycle is enhanced from 66.75% to 90.15%.
基金Project(50302016) supported by the National Natural Science Foundation of China
文摘The graphite was modified using pitch through dynamical melt-carbonization, and the effects of modification temperature and the amount of pitch on the characteristics of graphite were investigated. The structure and characteristics of the graphite were determined by X-ray diffractometry(XRD), scanning electron microscopy(SEM), particle size analysis and electrochemical measurements. The results show that the modified graphite has a disordered carbon/graphite composite structure, larger average particle diameter, greater tap density, and better electrochemical characteristics than the untreated graphite. The sample coated with 10% pitch dynamical melt-carbonized at 400 ℃ for 3 h and heat-treated at 850 ℃ for 2 h has better electrochemical performances with a reversible capacity of 360.5 mA·h/g, a irreversible capacity of 41.0 mA·h/g, and an initial coulombic efficiency of 89.8% compared with natural graphite and disordered carbon. The cycling stability of the Li/C cell with modified graphite as anodes is improved, and its capacity retention ratio at the 30th cycle is up to 94.37%.
文摘China produces the largest amount of graphite raw materials in the world and the largest amount of graphite tailings at the same time. At present, graphite tailings in China are up to 200 million tones, which not only occupy large area of land, cause environmental pollutions, the collapes of the tailings dam also threaten the life of local residents.
