Serving as gas diffusion layers(GDLs),the thermal conductivity of carbon paper(CP)plays a significant role in the heat transfer management in fuel cells.In the present study,the effect of graphitization degree of CP o...Serving as gas diffusion layers(GDLs),the thermal conductivity of carbon paper(CP)plays a significant role in the heat transfer management in fuel cells.In the present study,the effect of graphitization degree of CP on its through plane thermal conductivity and in-plane thermal conductivity is investigated.The relationship between heat treatment temperatures(1800,2000,2200,2400 and 2500℃)and graphitization degree is also investigated by SEM,XRD and Raman measurements.A model for CP under different graphitization degree is suggested considering the thermal conductivity difference of carbon fiber and matrix carbon.The experimental and simulation results are compared.The results show that the graphitization degree has a significant impact on the through-plane thermal conductivity and in plane thermal conductivity.展开更多
A novel carbon fiber pretreatment was proposed.Polyacrylonitrile(PAN)-based carbon fibers were first anodized in H3PO4 electrolyte to achieve an active surface,and then coated with Mo-B catalysts by immersed the carbo...A novel carbon fiber pretreatment was proposed.Polyacrylonitrile(PAN)-based carbon fibers were first anodized in H3PO4 electrolyte to achieve an active surface,and then coated with Mo-B catalysts by immersed the carbon fibers in a uniformly dispersed Mo-B sol.The as-treated carbon fibers were then graphitized at 2 400 ℃ for 2 h.The structural changes were characterized by X-ray diffractometry(XRD),Raman spectroscopy,scanning electron microscopy(SEM) and high-resolution transmission electronic microscopy(HRTEM).The results show that much better graphitization can be achieved in the presence of Mo-B,with an interlayer spacing(d002) of 0.335 8 nm and a crystalline size(Lc) of 28 nm.展开更多
Prussian blue(PB) was used as catalyst to improve the extent of graphitization of polyacrylonitrile(PAN)-based carbon fibers.PB was deposited on carbon fibers by anodic electrodeposition and the thickness of PB coatin...Prussian blue(PB) was used as catalyst to improve the extent of graphitization of polyacrylonitrile(PAN)-based carbon fibers.PB was deposited on carbon fibers by anodic electrodeposition and the thickness of PB coating(PB content) was controlled by adjusting the electrodeposition time.PAN-based carbon fibers with PB coating were heat-treated and the extent of graphitization was measured by X-ray diffractometry and Raman spectroscopy.The results indicate that the extent of graphitization of PAN-based carbon fibers is enhanced in the presence of the coating.When the PB-coated carbon fibers were heat-treated at 1 900 ℃,interlayer spacing(d002) and crystallite size(Lc) reach 0.336 8 and 21.2 nm respectively.Contrarily,the values of d002 and Lc are 0.341 4 and 7.4 nm respectively when the bare carbon fibers were heat-treated at 2 800 ℃.Compared with the bare carbon fibers,PB can make the heat treatment temperature(HTT) drop more than 500 ℃ in order to reach the same extent of graphitization.Furthermore,the research results show that PB content also has a certain influence on the extent of graphitization at the same HTT.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
Lithium-ion batteries(LIBs)are an electrochemical energy storage technology that has been widely used for portable electrical devices,electric vehicles,and grid storage,etc.To satisfy the demand for user convenience e...Lithium-ion batteries(LIBs)are an electrochemical energy storage technology that has been widely used for portable electrical devices,electric vehicles,and grid storage,etc.To satisfy the demand for user convenience especially for electric vehicles,the development of a fast-charging technology for LIBs has become a critical focus.In commercial LIBs,the slow kinetics of Li+intercalation into the graphite anode from the electrolyte solution is known as the main restriction for fast-charging.We summarize the recent advances in obtaining fast-charging graphite-based anodes,mainly involving modifications of the electrolyte solution and graphite anode.Specifically,strategies for increasing the ionic conductivity and regulating the Li+solvation/desolvation state in the electrolyte solution,as well as optimizing the fabrication and the intrinsic activity of graphite-based anodes are discussed in detail.This review considers practical ways to obtain fast Li+intercalation kinetics into a graphite anode from the electrolyte as well as analysing progress in the commercialization of fast-charging LIBs.展开更多
As an emerging electrochemical energy storage technology,potassium-ion batteries(PIBs),which are considered a“beyond Li-ion”battery system,have attracted tremendous attention due to their potential for providing a h...As an emerging electrochemical energy storage technology,potassium-ion batteries(PIBs),which are considered a“beyond Li-ion”battery system,have attracted tremendous attention due to their potential for providing a high energy density,and having abundant resource,and a low cost.However,their commercialization is hindered by the lack of practical anode materials.Among various reported anodes,conventional carbon materials,including graphite,soft carbon,and hard carbon,have emerged as promising candidates because of their abundance,low cost,high conductivity,and tunable structures.However,these materials have problems such as a low initial Coulombic efficiency,significant volume expansion,and unsatisfactory cyclability and rate performance.Various strategies to solve these have been explored,including optimizing the interlayer spacing,structural design,surface coating,constructing a multifunctional framework,and forming composites.This review provides a comprehensive overview of the recent progress in conventional carbon anodes,highlighting structural design strategies,mechanisms for improving the electrochemical performance,and underscores the critical role of these materials in promoting the practical application of PIBs.展开更多
Iron(Fe)nanoparticles and graphite(Gr)with different masses of bismuth trisulfide(Bi_(2)S_(3))were mixed by high-energy ball milling treatment to fabricate the corresponding composite iron anodes Bi_(2)S_(3)@Fe-Gr.The...Iron(Fe)nanoparticles and graphite(Gr)with different masses of bismuth trisulfide(Bi_(2)S_(3))were mixed by high-energy ball milling treatment to fabricate the corresponding composite iron anodes Bi_(2)S_(3)@Fe-Gr.The hydrogen evolution reaction and iron passivation process on these iron electrodes were investigated in alkaline and neutral solutions.The iron electrode Bi_(2)S_(3)-3@Fe-Gr(The additional amount of Bi_(2)S_(3)was 3 mg)revealed the strongest ability to inhibit hydrogen evolution among the iron electrodes of the present investigation,while the Bi_(2)S_(3)-6@Fe-Gr electrode(The additional amount of Bi_(2)S_(3)was 6 mg)delivered significant performance in inhibiting anodic passivation.This is because the high-energy ball milling process leads to the well-dispersion of Bi_(2)S_(3)and the changes in the surface of Fe nanoparticles,thereby slowing down the passivation of the iron electrode surface.展开更多
Magnesium potassium phosphate cement(MKPC)coatings exhibit potential for carbon steel protection but face challenges in practical application due to the preparation process and properties.This study develops flake gra...Magnesium potassium phosphate cement(MKPC)coatings exhibit potential for carbon steel protection but face challenges in practical application due to the preparation process and properties.This study develops flake graphite(FG)-modified MKPC coatings via spraying process,investigating the effects of FG size and dosage on phase composition,microstructure,mechanical properties,corrosion protection,and thermal conductivity.Results show that a low FG dosage(5 wt%)synergistically optimizes multifunctional performance.Compared to unmodified MKPC,FG2-1 exhibited exceptional impact resistance,associated with a 57%reduction in corrosion current density(icorr),a 356.3% increase in low-frequency impedance modulus(Z_(0.01 Hz))and a 37% increase in thermal conductivity.However,the coating with a high FG dosage(15 wt%)degraded performance due to defect accumulation and reduced crystallinity of KMgPO_(4)·6H_(2)O.This work advances the rational design of multifunctional inorganic coatings for extreme service environments requiring coupled corrosion protection and thermal management.展开更多
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
Lonsdaleite,also known as hexagonal diamond,is an allotrope of carbon with a hexagonal crystal structure,which was discovered in the nanostructure of the Canyon Diablo meteorite.Theoretical calculations have shown tha...Lonsdaleite,also known as hexagonal diamond,is an allotrope of carbon with a hexagonal crystal structure,which was discovered in the nanostructure of the Canyon Diablo meteorite.Theoretical calculations have shown that this structure gives it exceptional physical properties that exceed those of cubic diamond,making it highly promising for groundbreaking applications in superhard cutting tools,wide-bandgap semiconductor devices,and materials for extreme environments.As a result,the controllable synthesis of hexagonal diamond has emerged as a cutting-edge research focus in materials science.This review briefly outlines the progress in this area,with a focus on the mechanisms governing its key synthesis conditions,its intrinsic physical properties,and its potential applications in various fields.展开更多
Based on the service characteristics of fuel elements for molten salt reactors,they need to have a high power density,resistance to coolant infiltration,and excellent thermodynamic properties.To solve the problem of t...Based on the service characteristics of fuel elements for molten salt reactors,they need to have a high power density,resistance to coolant infiltration,and excellent thermodynamic properties.To solve the problem of the graphite used in the fuel element for these reactors being susceptible to molten salt infiltration,carbon black(CB)was added to increase the density of the graphite,and a fuel element(TRISO(tri-structural isotropic)fuel particles were randomly distributed in the modified graphite matrix)was prepared by cold isostatic pressing process.An out-of-pile performance study shows that the densification and pore structure of the modified graphite matrix were improved,as was the resistance to molten salt infiltration.The median pore size of the modified graphite was reduced from 673 to 433 nm and the threshold pressure for molten salt(FLiBe,66%(molar fraction)LiF and 34%BeF_(2))infiltration was increased from 0.88 to 1.37 MPa.The isotropic CB made the graphite matrix less anisotropic,while its thermal conductivity and compressive strength were reduced due to the difficult graphitization of CB.Fuel elements containing 20%(volume fraction)TRISO particles were prepared.Numerical simulations show that the power and temperature distribution of the fuel were in line with the design requirements.The modified graphite matrix had a higher density,smaller pores,a lower anisotropy and a greater resistance to FLiBe infiltration.展开更多
Cu suffers from oxidation and corrosion during application due to its active chemical properties.Graphene⁃modified Cu can significantly improve its stability during application.However,copper is easily sintered at hig...Cu suffers from oxidation and corrosion during application due to its active chemical properties.Graphene⁃modified Cu can significantly improve its stability during application.However,copper is easily sintered at high temperatures,so that graphene cannot be grown inside.We demonstrate two kinds of spacers,graphite and SiO_(2),which are effective in preventing the sintering of copper and are used to assist in the growth of graphene.In the Cu⁃C system,the nucleation of graphene is scarce,and it tends to nucleate and grow on the concave surface of copper first,and then grow epitaxially to the convex surface of copper.Eventually,the obtained graphene is relatively thick.In the Cu⁃SiO_(2) system,due to the oxygen released by SiO_(2) at high temperatures,the surface of copper becomes rough.This leads to an increase in the number of graphene nucleation sites without preferred orientation,and relatively thin graphene is obtained.Two different growth mechanisms have been established for spacerseffects on graphene growth.It provides insights for graphene engineering for further applications.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
Shuttle effect,poor conductivity and large volume expansion are the main factors that hinder the practical application of sulfur cathodes.Currently,rational structure designing of carbon-based sulfur hosts is the most...Shuttle effect,poor conductivity and large volume expansion are the main factors that hinder the practical application of sulfur cathodes.Currently,rational structure designing of carbon-based sulfur hosts is the most effective strategy to address the above issues.However,the preparation process of carbon-based sulfur hosts is usually complex and costly.Therefore,it is necessary to develop an efficient and cost-effective method to fabricate carbon hosts for high-performance sulfur cathodes.Herein,we reported the fabrication of a bio-derived nitrogen doped porous carbon materials(BNPC)via a molten-salt method for high performance sulfur cathodes.The long-range-ordered honeycomb structure of BNPC is favorable for the trapping of polysulfide(PS)species and accommodates the volumetric variation of sulfur during cycling,while the high graphitization degree of BNPC favors the redox kinetics of sulfur cathodes.Moreover,the nitrogen doping content not only enhances the electrical conductivity of BNPC,but also provides ample anchoring sites for the immobilization of PS,which plays a key role in suppressing the shuttle effect.As a result,the S@BNPC cathode exhibits a high initial specific capacity of 1189.4 mA·h/g at 0.2C.After 300 cycles,S@BNPC still maintains a capacity of 703.2 mA·h/g which corresponds to a fading rate of 0.13%per cycle after the second cycle.This work offers vast opportunities for the large-scale application of high performance carbon-based sulfur hosts.展开更多
The microstructure and texture of C/C composites with a resin-derived carbon, a rough laminar （RL） pyrocarbon and a smooth laminar pyrocarbon, before and after braking tests, were investigated by Raman spectroscopy....The microstructure and texture of C/C composites with a resin-derived carbon, a rough laminar （RL） pyrocarbon and a smooth laminar pyrocarbon, before and after braking tests, were investigated by Raman spectroscopy. The full width at half maximum （FWHM） of the D-band indicates the amount of defects in the in-plane lattice, while the G-to-D band intensity （peak area） ratios （lC/ID） is used to evaluate the degree of graphitization. The results show that the FWHM of D-band of sample with RL pyrocarbon changes greatly from 36 cm-1 to 168 cm 1 after braking tests, which indicates that a large number of lattice defects are produced on its wear surface. However, the graphitization degree of resin-derived carbon sample rises significantly, because the IC/1D increases from 0.427 to 0.928. Braking tests under normal loading conditions, involving high temperature and high pressure, produce a lot of lattice defects on the wear surface, and induce the graphitization of the surface. Sample with RL pyrocarbon having a low hardness is easy to deform, and has the most lattice defects on the wear surface after braking. While raw materials with resin-derived carbon have the lowest graphitization degree which rises greatly during braking.展开更多
A general, simple and economic synthetic method for synthesizing carbon nanofibers was presented. In the method, ethanol was employed as carbon source; metal salts such as nickel nitrate, ferric nitrate and ferric chl...A general, simple and economic synthetic method for synthesizing carbon nanofibers was presented. In the method, ethanol was employed as carbon source; metal salts such as nickel nitrate, ferric nitrate and ferric chloride were used as catalyst precursor respectively; copper plate was employed as the support material. A lot of products were obtained by catalytic combustion deposition of ethanol vapor. Then the as-prepared carbon nanofibers were characterized by field-emission scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, energy dispersion X-ray spectroscopy and selected-area electron diffractometry. By analyzing the results of characterization, the conclusions are as follows: 1) the large catalyst particles tend to form large-diameter CNFs, small catalyst particles are inclinable to form small-diameter CNFs; 2) the morphology of the catalyst can affect the final morphology of the CNFs. Moreover, the possible growth mechanisms were proposed and the degree of graphitization of samples was estimated by Raman spectroscopy characterization.展开更多
基金Projects(2020 JJ 5142,2019 RS 2067)supported by the Science and Technology Planning Project of Hunan Province,ChinaProject(19 C 0581)supported by the Research Foundation of Education Bureau of Hunan Province,China。
文摘Serving as gas diffusion layers(GDLs),the thermal conductivity of carbon paper(CP)plays a significant role in the heat transfer management in fuel cells.In the present study,the effect of graphitization degree of CP on its through plane thermal conductivity and in-plane thermal conductivity is investigated.The relationship between heat treatment temperatures(1800,2000,2200,2400 and 2500℃)and graphitization degree is also investigated by SEM,XRD and Raman measurements.A model for CP under different graphitization degree is suggested considering the thermal conductivity difference of carbon fiber and matrix carbon.The experimental and simulation results are compared.The results show that the graphitization degree has a significant impact on the through-plane thermal conductivity and in plane thermal conductivity.
基金Project(2006CB600903) supported by the National Basic Research Program of China
文摘A novel carbon fiber pretreatment was proposed.Polyacrylonitrile(PAN)-based carbon fibers were first anodized in H3PO4 electrolyte to achieve an active surface,and then coated with Mo-B catalysts by immersed the carbon fibers in a uniformly dispersed Mo-B sol.The as-treated carbon fibers were then graphitized at 2 400 ℃ for 2 h.The structural changes were characterized by X-ray diffractometry(XRD),Raman spectroscopy,scanning electron microscopy(SEM) and high-resolution transmission electronic microscopy(HRTEM).The results show that much better graphitization can be achieved in the presence of Mo-B,with an interlayer spacing(d002) of 0.335 8 nm and a crystalline size(Lc) of 28 nm.
基金Project(2006CB600903) supported by the National Basic Research Program of China
文摘Prussian blue(PB) was used as catalyst to improve the extent of graphitization of polyacrylonitrile(PAN)-based carbon fibers.PB was deposited on carbon fibers by anodic electrodeposition and the thickness of PB coating(PB content) was controlled by adjusting the electrodeposition time.PAN-based carbon fibers with PB coating were heat-treated and the extent of graphitization was measured by X-ray diffractometry and Raman spectroscopy.The results indicate that the extent of graphitization of PAN-based carbon fibers is enhanced in the presence of the coating.When the PB-coated carbon fibers were heat-treated at 1 900 ℃,interlayer spacing(d002) and crystallite size(Lc) reach 0.336 8 and 21.2 nm respectively.Contrarily,the values of d002 and Lc are 0.341 4 and 7.4 nm respectively when the bare carbon fibers were heat-treated at 2 800 ℃.Compared with the bare carbon fibers,PB can make the heat treatment temperature(HTT) drop more than 500 ℃ in order to reach the same extent of graphitization.Furthermore,the research results show that PB content also has a certain influence on the extent of graphitization at the same HTT.
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Lithium-ion batteries(LIBs)are an electrochemical energy storage technology that has been widely used for portable electrical devices,electric vehicles,and grid storage,etc.To satisfy the demand for user convenience especially for electric vehicles,the development of a fast-charging technology for LIBs has become a critical focus.In commercial LIBs,the slow kinetics of Li+intercalation into the graphite anode from the electrolyte solution is known as the main restriction for fast-charging.We summarize the recent advances in obtaining fast-charging graphite-based anodes,mainly involving modifications of the electrolyte solution and graphite anode.Specifically,strategies for increasing the ionic conductivity and regulating the Li+solvation/desolvation state in the electrolyte solution,as well as optimizing the fabrication and the intrinsic activity of graphite-based anodes are discussed in detail.This review considers practical ways to obtain fast Li+intercalation kinetics into a graphite anode from the electrolyte as well as analysing progress in the commercialization of fast-charging LIBs.
文摘As an emerging electrochemical energy storage technology,potassium-ion batteries(PIBs),which are considered a“beyond Li-ion”battery system,have attracted tremendous attention due to their potential for providing a high energy density,and having abundant resource,and a low cost.However,their commercialization is hindered by the lack of practical anode materials.Among various reported anodes,conventional carbon materials,including graphite,soft carbon,and hard carbon,have emerged as promising candidates because of their abundance,low cost,high conductivity,and tunable structures.However,these materials have problems such as a low initial Coulombic efficiency,significant volume expansion,and unsatisfactory cyclability and rate performance.Various strategies to solve these have been explored,including optimizing the interlayer spacing,structural design,surface coating,constructing a multifunctional framework,and forming composites.This review provides a comprehensive overview of the recent progress in conventional carbon anodes,highlighting structural design strategies,mechanisms for improving the electrochemical performance,and underscores the critical role of these materials in promoting the practical application of PIBs.
文摘Iron(Fe)nanoparticles and graphite(Gr)with different masses of bismuth trisulfide(Bi_(2)S_(3))were mixed by high-energy ball milling treatment to fabricate the corresponding composite iron anodes Bi_(2)S_(3)@Fe-Gr.The hydrogen evolution reaction and iron passivation process on these iron electrodes were investigated in alkaline and neutral solutions.The iron electrode Bi_(2)S_(3)-3@Fe-Gr(The additional amount of Bi_(2)S_(3)was 3 mg)revealed the strongest ability to inhibit hydrogen evolution among the iron electrodes of the present investigation,while the Bi_(2)S_(3)-6@Fe-Gr electrode(The additional amount of Bi_(2)S_(3)was 6 mg)delivered significant performance in inhibiting anodic passivation.This is because the high-energy ball milling process leads to the well-dispersion of Bi_(2)S_(3)and the changes in the surface of Fe nanoparticles,thereby slowing down the passivation of the iron electrode surface.
基金National Key Research and Development Program of China(2024YFB3714804)National Natural Science Foundation of China(52171277)+1 种基金Baima Lake Laboratory Joint Funds of the Zhejiang Provincial Natural Science Foundation of China(LBMHZ24E020001)Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering(2022SZ-TD006).
文摘Magnesium potassium phosphate cement(MKPC)coatings exhibit potential for carbon steel protection but face challenges in practical application due to the preparation process and properties.This study develops flake graphite(FG)-modified MKPC coatings via spraying process,investigating the effects of FG size and dosage on phase composition,microstructure,mechanical properties,corrosion protection,and thermal conductivity.Results show that a low FG dosage(5 wt%)synergistically optimizes multifunctional performance.Compared to unmodified MKPC,FG2-1 exhibited exceptional impact resistance,associated with a 57%reduction in corrosion current density(icorr),a 356.3% increase in low-frequency impedance modulus(Z_(0.01 Hz))and a 37% increase in thermal conductivity.However,the coating with a high FG dosage(15 wt%)degraded performance due to defect accumulation and reduced crystallinity of KMgPO_(4)·6H_(2)O.This work advances the rational design of multifunctional inorganic coatings for extreme service environments requiring coupled corrosion protection and thermal management.
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the National Natural Science Foundation of China(12274170 and 52225203)。
文摘Lonsdaleite,also known as hexagonal diamond,is an allotrope of carbon with a hexagonal crystal structure,which was discovered in the nanostructure of the Canyon Diablo meteorite.Theoretical calculations have shown that this structure gives it exceptional physical properties that exceed those of cubic diamond,making it highly promising for groundbreaking applications in superhard cutting tools,wide-bandgap semiconductor devices,and materials for extreme environments.As a result,the controllable synthesis of hexagonal diamond has emerged as a cutting-edge research focus in materials science.This review briefly outlines the progress in this area,with a focus on the mechanisms governing its key synthesis conditions,its intrinsic physical properties,and its potential applications in various fields.
文摘Based on the service characteristics of fuel elements for molten salt reactors,they need to have a high power density,resistance to coolant infiltration,and excellent thermodynamic properties.To solve the problem of the graphite used in the fuel element for these reactors being susceptible to molten salt infiltration,carbon black(CB)was added to increase the density of the graphite,and a fuel element(TRISO(tri-structural isotropic)fuel particles were randomly distributed in the modified graphite matrix)was prepared by cold isostatic pressing process.An out-of-pile performance study shows that the densification and pore structure of the modified graphite matrix were improved,as was the resistance to molten salt infiltration.The median pore size of the modified graphite was reduced from 673 to 433 nm and the threshold pressure for molten salt(FLiBe,66%(molar fraction)LiF and 34%BeF_(2))infiltration was increased from 0.88 to 1.37 MPa.The isotropic CB made the graphite matrix less anisotropic,while its thermal conductivity and compressive strength were reduced due to the difficult graphitization of CB.Fuel elements containing 20%(volume fraction)TRISO particles were prepared.Numerical simulations show that the power and temperature distribution of the fuel were in line with the design requirements.The modified graphite matrix had a higher density,smaller pores,a lower anisotropy and a greater resistance to FLiBe infiltration.
文摘Cu suffers from oxidation and corrosion during application due to its active chemical properties.Graphene⁃modified Cu can significantly improve its stability during application.However,copper is easily sintered at high temperatures,so that graphene cannot be grown inside.We demonstrate two kinds of spacers,graphite and SiO_(2),which are effective in preventing the sintering of copper and are used to assist in the growth of graphene.In the Cu⁃C system,the nucleation of graphene is scarce,and it tends to nucleate and grow on the concave surface of copper first,and then grow epitaxially to the convex surface of copper.Eventually,the obtained graphene is relatively thick.In the Cu⁃SiO_(2) system,due to the oxygen released by SiO_(2) at high temperatures,the surface of copper becomes rough.This leads to an increase in the number of graphene nucleation sites without preferred orientation,and relatively thin graphene is obtained.Two different growth mechanisms have been established for spacerseffects on graphene growth.It provides insights for graphene engineering for further applications.
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.
基金Project(2018YFB0104300)supported by the National Key R&D Program of ChinaProject(51774150)supported by the National Natural Science Foundation of China
文摘Shuttle effect,poor conductivity and large volume expansion are the main factors that hinder the practical application of sulfur cathodes.Currently,rational structure designing of carbon-based sulfur hosts is the most effective strategy to address the above issues.However,the preparation process of carbon-based sulfur hosts is usually complex and costly.Therefore,it is necessary to develop an efficient and cost-effective method to fabricate carbon hosts for high-performance sulfur cathodes.Herein,we reported the fabrication of a bio-derived nitrogen doped porous carbon materials(BNPC)via a molten-salt method for high performance sulfur cathodes.The long-range-ordered honeycomb structure of BNPC is favorable for the trapping of polysulfide(PS)species and accommodates the volumetric variation of sulfur during cycling,while the high graphitization degree of BNPC favors the redox kinetics of sulfur cathodes.Moreover,the nitrogen doping content not only enhances the electrical conductivity of BNPC,but also provides ample anchoring sites for the immobilization of PS,which plays a key role in suppressing the shuttle effect.As a result,the S@BNPC cathode exhibits a high initial specific capacity of 1189.4 mA·h/g at 0.2C.After 300 cycles,S@BNPC still maintains a capacity of 703.2 mA·h/g which corresponds to a fading rate of 0.13%per cycle after the second cycle.This work offers vast opportunities for the large-scale application of high performance carbon-based sulfur hosts.
基金Project(2006CB600906) supported by the National Basic Research Program of China
文摘The microstructure and texture of C/C composites with a resin-derived carbon, a rough laminar （RL） pyrocarbon and a smooth laminar pyrocarbon, before and after braking tests, were investigated by Raman spectroscopy. The full width at half maximum （FWHM） of the D-band indicates the amount of defects in the in-plane lattice, while the G-to-D band intensity （peak area） ratios （lC/ID） is used to evaluate the degree of graphitization. The results show that the FWHM of D-band of sample with RL pyrocarbon changes greatly from 36 cm-1 to 168 cm 1 after braking tests, which indicates that a large number of lattice defects are produced on its wear surface. However, the graphitization degree of resin-derived carbon sample rises significantly, because the IC/1D increases from 0.427 to 0.928. Braking tests under normal loading conditions, involving high temperature and high pressure, produce a lot of lattice defects on the wear surface, and induce the graphitization of the surface. Sample with RL pyrocarbon having a low hardness is easy to deform, and has the most lattice defects on the wear surface after braking. While raw materials with resin-derived carbon have the lowest graphitization degree which rises greatly during braking.
基金Project(66167044) supported by the Academic Human Resources Development in Institutions of Higher Learning under the Jurisdiction of Beijing, ChinaProject(66062021) supported by the Science and Technology Activity for Chinese Homecoming Fellow Abroad, Program of Beijing Key Laboratory for Sensor
文摘A general, simple and economic synthetic method for synthesizing carbon nanofibers was presented. In the method, ethanol was employed as carbon source; metal salts such as nickel nitrate, ferric nitrate and ferric chloride were used as catalyst precursor respectively; copper plate was employed as the support material. A lot of products were obtained by catalytic combustion deposition of ethanol vapor. Then the as-prepared carbon nanofibers were characterized by field-emission scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, energy dispersion X-ray spectroscopy and selected-area electron diffractometry. By analyzing the results of characterization, the conclusions are as follows: 1) the large catalyst particles tend to form large-diameter CNFs, small catalyst particles are inclinable to form small-diameter CNFs; 2) the morphology of the catalyst can affect the final morphology of the CNFs. Moreover, the possible growth mechanisms were proposed and the degree of graphitization of samples was estimated by Raman spectroscopy characterization.
