Transition metal oxides are regarded as promising candidates of anode for next-generation lithium-ion batteries(LIBs)due to their ultrahigh theoretical capacity and low cost,but are restricted by their low conductivit...Transition metal oxides are regarded as promising candidates of anode for next-generation lithium-ion batteries(LIBs)due to their ultrahigh theoretical capacity and low cost,but are restricted by their low conductivity and large volume expansion during Li^(+)intercalation.Herein,we designed and constructed a structurally integrated 3D carbon tube(3D-CT)grid film with Mn_(3)O_(4)nanoparticles(Mn_(3)O_(4)-NPs)and carbon nanotubes(CNTs)filled in the inner cavity of CTs(denoted as Mn_(3)O_(4)-NPs/CNTs@3D-CT)as high-performance free-standing anode for LIBs.The Mn_(3)O_(4)-NPs/CNTs@3D-CT grid with Mn_(3)O_(4)-NPs filled in the inner cavity of 3D-CT not only afford sufficient space to overcome the damage caused by the volume expansion of Mn_(3)O_(4)-NPs during charge and discharge processes,but also achieves highly efficient channels for the fast transport of both electrons and Li+during cycling,thus offering outstanding electrochemical performance(865 mAh g^(-1)at 1 A g^(-1)after 300 cycles)and excellent rate capability(418 mAh g^(-1)at 4 A g^(-1))based on the total mass of electrode.The unique 3D-CT framework structure would open up a new route to the highly stable,high-capacity,and excellent cycle and high-rate performance free-standing electrodes for highperformance Li-ion storage.展开更多
Rapid solidification is regarded as being an effective method to refine the microstructure and reduce or eliminate the segregation of alloying elements.In this study the microstructures of rapid solidified carbon stee...Rapid solidification is regarded as being an effective method to refine the microstructure and reduce or eliminate the segregation of alloying elements.In this study the microstructures of rapid solidified carbon steel droplets (cooled in silicone oil) with different C contents by drop tube processing were observed.The volumes of droplets were set to be 2 mm×2 mm×2 mm (TM) and 5 mm×5 mm×5 mm (FM).For most samples,the microstructures are nearly the same from the surface to the center region.The microstructures of the FM samples with higher C content are much finer than those of the TM samples,which is the opposite of the situation with the lower C content samples.The distribution of C along the diameter of each sample was detected.The segregation of C was observed in TM samples with higher C contents while not in FM samples.This is regarded as relating to recalescence and the diffusion of C atoms during the solidification process.展开更多
Amidst <span><span><span style="font-family:;" "="">the </span></span></span><span><span><span style="font-family:;" "="&...Amidst <span><span><span style="font-family:;" "="">the </span></span></span><span><span><span style="font-family:;" "="">COVID-19 pandemic, environmental problems such as ener<span>gy crisis, global warming, and contamination from pathogenic mi</span>cro-organisms <span>are still prevailed and strongly demanded progress in high</span></span></span></span><span><span><span style="font-family:;" "="">-</span></span></span><span><span><span style="font-family:;" "="">performance</span></span></span><span><span><span style="font-family:;" "=""> energy storing and anti-microbial materials. The nanocomposites are materials <span>that have earned large interest owing to their promising applications for</span> countering global issues related to sustainable energy and</span></span></span><span><span><span style="font-family:;" "=""> a</span></span></span><span><span><span style="font-family:;" "=""> flourishing environ<span>ment. Here, polypyrrole </span></span></span></span><span><span><span style="font-family:;" "="">coated</span></span></span><span><span><span style="font-family:;" "=""> hybrid nanocomposites of multi-walled</span></span></span><span><span><span style="font-family:;" "=""> carbon nanotube and cadmium sulfide quantum dots named MCP were synthe<span>sized using facile and low-cost <i>in-situ</i> oxidative polymerization method.</span> Cha<span>racterization techniques confirmed the synthesis. Electrochemical studies</span> showed that the nanocomposite <span>1-MCP<i> </i></span>showed an impressively higher super capacitance behavior in comparison to f-MWCNT, 7-MCP and 5-MCP. The improved performance of the nanocomposites was attributed mainly to the good conductivity of carbon nanotubes and polypyrrole, high surface area, and stability of the carbon nanotubes and the high electrocatalytic activity of the cadmium sulfide quantum dots. Owing to the synergistic effect of MWCNT, <span>CdS, and PPy the synthesized ternary nanocomposite also inhibited the</span> growth and multiplication of tested bacteria such as <i>S. aureus</i>, and <i>E. coli</i> completely within 24 h. On the whole, the assimilated nanocomposite MCP opens promising aspects for the development of upcoming energy storage devices and as<span style="color:red;"> </span></span></span></span><span><span><span style="font-family:;" "="">an </span></span></span><span><span><span style="font-family:;" "="">antibacterial agent.</span></span></span>展开更多
It has been reported that pitting corrosion in copper tubes occurs due to the effect of a carbon film produced by the influence of undergoing an oil and heat treatment. As a quantitative method for determining the res...It has been reported that pitting corrosion in copper tubes occurs due to the effect of a carbon film produced by the influence of undergoing an oil and heat treatment. As a quantitative method for determining the residual carbon amount, it has been reported that the inner surface of a copper tube can be dissolved with a mixed acid to collect and analyze the adhering carbon;however, this method is dangerous and difficult. Therefore, two methods were examined as a simple quantitative method for obtaining the residual carbon amount using copper tubes with known residual carbon amounts. One method utilizes X-ray photoelectron spectroscopy (XPS), and the other method utilizes the potential difference between the carbon film-adhered surface and carbon film-removed surface. In regard to XPS measurement, a linear correlation was found between the spectral intensity of C and the residual carbon amount;therefore, XPS measurements were considered to be effective as a simple measurement method for the carbon film on the inner surface of a copper tube. In the evaluation method by measuring the corrosion potential, a correlation was observed between the potential difference ΔE and the residual carbon amount of the inner surface of the tube and the outer surface of the polished tube. It is considered possible to estimate the residual carbon amount from the prepared calibration curve. Through these studies, it is suggested that the carbon film was non-uniformly present on the surface of the copper tube. Therefore, the galvanic current was measured, and the effect of a non-uniform carbon film on corrosion behavior was investigated. As a result, in the measurement of galvanic current, the current flowed from the copper tube with a large amount of residual carbon (cathode) to the copper tube with a small amount of residual carbon (anode). In addition, the higher the area ratio of the carbon film was, the larger the galvanic current tended to be.展开更多
A polymer-based carbon nano-tubes (CNTs) composite with high electromagnetic (EM) wave shielding effectiveness (SE) and with high mechanical property is developed for packaging of electronic modulus or devices.The ...A polymer-based carbon nano-tubes (CNTs) composite with high electromagnetic (EM) wave shielding effectiveness (SE) and with high mechanical property is developed for packaging of electronic modulus or devices.The liquid crystal polymers (LCP) and melamine formaldehydes (MF) polymer are used to study the orientation effect of CNTs in various polymeric matrix.The influences of orientation,aspect ratio,and mass fraction of CNTs upon the shielding effectiveness (SE) of CNTs-composites are investigated.The higher the orientation,aspect ratio,and weight percentages of nano-materials are, the higher the SE of the carbon composites.The highest SE for the CNTs/LCP nano composite obtained is more than 62 dB. This results may lead to the developing for CPU IC chip packaging.展开更多
A dispersion system fluid can convect even if the dispersoid is a solid phase.Therefore,heat exchange performance can be improved while maintaining fluidity using a material with high thermal conductivity as the dispe...A dispersion system fluid can convect even if the dispersoid is a solid phase.Therefore,heat exchange performance can be improved while maintaining fluidity using a material with high thermal conductivity as the dispersoid.This study presents the melting performance evaluation results of a latent heat storage material with a carbon nanotube(CNT)dispersion system with high thermal conductivity,which enhances the thermal conductivity of the latent heat storage material and does not limit free convection.Increasing the thermal conductivity and enhancing the melting convection of the heat storage material result in increased latent heat storage speed.In this study,the thermal conductivity of the latent heat storage material was successfully increased by dispersing CNTs in the material.When 0.1%(in mass)of multi-wall CNT(MWCNT)was dispersed in a paraffin-based latent heat storage material,the shear stress increased by 1.5 times at a shear rate of 500 s^(-1),while taking into account the potential effects of convective inhibition.Therefore,a latent heat storage experiment was conducted in a rectangular heat storage tank using the CNT dispersion composition ratio as a parameter.A rectangular vessel with a heated vertical surface was used for the latent heat storage experiment.The melting speed was determined by comparing the amount of latent heat stored in a CNT-dispersed latent heat storage material and a single-phase latent heat storage material sample.The experimental results show that the time required for the latent heat storage material to completely melt in the heat storage tank was the shortest for the single-phase latent heat storage material sample.However,the fastest melting progress was observed for the sample with 0.02%(in mass)MWCNT content in the melting rate range of up to approximately 40%in the tank.The results indicate that this phenomenon is caused by the difference in the melting rates in the upper part of the tank.The generated data are useful for determining the shape and heat transfer surface arrangement of the latent heat storage tank.展开更多
基金supported by the Natural Science Foundation of China(91963202 and 52072372)the Key Research Program of Frontier Sciences(CAS,Grant,QYZDJ-SSW-SLH046)the CAS/SAFEA International Partnership Program for Creative Research Teams,and the Hefei Institutes of Physical Science,Chinese Academy of Sciences Director’s Fund(YZJ ZX202018)
文摘Transition metal oxides are regarded as promising candidates of anode for next-generation lithium-ion batteries(LIBs)due to their ultrahigh theoretical capacity and low cost,but are restricted by their low conductivity and large volume expansion during Li^(+)intercalation.Herein,we designed and constructed a structurally integrated 3D carbon tube(3D-CT)grid film with Mn_(3)O_(4)nanoparticles(Mn_(3)O_(4)-NPs)and carbon nanotubes(CNTs)filled in the inner cavity of CTs(denoted as Mn_(3)O_(4)-NPs/CNTs@3D-CT)as high-performance free-standing anode for LIBs.The Mn_(3)O_(4)-NPs/CNTs@3D-CT grid with Mn_(3)O_(4)-NPs filled in the inner cavity of 3D-CT not only afford sufficient space to overcome the damage caused by the volume expansion of Mn_(3)O_(4)-NPs during charge and discharge processes,but also achieves highly efficient channels for the fast transport of both electrons and Li+during cycling,thus offering outstanding electrochemical performance(865 mAh g^(-1)at 1 A g^(-1)after 300 cycles)and excellent rate capability(418 mAh g^(-1)at 4 A g^(-1))based on the total mass of electrode.The unique 3D-CT framework structure would open up a new route to the highly stable,high-capacity,and excellent cycle and high-rate performance free-standing electrodes for highperformance Li-ion storage.
基金financially supported by the National Natural Science Foundation of China,Project No.51074210
文摘Rapid solidification is regarded as being an effective method to refine the microstructure and reduce or eliminate the segregation of alloying elements.In this study the microstructures of rapid solidified carbon steel droplets (cooled in silicone oil) with different C contents by drop tube processing were observed.The volumes of droplets were set to be 2 mm×2 mm×2 mm (TM) and 5 mm×5 mm×5 mm (FM).For most samples,the microstructures are nearly the same from the surface to the center region.The microstructures of the FM samples with higher C content are much finer than those of the TM samples,which is the opposite of the situation with the lower C content samples.The distribution of C along the diameter of each sample was detected.The segregation of C was observed in TM samples with higher C contents while not in FM samples.This is regarded as relating to recalescence and the diffusion of C atoms during the solidification process.
文摘Amidst <span><span><span style="font-family:;" "="">the </span></span></span><span><span><span style="font-family:;" "="">COVID-19 pandemic, environmental problems such as ener<span>gy crisis, global warming, and contamination from pathogenic mi</span>cro-organisms <span>are still prevailed and strongly demanded progress in high</span></span></span></span><span><span><span style="font-family:;" "="">-</span></span></span><span><span><span style="font-family:;" "="">performance</span></span></span><span><span><span style="font-family:;" "=""> energy storing and anti-microbial materials. The nanocomposites are materials <span>that have earned large interest owing to their promising applications for</span> countering global issues related to sustainable energy and</span></span></span><span><span><span style="font-family:;" "=""> a</span></span></span><span><span><span style="font-family:;" "=""> flourishing environ<span>ment. Here, polypyrrole </span></span></span></span><span><span><span style="font-family:;" "="">coated</span></span></span><span><span><span style="font-family:;" "=""> hybrid nanocomposites of multi-walled</span></span></span><span><span><span style="font-family:;" "=""> carbon nanotube and cadmium sulfide quantum dots named MCP were synthe<span>sized using facile and low-cost <i>in-situ</i> oxidative polymerization method.</span> Cha<span>racterization techniques confirmed the synthesis. Electrochemical studies</span> showed that the nanocomposite <span>1-MCP<i> </i></span>showed an impressively higher super capacitance behavior in comparison to f-MWCNT, 7-MCP and 5-MCP. The improved performance of the nanocomposites was attributed mainly to the good conductivity of carbon nanotubes and polypyrrole, high surface area, and stability of the carbon nanotubes and the high electrocatalytic activity of the cadmium sulfide quantum dots. Owing to the synergistic effect of MWCNT, <span>CdS, and PPy the synthesized ternary nanocomposite also inhibited the</span> growth and multiplication of tested bacteria such as <i>S. aureus</i>, and <i>E. coli</i> completely within 24 h. On the whole, the assimilated nanocomposite MCP opens promising aspects for the development of upcoming energy storage devices and as<span style="color:red;"> </span></span></span></span><span><span><span style="font-family:;" "="">an </span></span></span><span><span><span style="font-family:;" "="">antibacterial agent.</span></span></span>
文摘It has been reported that pitting corrosion in copper tubes occurs due to the effect of a carbon film produced by the influence of undergoing an oil and heat treatment. As a quantitative method for determining the residual carbon amount, it has been reported that the inner surface of a copper tube can be dissolved with a mixed acid to collect and analyze the adhering carbon;however, this method is dangerous and difficult. Therefore, two methods were examined as a simple quantitative method for obtaining the residual carbon amount using copper tubes with known residual carbon amounts. One method utilizes X-ray photoelectron spectroscopy (XPS), and the other method utilizes the potential difference between the carbon film-adhered surface and carbon film-removed surface. In regard to XPS measurement, a linear correlation was found between the spectral intensity of C and the residual carbon amount;therefore, XPS measurements were considered to be effective as a simple measurement method for the carbon film on the inner surface of a copper tube. In the evaluation method by measuring the corrosion potential, a correlation was observed between the potential difference ΔE and the residual carbon amount of the inner surface of the tube and the outer surface of the polished tube. It is considered possible to estimate the residual carbon amount from the prepared calibration curve. Through these studies, it is suggested that the carbon film was non-uniformly present on the surface of the copper tube. Therefore, the galvanic current was measured, and the effect of a non-uniform carbon film on corrosion behavior was investigated. As a result, in the measurement of galvanic current, the current flowed from the copper tube with a large amount of residual carbon (cathode) to the copper tube with a small amount of residual carbon (anode). In addition, the higher the area ratio of the carbon film was, the larger the galvanic current tended to be.
文摘A polymer-based carbon nano-tubes (CNTs) composite with high electromagnetic (EM) wave shielding effectiveness (SE) and with high mechanical property is developed for packaging of electronic modulus or devices.The liquid crystal polymers (LCP) and melamine formaldehydes (MF) polymer are used to study the orientation effect of CNTs in various polymeric matrix.The influences of orientation,aspect ratio,and mass fraction of CNTs upon the shielding effectiveness (SE) of CNTs-composites are investigated.The higher the orientation,aspect ratio,and weight percentages of nano-materials are, the higher the SE of the carbon composites.The highest SE for the CNTs/LCP nano composite obtained is more than 62 dB. This results may lead to the developing for CPU IC chip packaging.
基金supported by JSPS KAKENHI(Grant numbers JP18K03999 and 22K03958)。
文摘A dispersion system fluid can convect even if the dispersoid is a solid phase.Therefore,heat exchange performance can be improved while maintaining fluidity using a material with high thermal conductivity as the dispersoid.This study presents the melting performance evaluation results of a latent heat storage material with a carbon nanotube(CNT)dispersion system with high thermal conductivity,which enhances the thermal conductivity of the latent heat storage material and does not limit free convection.Increasing the thermal conductivity and enhancing the melting convection of the heat storage material result in increased latent heat storage speed.In this study,the thermal conductivity of the latent heat storage material was successfully increased by dispersing CNTs in the material.When 0.1%(in mass)of multi-wall CNT(MWCNT)was dispersed in a paraffin-based latent heat storage material,the shear stress increased by 1.5 times at a shear rate of 500 s^(-1),while taking into account the potential effects of convective inhibition.Therefore,a latent heat storage experiment was conducted in a rectangular heat storage tank using the CNT dispersion composition ratio as a parameter.A rectangular vessel with a heated vertical surface was used for the latent heat storage experiment.The melting speed was determined by comparing the amount of latent heat stored in a CNT-dispersed latent heat storage material and a single-phase latent heat storage material sample.The experimental results show that the time required for the latent heat storage material to completely melt in the heat storage tank was the shortest for the single-phase latent heat storage material sample.However,the fastest melting progress was observed for the sample with 0.02%(in mass)MWCNT content in the melting rate range of up to approximately 40%in the tank.The results indicate that this phenomenon is caused by the difference in the melting rates in the upper part of the tank.The generated data are useful for determining the shape and heat transfer surface arrangement of the latent heat storage tank.