K-ion battery (KIB) is a new-type energy storage device that possesses potential advantages of low-cost and abundant resource of potassium.To develop advanced electrode materials for accommodating the large size and h...K-ion battery (KIB) is a new-type energy storage device that possesses potential advantages of low-cost and abundant resource of potassium.To develop advanced electrode materials for accommodating the large size and high activity of potassium ion is of great interests.Herein,a segment-like antimony (Sb) nanorod encapsulated in hollow carbon tube electrode material (Sb@HCT) was prepared.Beneficial from the virtue of abundant nitrogen doping in carbon tube,one-dimensional and hollow structure advantages,Sb@HCT exhibits excellent potassium storage properties:in the case of potassium bis(fluorosulfonyl)imide (KFSI) electrolyte,Sb@HCT displays a reversible capacity of up to 453.4 mAh·g^-1 at a current density of 0.5 A·g^-1 and good rate performance (a capacity of 211.5 mAh·g^-1 could be achieved at an ultrahigh rate of 5 A·g^-1).Additionally,Sb@HCT demonstrates excellent long-cycle stability at a current density of 2 A·g^-1 over 120 cycles.Meanwhile,electrolyte optimization is an effective strategy for greatly improving electrochemical performance.Through ex-situ characterizations,we disclosed the potassiation of Sb anode is quite reversible and undergoes multistep processes,combining solid solution reaction and two-phase reaction.展开更多
A356 aluminum alloys reinforced with carbon nano-tubes (CNTs) were produced by stir casting and compocasting routes and their microstructural characteristics and hardness were examined.In order to alleviate the proble...A356 aluminum alloys reinforced with carbon nano-tubes (CNTs) were produced by stir casting and compocasting routes and their microstructural characteristics and hardness were examined.In order to alleviate the problems associated with poor wettability, agglomeration and gravity segregation of CNTs in the melt, CNTs were introduced into the melts by injection of CNT deposited aluminum particles instead of raw CNTs.Aluminum particles with mean diameters of less than 100 μm were first deposited by CNTs using Ni-P electroless plating technique and then injected into the melt agitated by a mechanical stirrer.The slurry was subsequently cast at temperatures corresponding to full liquid as well as 0.15 and 0.30 solid fractions.The results show that addition of CNTs to A356 matrix can significantly refine both full liquid and semi-solid cast microstructures.Hardness of the samples is also significantly increased by addition of CNTs and A356-CNT composite cast at 0.3 solid fraction produces the highest hardness.展开更多
对CO_2在内径1.5 mm水平微细管内流动沸腾换热摩擦压降特性进行了实验研究。实验工况:热通量(7.5~30 k W·m-2)、质量流率(300~600 kg·m-2·s-1)、饱和温度(-40~0℃)。实验结果表明:热通量的增加对摩擦压降影响很小,几乎为...对CO_2在内径1.5 mm水平微细管内流动沸腾换热摩擦压降特性进行了实验研究。实验工况:热通量(7.5~30 k W·m-2)、质量流率(300~600 kg·m-2·s-1)、饱和温度(-40~0℃)。实验结果表明:热通量的增加对摩擦压降影响很小,几乎为零;质量流率是影响摩擦压降的最主要因素;随着饱和温度的升高摩擦压降减小;干度对摩擦压降影响主要由管内流型变化导致。将实测摩擦压降变化趋势绘制于CO_2流态图中,比较发现理论预测摩擦压降最大值落在环状流末端区域。实验过程中对各个工况管内流态进行可视化研究,理论分析所采用的流态形式与实际CO_2在微细通道内所具有的流态类型基本一致。展开更多
Electric double-layer capacitors(EDLCs)with fast frequency response are regarded as small-scale alternatives to the commercial bulky aluminum electrolytic capacitors.Creating carbon-based nanoarray electrodes with pre...Electric double-layer capacitors(EDLCs)with fast frequency response are regarded as small-scale alternatives to the commercial bulky aluminum electrolytic capacitors.Creating carbon-based nanoarray electrodes with precise alignment and smooth ion channels is crucial for enhancing EDLCs’performance.However,controlling the density of macropore-dominated nanoarray electrodes poses challenges in boosting the capacitance of line-filtering EDLCs.Herein,a simple technique to finely adjust the vertical-pore diameter and inter-spacing in three-dimensional nanoporous anodic aluminum oxide(3D-AAO)template is achieved,and 3D compactly arranged carbon tube(3D-CACT)nanoarrays are created as electrodes for symmetrical EDLCs using nanoporous 3D-AAO template-assisted chemical vapor deposition of carbon.The 3D-CACT electrodes demonstrate a high surface area of 253.0 m^(2) g^(−1),a D/G band intensity ratio of 0.94,and a C/O atomic ratio of 8.As a result,the high-density 3D-CT nanoarray-based sandwich-type EDLCs demonstrate a record high specific areal capacitance of 3.23 mF cm^(-2) at 120 Hz and exceptional fast frequency response due to the vertically aligned and highly ordered nanoarray of closely packed CT units.The 3D-CT nanoarray electrode-based EDLCs could serve as line filters in integrated circuits,aiding power system miniaturization.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 arr展开更多
Exploring superior electrocatalyst for hydrogen evolution reaction(HER)is an urgent need for hydrogen production based on water splitting.The redistribution of electrons and the increase of active sites through multi-...Exploring superior electrocatalyst for hydrogen evolution reaction(HER)is an urgent need for hydrogen production based on water splitting.The redistribution of electrons and the increase of active sites through multi-interface designing of electrocatalyst are powerful strategies to improve the catalytic efficiency.Herein,a three-phase interface structure of N,P co-doped carbon tube embedded with MoO_(2)/Mo_(2)C(MoO_(2)/Mo_(2)C-CT)was fabricated via a cooperative polymerizing-embedding and pyrolysis strategy.Work function and X-ray photoelectron spectroscopy(XPS)verified that the interfacial charge was quantificationally modulated,achieving an intrinsically enhanced charge transfer by an induced built-in electric field.Theoretical study of density functional theory(DFT)illustrated that triple-interface structure showed a lower energy for H*+H2O*than that of single-interface counterparts.The triple-interface MoO_(2)/Mo_(2)C-CT delivered a lower overpotential of 129 mV at 10 mA·cm^(−2)than that of either single-interface MoO_(2)-CT or Mo_(2)C-CT catalyst.This work may put forward an attractive approach for modulating electronic structure and provide insights into the understanding of triple-interface structure towards HER.展开更多
基金the National Natural Science Foundation of China (No.51832004)the National Natural Science Fund for Distinguished Young Scholars (No.51425204)+2 种基金the National Key R&D Program of China (No.2016YFA0202603)the Programme of Introducing Talents of Discipline to Universities (No.B17034)the Yellow Crane Talent (Science & Technology) Program of Wuhan City.
文摘K-ion battery (KIB) is a new-type energy storage device that possesses potential advantages of low-cost and abundant resource of potassium.To develop advanced electrode materials for accommodating the large size and high activity of potassium ion is of great interests.Herein,a segment-like antimony (Sb) nanorod encapsulated in hollow carbon tube electrode material (Sb@HCT) was prepared.Beneficial from the virtue of abundant nitrogen doping in carbon tube,one-dimensional and hollow structure advantages,Sb@HCT exhibits excellent potassium storage properties:in the case of potassium bis(fluorosulfonyl)imide (KFSI) electrolyte,Sb@HCT displays a reversible capacity of up to 453.4 mAh·g^-1 at a current density of 0.5 A·g^-1 and good rate performance (a capacity of 211.5 mAh·g^-1 could be achieved at an ultrahigh rate of 5 A·g^-1).Additionally,Sb@HCT demonstrates excellent long-cycle stability at a current density of 2 A·g^-1 over 120 cycles.Meanwhile,electrolyte optimization is an effective strategy for greatly improving electrochemical performance.Through ex-situ characterizations,we disclosed the potassiation of Sb anode is quite reversible and undergoes multistep processes,combining solid solution reaction and two-phase reaction.
文摘A356 aluminum alloys reinforced with carbon nano-tubes (CNTs) were produced by stir casting and compocasting routes and their microstructural characteristics and hardness were examined.In order to alleviate the problems associated with poor wettability, agglomeration and gravity segregation of CNTs in the melt, CNTs were introduced into the melts by injection of CNT deposited aluminum particles instead of raw CNTs.Aluminum particles with mean diameters of less than 100 μm were first deposited by CNTs using Ni-P electroless plating technique and then injected into the melt agitated by a mechanical stirrer.The slurry was subsequently cast at temperatures corresponding to full liquid as well as 0.15 and 0.30 solid fractions.The results show that addition of CNTs to A356 matrix can significantly refine both full liquid and semi-solid cast microstructures.Hardness of the samples is also significantly increased by addition of CNTs and A356-CNT composite cast at 0.3 solid fraction produces the highest hardness.
文摘对CO_2在内径1.5 mm水平微细管内流动沸腾换热摩擦压降特性进行了实验研究。实验工况:热通量(7.5~30 k W·m-2)、质量流率(300~600 kg·m-2·s-1)、饱和温度(-40~0℃)。实验结果表明:热通量的增加对摩擦压降影响很小,几乎为零;质量流率是影响摩擦压降的最主要因素;随着饱和温度的升高摩擦压降减小;干度对摩擦压降影响主要由管内流型变化导致。将实测摩擦压降变化趋势绘制于CO_2流态图中,比较发现理论预测摩擦压降最大值落在环状流末端区域。实验过程中对各个工况管内流态进行可视化研究,理论分析所采用的流态形式与实际CO_2在微细通道内所具有的流态类型基本一致。
基金supported by the National Natural Science Foundation of China(91963202,52072372,52372241,52232007,12325203)HFIPS Director’s Fund(BJPY2023A07,YZJJ-GGZX-2022-01).
文摘Electric double-layer capacitors(EDLCs)with fast frequency response are regarded as small-scale alternatives to the commercial bulky aluminum electrolytic capacitors.Creating carbon-based nanoarray electrodes with precise alignment and smooth ion channels is crucial for enhancing EDLCs’performance.However,controlling the density of macropore-dominated nanoarray electrodes poses challenges in boosting the capacitance of line-filtering EDLCs.Herein,a simple technique to finely adjust the vertical-pore diameter and inter-spacing in three-dimensional nanoporous anodic aluminum oxide(3D-AAO)template is achieved,and 3D compactly arranged carbon tube(3D-CACT)nanoarrays are created as electrodes for symmetrical EDLCs using nanoporous 3D-AAO template-assisted chemical vapor deposition of carbon.The 3D-CACT electrodes demonstrate a high surface area of 253.0 m^(2) g^(−1),a D/G band intensity ratio of 0.94,and a C/O atomic ratio of 8.As a result,the high-density 3D-CT nanoarray-based sandwich-type EDLCs demonstrate a record high specific areal capacitance of 3.23 mF cm^(-2) at 120 Hz and exceptional fast frequency response due to the vertically aligned and highly ordered nanoarray of closely packed CT units.The 3D-CT nanoarray electrode-based EDLCs could serve as line filters in integrated circuits,aiding power system miniaturization.
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 arr
基金support by the Fundamental Research Funds for the Central Universities(No.22120220058)athe Instrumental Analysis Fund of Tongji University(No.2022GX072).
文摘Exploring superior electrocatalyst for hydrogen evolution reaction(HER)is an urgent need for hydrogen production based on water splitting.The redistribution of electrons and the increase of active sites through multi-interface designing of electrocatalyst are powerful strategies to improve the catalytic efficiency.Herein,a three-phase interface structure of N,P co-doped carbon tube embedded with MoO_(2)/Mo_(2)C(MoO_(2)/Mo_(2)C-CT)was fabricated via a cooperative polymerizing-embedding and pyrolysis strategy.Work function and X-ray photoelectron spectroscopy(XPS)verified that the interfacial charge was quantificationally modulated,achieving an intrinsically enhanced charge transfer by an induced built-in electric field.Theoretical study of density functional theory(DFT)illustrated that triple-interface structure showed a lower energy for H*+H2O*than that of single-interface counterparts.The triple-interface MoO_(2)/Mo_(2)C-CT delivered a lower overpotential of 129 mV at 10 mA·cm^(−2)than that of either single-interface MoO_(2)-CT or Mo_(2)C-CT catalyst.This work may put forward an attractive approach for modulating electronic structure and provide insights into the understanding of triple-interface structure towards HER.
