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Effects of doping, Stone Wales and vacancy defects on thermal conductivity of single-wall carbon nanotubes

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Chinese Physics B 2013年第1期22卷 434-440页

作者：冯黛丽冯妍卉陈阳李威张欣欣 School of Mechanical Engineering University of Science and Technology Beijing

The thermal conductivity of carbon nanotubes with certain defects （doping, Stone-Wales, and vacancy） is investigated by using the non-equilibrium molecular dynamics method. The defective carbon nanotubes （CNTs） are compared with perfect tubes. The influences of type and concentration of the defect, length, diameter, and chirality of the tube, and the ambient temperature are taken into consideration. It is demonstrated that defects result in a dramatic reduction of thermal conductivity. Doping and Stone-Wales （SW） defects have greater effect on armchair tubes, while vacancy affects the zigzag ones more. Thermal conductivity of the nanotubes increases, reaches a peak, and then decreases with increasing temperature. The temperature at which the thermal conductivity peak occurs is dependent on the defect type. Different from SW or vacancy tubes, doped tubes are similar to the perfect ones with a sharp peak at the same temperature. Thermal conductivity goes up when the tube length grows or diameter declines. It seems that the length of thermal conductivity convergence for SW tubes is much shorter than perfect or vacancy ones. The SW or vacancy tubes are less sensitive to the diameter change, compared with perfect ones.

关键词： thermal conductivity carbon nanotubes Stone-Wales defects molecular dynamics

Hierarchical nanostructured composite cathode with carbon nanotubes as conductive scaffold for lithium-sulfur batteries

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Journal of Energy Chemistry 2013年第2期22卷 341-346页

作者： Xiaofei Liu Qiang Zhang Jiaqi Huang Shumao Zhang Hongjie Peng Fei Wei Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology Department of Chemical Engineering Tsinghua University

carbon nanotubes （CNTs） are excellent scaffolds for advanced electrode materials, resulting from their intrinsic sp2 carbon hybridization, interconnected electron pathway, large aspect ratio, hierarchical porous structures, and low cost at a large-scale production. How to make full utilization of the mass produced CNTs as building blocks for nanocomposite electrodes is not well understood yet. Herein, a composite cathode containing commercial agglomerated multi-walled CNTs and S for Li-S battery was fabricated by a facile melt-diffusion strategy. The hierarchical CNT@S coaxial nanocables exhibited a discharging capacity of 1020 and 740 mAh .g-1 at 0.5 and 2.0 C, respectively. A rapid capacity decay of 0.7% per cycle at the initial 10 cycles and a slow decay rate of 0.14% per cycle for the later 140 cycles were detected. Such hierarchical agglomerated CNT@ S cathodes show advantages in easy fabrication, environmentally benign, low cost, excellent scalability, and good Li ion storage performance, which are extraordinary composites for high performance Li-S battery.

关键词： carbon nanotubes lithium sulfur battery hierarchical nanocomposite cathode energy storage

Significantly enhanced photocatalytic hydrogen production performance of g-C_(3)N_(4)/CNTs/CdZnS with carbon nanotubes as the electron mediators

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Journal of Materials Science & Technology 2021年第21期80卷 75-83页

作者： Chang Feng Zhuoyuan Chen Jiangping Jing Mengmeng Sun Jing Tian Guiying Lu Li Ma Xiangbo Li Jian Hou Key Laboratory of Marine Environmental Corrosion and Bio-fouling Institute of OceanologyChinese Academy of Sciences7 Nanhai RoadQingdao 266071China State Key Laboratory for Marine Corrosion and Protection Luoyang Ship Material Research Institute(LSMRI)Wenhai RoadQingdao 266237China Center for Ocean Mega-Science Chinese Academy of Sciences7 Nanhai RoadQingdao 266071China University of Chinese Academy of Sciences 19(Jia)Yuquan RoadBeijing 100049China

The electron mediator can effectively improve the performance of the direct Z-scheme heterojunction photocatalysts. However, it is still a great challenge to select cheap and efficient electron mediators and to design them into the Z-scheme photocatalytic system. In the present paper, the g-C_(3)N_(4)/CNTs/CdZnS Z-scheme photocatalyst was prepared using carbon nanotubes(CNTs) as the electron mediators, and its photocatalytic hydrogen production performance was studied. Compared with single-phase g-C_(3)N_(4),CdZnS and biphasic g-C_(3)N_(4)/CdZnS photocatalysts, the photocatalytic hydrogen production performance of the prepared g-C_(3)N_(4)/CNTs/CdZnS has been significantly enhanced. Meanwhile, g-C_(3)N_(4)/CNTs/CdZnS possesses very good photocatalytic hydrogen production stability. The enhanced photocatalytic hydrogen production performance of g-C_(3)N_(4)/CNTs/CdZnS is attributed to the fact that CNTs, as an electron mediator,can accelerate the recombination of the photogenerated holes in the valence band of g-C_(3)N_(4) and the photogenerated electrons in the conduction band of CdZnS, which makes the g-C_(3)N_(4)/CNTs/CdZnS Zscheme photocatalyst be easier to escape the photogenerated electrons, increases the concentration of the photogenerated carriers and prolongs the lifetime of the photogenerated carriers. This work provides a theoretical basis for the further development and design of CNTs as the intermediate electron mediator of the Z-scheme heterojunction photocatalyst.

关键词： Photocatalytic hydrogen production Z-scheme photocatalyst Electron mediator g-C_(3)N_(4)/CNTs/CdZnS carbon nanotubes

sp^(3)-like defect structure of hetero graphene-carbon nanotubes for promoting carrier transfer and stability

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Journal of Energy Chemistry 2021年第6期30卷 189-197,I0005页

作者： Shan-Shan Fan Ling Shen Yuan Dong Ge Tian Si-Ming Wu Gang-Gang Chang Christoph Janiak Ping Wei Jin-Song Wu Xiao-Yu Yang State Key Laboratory of Advanced Technology for Materials Synthesis and Processing and School of Materials Science&EngineeringWuhan University of TechnologyWuhan 430070HubeiChina School of Chemistry Chemical Engineering and Life ScienceWuhan University of TechnologyWuhan 430070HubeiChina Institut für Anorganische Chemie und Strukturchemie Heinrich-Heine-Universität Düsseldorf40204 DüsseldorfGermany NRC(Nanostructure Research Centre) Wuhan University of TechnologyWuhan 430070HubeiChina Department of Engineering and Applied Sciences Harvard University CambridgeMA 02138United States

Three-dimensional(3 D) hybrid of nanocarbons is a very promising way to the high-performance design of electrocatalysis materials.However,sp^(3)-like defect structure,a combination of high strength and conduction of graphene and carbon nanotubes(CNTs) is rarely reported.Herein,3 D neural-like hybrids of graphene(from reduced graphene oxide) and carbon nanotubes(CNTs) have been integrated via sp^(3)-like defect structure by a hydrothermal approach.The sp^(3)-like defect structure endows 3 D nanocarbon hybrids with an enhanced carrier transfer,high structural stability,and electrocatalytic durability.The neural-like structure is shown to demonstrate a cascade effect of charges and significant performances regarding bio-electrocatalysis and lithium-sulfur energy storage.The concept and mechanism of "sp^(3)-like defect structure" are proposed at an atomic/nanoscale to clarify the generation of rational structure as well as the cascade electron transfer.

关键词： Graphene carbon nanotubes sp^(3)-like defect structure Bio-electrocatalysis Lithium-sulfur batteries

Effect of process conditions on the synthesis of carbon nanotubes by catalytic decomposition of methane

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China Particuology 2007年第3期5卷 213-219页

作者： Shuanglin Zhan Yajun Tian Yanbin Cui Hao Wu Yonggang Wang Shufeng Ye Yunfa Chen Institute of Process Engineering Chinese Academy of Sciences Beijing 100080 China Graduate University of Chinese Academy of Sciences Beijing 100049 China China University of Mining and Technology Beijing 100083 China

A new dual-composition catalyst based on Ni-Mo/MgO with high efficiency of producing carbon nanotubes （CNTs） from methane was reported recently. In the present article, with this type of catalyst, the impact of such experimental parameters as reaction temperature, reaction time, concentration of H2, flow rate ratio of CH4 to H2 on yield and graphitization were investigated, leading to the following optimal growth conditions： reaction time 60min, reaction temperature 900℃, CH4：H2 about 100：20mL/min, under which high-yield multi-walled CNTs bundles were synthesized. Raman measurement indicated that the as-synthesized product was well-graphitized, and the purity was estimated over 95% by TG-DSC analysis. In terms of the above results, an explanation of high-efficiency formation of CNTs bundles and the co-catalysis mechanism of Ni-Mo/MgO were suggested. 2007 Chinese Societv of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V.

关键词： carbon nanotubes Catalytic decomposition carbon yield Graphitization degree

Highly electroactive N–Fe hydrothermal carbons and carbon nanotubes for the oxygen reduction reaction

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Journal of Energy Chemistry 2020年第11期29卷 260-270页

作者： R.G.Morais N.Rey-Raap J.L.Figueiredo M.F.R.Pereira Associate Laboratory LSRE-LCM Departamento de Engenharia QuimicaFaculdade de EngenhariaUniversidade do PortoR.Dr.Roberto Frias s/n4200-465PortoPortugal

Glucose-derived carbons were prepared by hydrothermal carbonization of glucose followed by carbonization or activation to obtain carbon materials with different microporosities. These microporous carbons and carbon nanotubes(CNTs) were functionalized with melamine and/or iron(Ⅱ) phthalocyanine(FePc)following three different methodologies:(i) Functionalization with melamine via thermal treatment,(ii)incorporation of the lowest amount of FePc reported in the literature via incipient wetness impregnation followed by thermal treatment and(iii) functionalization with melamine followed by Fe Pc incorporation.The chemical and textural characterization of the prepared materials and their electrochemical assessment allowed to understand the role of microporosity in the incorporation of FePc and its effect on the oxygen reduction reaction(ORR). It was observed that FePc was preferentially incorporated inside the porous structure, especially in samples with more developed microporosity. However, functionalization with melamine modified the textural properties and the surface chemistry, favoring the incorporation of FePc on the surface. Regarding the electrochemical performance, the presence of FePc greatly enhanced the electroactivity of the microporous catalysts. An onset potential of 0.88 V and a four-electron pathway were obtained for glucose-derived carbons, whereas the limiting current densities and kinetic current densities rose by 126% and 222%, respectively, in comparison to the base sample. Notwithstanding, the highest electrochemical activity was observed for the sample prepared with CNTs, due to the synergy between the active metal centers and their highly graphitic carbon structure. The electrochemical parameters of CNTFeP csurpass the commercial Pt/C. The half-wave potential is 40 mV higher, the limiting current density increases by 17%, and a negligible production of by-products(< 1%) was observed.

关键词： Iron(Ⅱ)phthalocyanine Hydrothermal carbons carbon nanotubes Oxygen reduction reaction Electrocatalysis

Interwoven scaffolded porous titanium oxide nanocubes/carbon nanotubes framework for high-performance sodium-ion battery

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Journal of Energy Chemistry 2021年第8期30卷 38-46,I0002页

作者： Wen-Bei Yu Wen-Da Dong Chao-Fan Li Nasiruddin Macadam Jiu-Xiang Yang Guo-Bin Zhang Zhi-Yi Hu Tien-Chun Wu Yu Li Tawfique Hasan Li-Hua Chen Li-Qiang Mai Bao-Lian Su State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China Cambridge Graphene Centre University of Cambridge9 JJ Thomson AvenueCB30FA CambridgeUnited Kingdom Nanostructure Research Centre(NRC) Wuhan University of TechnologyWuhan 430070China Laboratory of Inorganic Materials Chemistry(CMI) University of Namur61 rue de Bruxelles5000 NamurBelgium

Supercapacitor-like Na-ion batteries have attracted much attention due to the high energy density of batteries and power density of capacitors.Titanium dioxide(TiO_(2)),is a promising anode material.Its performance is however seriously hindered by its low electrical conductivity and the sluggish diffusion of sodium ions(Na^(+))in the TiO_(2)matrix.Herein,this work combines porous TiO_(2)nanocubes with carbon nanotubes(CNTs)to enhance the electrical conductivity and accelerate Na^(+)diffusivity for Na-ion batteries(NIBs).In this composite,an interwoven scaffolded TiO_(2)/CNTs framework is formed to provide abundant channels and shorter diffusion pathways for electrons and ions.The in-situ X-ray diffraction and cyclic voltammetry confirm the low strain and superior transport kinetics in Na^(+)intercalation/extraction processes.In addition,the chemically bonded TiO_(2)/CNTs hybrid provides a more feasible channel for Na^(+)insertion/extraction with a much lower energy barrier.Consequently,the TiO_(2)/CNTs composite exhibits excellent electrochemical performance with a capacity of 223.4 m Ah g^(-1)at 1 C and a capacity of 142.8 m Ah g^(-1)at 10 C(3.35 A g^(-1)).The work here reveals that the combination of active materials with CNTs can largely improve the utilization efficiency and enhance their sodium storage.

关键词： Supercapacitor-like Interwoven scaffold Na-ion battery TiO_(2) carbon nanotubes

Fabrication of carbon nanotubes and Rare Earth Pr Reinforced AZ91 Composites by Powder Metallurgy

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Chinese Journal of Mechanical Engineering 2021年第2期34卷 213-222页

作者： Ning Li Hong Yan Qingjie Wu Zeyu Cao School of Mechanical Electrical Engineering Nanchang UniversityNanchang 330031China School of Aviation Manufacturing Engineering Nanchang Hangkong UniversityNanchang 330069China

It can be known from a large number of research results that improving the dispersibility of CNTs can effectively optimize the mechanical properties of the corresponding metal matrix composites.However,the crucial issue of increasing the bonding of CNTs and the matrix is still unsolved.In this paper,a novel method was developed to increase interfacial bonding strength by coating titanium oxide(TiO2)on the surface of CNTs.The rare earth Pr and TiO2@CNTs-reinforced AZ91matrix composites were successfully fabricated by powder metallurgy.Hot press sintering and hot extrusion of the milled powder was performed.After hot extrusion,the influence of TiO2@CNTs on the microstruc-ture and mechanical properties of the composites were investigated.The results showed that the coating process can improve the distribution of CNTs in Mg alloy.The CNTs refined the grains of the matrix,and the CNTs were presented throughout the extrusion direction.When the TiO2@CNTs content was 1.0 wt.%,the yield strength(YS),ultimate ten-sile strength(UTS),and elongation of the alloy attained maximum values.The values were improved by 23.5%,82.1%,and 40.0%,respectively,when compared with the AZ91 alloy.Good interfacial bonding was achieved,which resulted in an effective tensile loading transfer at the interface.CNTs carried the tensile stress and were observed on the tensile fracture.

关键词： carbon nanotubes Titanium oxide AZ91 Coating Rare earth

Uniform and Homogeneous Growth of Copper Nanoparticles on Electrophoretically Deposited carbon nanotubes Electrode for Nonenzymatic Glucose Sensor

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Acta Metallurgica Sinica(English Letters) 2016年第10期29卷 889-894页

作者： Syeda Ammara Shahzadi Shamaila Rehana Sharif Sheeba Ghani Nosheen Zafar Department of Physics University of Engineering and Technology Department of Physics Forman Christian College (A Chartered University)

The multiwalled carbon nanotubes thin-film-based electrode was fabricated by electrophoretic deposition and modified with copper （Cu） nanoparticles to fabricate Cu/CNTs nanocomposite sensor for nonenzymatic glucose detection. The expensive glassy carbon electrode was replaced by fluorine-doped tin oxide glass containing CNTs film to confine the Cu nanoparticles growth by electrodeposition through cyclic voltammetry （CV）. The ultraviolet visible and X-ray diffraction analysis revealed the successful deposition of Cu nanoparticles on the CNTs-modified electrode. The atomic force microscopy images confirrqed the morphology of electrodeposited Cu on CNTs film as uniformly dispersed particles. The electrocatalytic activity of electrode to the glucose oxidation was investigated in alkaline medium by CV and amperometric measurements. The fabricated sensor exhibited a fast response time of less than 5 s and the sensitivity of 314 μA rnM^-1 cm^-2 with linear concentration range （0.02-3.0 mM） having detection limit 10.0 μM. Due to simple preparation of sensor, Cu/CNTs nanocomposite electrodes are a suitable candidate for reliable determination of glucose with good stability.

关键词： Electrophoretic deposition （EPD） Fluorine-doped tin oxide （FTO） substrate carbon nanotubes Copper nanoparticles Nonenzymatic electrocatalysis Glucose sensor