Structural properties of water around uncharged and charged carbon nanotubes

Mozaffar Ali Mehrabian,Amir Reza Ansari Dezfoli,Hassan Hashemipour Rafsanjani 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.3

Studying the structural properties of water molecules around the carbon nanotubes is very important in a wide variety of carbon nanotubes applications. We studied the number of hydrogen bonds, oxygen and hydrogen density distributions, and water orientation around carbon nanotubes. The water density distribution for all carbon nanotubes was observed to have the same feature. In water-carbon nanotubes interface, a high-density region of water molecules exists around carbon nanotubes. The results reveal that the water orientation around carbon nanotubes is roughly dependent on carbon nanotubes surface charge. The water molecules in close distances to carbon nanotubes were found to make an HOH plane nearly perpendicular to the water-carbon nanotubes interface for carbon nanotubes with negative surface charge. For uncharged carbon nanotubes and carbon nanotubes with positive surface charge, the HOH plane was in tangential orientation with water-carbon nanotubes interface. There was also a significant reduction in hydrogen bond of water region around carbon nanotubes as compared with hydrogen bond in bulk water. This reduction was very obvious for carbon nanotubes with positive surface charge. In addition, the calculation of dynamic properties of water molecules in water-CNT interface revealed that there is a direct relation between the number of Hbonds and selfdiffusion coefficient of water molecules.

Fabrication of carbon nanotube reinforced alumina matrix nanocomposite by sol–gel process

Mo, Chan B.,Cha, Seung I.,Kim, Kyung T.,Lee, Kyung H.,Hong, Soon H. Elsevier 2005 Materials science & engineering. properties, micro Vol.395 No.1

<P><B>Abstract</B></P><P>Carbon nanotube reinforced alumina matrix nanocomposite was fabricated by sol–gel process and followed by spark plasma sintering process. Homogeneous distribution of carbon nanotubes within alumina matrix can be obtained by mixing the carbon nanotubes with alumina sol and followed by condensation into gel. The mixed gel, consisting of alumina and carbon nanotubes, was dried and calcinated into carbon nanotube/alumina composite powders. The composite powders were spark plasma sintered into carbon nanotube reinforced alumina matrix nanocomposite. The hardness of carbon nanotube reinforced alumina matrix nanocomposite was enhanced due to an enhanced load sharing of homogeneously distributed carbon nanotubes. At the same time, the fracture toughness of carbon nanotube reinforced alumina matrix nanocomposite was enhanced due to a bridging effect of carbon nanotubes during crack propagation.</P>

Tuning sodium nucleation and stripping by the mixed surface of carbon nanotube-sodium composite electrodes for improved reversibility

Kim, Yun-Jung,Lee, Jinhong,Yuk, Seongmin,Noh, Hyungjun,Chu, Hyunwon,Kwack, Hobeom,Kim, Seokwoo,Ryou, Myung-Hyun,Kim, Hee-Tak Elsevier 2019 Journal of Power Sources Vol.438 No.-

<P><B>Abstract</B></P> <P>Metallic sodium is regarded as a promising anode material for sodium rechargeable batteries. However, sodium dendrite growth and exhaustive electrolyte decomposition cause the poor reversibility of the sodium metal electrode. Here, we present that, by forming a mixed surface of carbon and sodium metal, the sodium electrodeposition mode and stripping mechanism can be tuned. In order to systematically investigate sodium plating/stripping behavior on a mixed surface of carbon and sodium, we fabricate a carbon nanotube-sodium composite electrode with a simple rolling and folding method. As the carbon nanotube content is increased, the overpotentials for sodium nucleation and pit-formation are remarkably reduced. Postmortem and chronoamperometry analysis elucidate that sodium and sodiated carbon nanotube have a different sodium nucleation mode, and sodium nucleation is preferred on the sodiated carbon nanotube surface with lower nucleation energy, inducing a more uniform sodium deposition. Furthermore, the embedded carbon nanotube appears to help sodium stripping by providing a channel for a more facile sodium ion transport. As a result, the carbon nanotube-sodium composite electrode exhibites a 5 times higher cycling stability. The tuning of the nucleation and stripping behaviors by forming a mixed surface can be a viable approach for enhancing the reversibility of metal electrode.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Carbon nanotube(CNT) is introduced to Na metal anode by a rolling and folding method. </LI> <LI> Electrically conductive CNT network induces more uniform and dense Na nucleation. </LI> <LI> Embedded CNT helps Na stripping by providing a facile channels for Na ion transport. </LI> <LI> CNT-Na composite electrode exhibits a 5-times improved cycling stability. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

다중벽 탄소나노튜브가 시멘트 페이스트의 유변학적 물성 및 압축강도에 미치는 영향

김지현(Ji-Hyun Kim),김원우(Won-Woo Kim),문재흠(Jae-Heum Moon),정철우(Chul-Woo Chung) 한국건설순환자원학회 2020 한국건설순환자원학회 논문집 Vol.8 No.4

탄소나노튜브는 뛰어난 역학적 성능 및 기능성으로 다양한 분야에서 활용되고 있는 나노소재이다. 탄소나노튜브를 건설재료 분야에 활용하는 연구는 현재의 화두 중 하나로, 예전에 비해 점차 많은 연구가 진행되고 있으나, 탄소나노튜브의 혼입률이 시멘트 페이스트의 압축강도 및 유변학적 물성에 미치는 영향을 검증한 문헌은 상대적으로 부족한 것으로 나타났다. 본 연구에서는 Polyvinyl Pyrrolidone을 사용하여 수용액 분산된 다중벽 탄소나노튜브를 이용하여 시멘트 페이스트를 제조하고, 이의 유변학적 물성 및 압축강도 특성을 확인하고자 하였다. 본 연구의 결과에 따르면, 탄소나노튜브의 혼입률이 증가할수록 소성점도 및 소성항복응력의 증가가 발생하였으며, 물시멘트비가 낮은 경우에 이러한 경향이 더욱 뚜렷하게 드러나는 것이 확인되었다. 탄소나노튜브 혼입 시멘트 페이스트의 압축강도는 물시멘트비가 0.30인 경우 탄소나노튜브 혼입률 0.1wt%에서, 물시멘트비가 0.40인 경우에는 혼입률 0.2wt%에서 최대가 되는 것으로 나타났다. Carbon nanotube has excellent mechanical strength and functionality, so it has been utilized in various applications. In recent years, utilization of carbon nanotube in construction material has started to get interests from researchers in the area of construction materials. However, there is limited amount of work with respect to the rheological properties of cement paste using carbon nanotube. In this work, solution made of multi-walled carbon nanotube with dispersing agent of polyvinyl pyrrolidone was used to prepare cement paste specimens, and rheological properties and 28 day compressive strengths of cement paste using multi-walled carbon nanotube were measured. According to the experimental results, as the amounnt of multi-walled carbon nanotube increased, plastic viscosity and yield stress of cement paste specimens also increased. It was also found that such effect was higher with lower w/c cement paste specimens. With respect to the compressive strength, it was maximized at carbon nanotube content of 0.1wt.% for w/c 0.30 cement paste, whereas the maximum strength of w/c 0.40 cement paste was observed with carbon nanotube content of 0.2wt%.

Singlewall carbon nanotubes covered with polystyrene nanoparticles by in-situ miniemulsion polymerization

Ham, Hyeong Taek,Choi, Yeong Suk,Chee, Mu Guen,Chung, In Jae Wiley Subscription Services, Inc., A Wiley Company 2006 Journal of polymer science Part A, Polymer chemist Vol.44 No.1

<P>This work is to make carbon nanotubes dispersible in both water and organic solvents without oxidation and cutting nanotube threads. Polystyrene-singlewall carbon nanotube (PS-SWNT) composites were prepared with three different methods: miniemulsion polymerization, conventional emulsion polymerization, and mixing SWNT with PS latex. The two factors, crosslinking and surface coverage of PS are important factors for the mechanical and electrical properties, including dispersion states of SWNT in various solvents. The PS-SWNT composite prepared via a conventional emulsion polymerization showed SWNT bundles entirely covered with PS, whereas the PS-SWNT composite prepared via a miniemulsion polymerization showed SWNT partially covered with crosslinked PS nanoparticles. The method of mixing SWNTs with PS latex did not show the well dispersed state of carbon nanotubes because PS was not crosslinked and was dissolved in a solvent, and nanotubes separated from PS precipitated. So the PS nanoparticle-SWNT composite had lower electrical resistance, and higher mechanical strength than the other composites made by the latter two methods. As the amount of SWNT increases, the bare surface area of SWNT increases and the electrical conductivity increases in the composite made by the miniemulsion polymerization. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 573–584, 2006</P> <B>Graphic Abstract</B> <P>Singlewall carbon nanotubes covered with polystyrene nanoparticles were prepared via in-situ miniemulsion polymerization. Polystyrene nanoparticles were attached on the surface of singlewall carbon nanotubes. The nanoparticles partially covered the sidewall of carbon nanotubes. The bare surface of singlewall carbon nanotubes and polystyrene nanoparticle attached singlewall carbon nanotubes were coexisted. Polystyrene-singlewall carbon nanotube composites were prepared with three different methods: miniemulsion polymerization, conventional emulsion polymerization, and mixing SWNT with PS latex. Their structural difference and properties were examined. <img src='wiley_img/0887624X-2006-44-1-POLA21185-gra001.gif' alt='wiley_img/0887624X-2006-44-1-POLA21185-gra001'> </P>

Practical Preparation of Carbon Black/Carbon Nitride Compounds and Their Photocatalytic Performance

Shaozheng Hu,Haoying Wang,Fei Wang,Jin Bai,Lei Zhang,Xiaoxue Kang,GuangWu 대한화학회 2015 Bulletin of the Korean Chemical Society Vol.36 No.10

Here we report a carbon-black-modified g-C3N4 nanocomposite prepared by a convenient method and its photocatalytic performance, which was compared with other carbon-material-, carbon nanotube (CNT)-, C60-, and graphene (GR)-modified g-C3N4 nanocomposites. X-ray diffraction, N2 adsorption, UV–vis spectroscopy, X-ray photoelectron spectroscopy, electrochemical impedance spectroscopy, and photoluminescence were used to characterize the prepared composite material. The results reveal that incorporating g-C3N4 with carbon materials decreases the bandgap and the electron–hole recombination rate of the prepared catalysts. No significant difference was observed in the structural and optical properties among these four series of carbon-material-modified g-C3N4 nanocomposites. Carbon-based materials cannot act as visible-light sensitizers but they can facilitate the separation and transport of photogenerated carriers. These composites obey a tentative reaction mechanism similar to rhodamine B (RhB) photocatalytic degradation. Carbon-black-modified g-C3N4 exhibits comparable activity and stability as those of GR-modified g-C3N4 , which is better than the modification by C60 and CNTs. Compared to CNTs, GR, and C60 , carbon black is a cheap and effective carbon source with excellent photocatalytic performance for the preparation of carbon material/g-C3N4 nanocomposites.

Iron-Oxide-Supported Nanocarbon in Lithium-Ion Batteries, Medical, Catalytic, and Environmental Applications

Tuč,ek, Jiř,í,Kemp, Kingsley Christian,Kim, Kwang Soo,Zboř,il, Radek American Chemical Society 2014 ACS NANO Vol.8 No.8

<P>Owing to the three different orbital hybridizations carbon can adopt, the existence of various carbon nanoallotropes differing also in dimensionality has been already affirmed with other structures predicted and expected to emerge in the future. Despite numerous unique features and applications of 2D graphene, 1D carbon nanotubes, or 0D fullerenes, nanodiamonds, and carbon quantum dots, which have been already heavily explored, any of the existing carbon allotropes do not offer competitive magnetic properties. For challenging applications, carbon nanoallotropes are functionalized with magnetic species, especially of iron oxide nature, due to their interesting magnetic properties (superparamagnetism and strong magnetic response under external magnetic fields), easy availability, biocompatibility, and low cost. In addition, combination of iron oxides (magnetite, maghemite, hematite) and carbon nanostructures brings enhanced electrochemical performance and (photo)catalytic capability due to synergetic and cooperative effects. This work aims at reviewing these advanced applications of iron-oxide-supported nanocarbon composites where iron oxides play a diverse role. Various architectures of carbon/iron oxide nanocomposites, their synthetic procedures, physicochemical properties, and applications are discussed in details. A special attention is devoted to hybrids of carbon nanotubes and rare forms (mesoporous carbon, nanofoam) with magnetic iron oxide carriers for advanced environmental technologies. The review also covers the huge application potential of graphene/iron oxide nanocomposites in the field of energy storage, biomedicine, and remediation of environment. Among various discussed medical applications, magnetic composites of zero-dimensional fullerenes and carbon dots are emphasized as promising candidates for complex theranostics and dual magneto-fluorescence imaging.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2014/ancac3.2014.8.issue-8/nn501836x/production/images/medium/nn-2014-01836x_0047.gif'></P>

Carbon-Coated Magnetite Embedded on Carbon Nanotubes for Rechargeable Lithium and Sodium Batteries

Park, Dae-Yeop,Myung, Seung-Taek American Chemical Society 2014 ACS APPLIED MATERIALS & INTERFACES Vol.6 No.14

<P>Fe<SUB>3</SUB>O<SUB>4</SUB>, carbon-coated Fe<SUB>3</SUB>O<SUB>4</SUB>, and carbon-coated Fe<SUB>3</SUB>O<SUB>4</SUB> embedded on carbon nanotubes are synthesized via hydrothermal reaction. Scanning electron microscopic analysis reveals that particle size of the as-synthesized Fe<SUB>3</SUB>O<SUB>4</SUB> ranges 100–250 nm, whereas carbon-coated Fe<SUB>3</SUB>O<SUB>4</SUB> ranges 10–15 nm in diameter and is surrounded by a thin carbon layer derived from sucrose. The surface modification by carbon is effective in prohibiting crystal growth during hydrothermal reaction. The carbon-coated Fe<SUB>3</SUB>O<SUB>4</SUB> is loaded on conductive carbon nanotubes during a hydrothermal reaction where the carbon nanotubes are added prior to the reaction. Li and Na cell tests indicate that the carbon-coated Fe<SUB>3</SUB>O<SUB>4</SUB> embedded on carbon nanotubes exhibits excellent capacity retention and a good rate capability compared to those of Fe<SUB>3</SUB>O<SUB>4</SUB> and carbon-coated Fe<SUB>3</SUB>O<SUB>4</SUB>. For both cases, the presence of conductive carbon nanotubes provides a conduction path of electrons and is thereby responsible for good capacity retention. These results demonstrate the feasibility of dual alkali ions (Li<SUP>+</SUP> and Na<SUP>+</SUP>) storage in inexpensive magnetite.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2014/aamick.2014.6.issue-14/am502424j/production/images/medium/am-2014-02424j_0011.gif'></P>

Characterization of hybrid carbon nanotubes/carbon fibers-reinforced composites: effect of carbon nanotube content on thermal and mechanical properties of the composites

함은광,최웅기,김영근,서민강 한국공업화학회 2014 한국공업화학회 연구논문 초록집 Vol.2014 No.1

Since the hybrid composites have mechanical properties better than metal composites, these have been required in aerospace, sporting goods, daily necessities, and etc. In this work, the effect of carbon nanotube content on thermal and mechanical properties of carbon nanotubes/carbon fibers-reinforced composites was investigated. The polymer resins used were epoxy and vinyl ester. Carbon nanotube content was added up to 1.0wt% in carbon fibers-reinforced composites. Thermal and mechanical properties of the composites were studied by thermal conductivity, tensile strength, interlaminar shear strength, and impact strength measurements. Morphologies of Carbon fibers-reinforced composites were measured by SEM and TEM.

Characterization of hybrid carbon nanotubes/carbon fibers-reinforced composites: effect of carbon nanotube content on electromagnetic interference properties of the composites

함은광,최웅기,김영근,서민강 한국공업화학회 2014 한국공업화학회 연구논문 초록집 Vol.2014 No.1

In recent years, the metal has used commonly for electromagnetic wave shielding, but there has disadvantages such as expensive and heavy. Carbon nanotubes/carbon fibers-reinforced composites have attracted attention due to benefit such as stiffness, flexibility, and low weight. In this work, the effect of electroless plating and anodizing treated carbon nanotube on electromagnetic interference (EMI) properties of carbon nanotubes/carbon fibers-reinforced composites was studied. The tensile and flexural properties of the composites were also investigated. Carbon nanotube content was varied with 0.3wt%, 0.7wt%, and 1.0wt% in carbon fibers-reinforced composites.