Carbon-Nanotube Growth over Iron Nanoparticles Formed on CaCO3 Support by Using Hydrogen Reduction

Nguyen Duc Dung,Nguyen Van Chuc,Ngo Thi Thanh Tam,Nguyen Hong Quang,Phan Hong Khoi,Phan Ngoc Minh 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.5

Carbon nanotubes (CNTs) were grown by chemical vapor deposition on a mixture of iron salt and CaCO3. Salt mixtures of Fe(NO₃)₃9H₂O/CaCO₃ and FeCl₃6H₂O/CaCO₃ with various Fe weight contents were used as catalysts for growing the CNTs. A scanning electron microscope study revealed that the CNTs were densely grown on the Fe(NO₃)₃9H₂O/CaCO₃ catalyst containing 5 wt.% Fe. The effect of growth temperature on the segregation of Fe nanoparticles formed by hydrogen reduction is discussed. The result shows that 800 ℃ is the optimal temperature for the formation of Fe nanoparticles over which CNTs grow with the highest yield of 78.61 %. A raman spectroscope and a scanning transmission electron microscope were utilized to characterize the multiwall structure of the CNTs. The 92.16 % purity of the CNTs was determined by using thermal gravimetric analysis. Carbon nanotubes (CNTs) were grown by chemical vapor deposition on a mixture of iron salt and CaCO3. Salt mixtures of Fe(NO₃)₃9H₂O/CaCO₃ and FeCl₃6H₂O/CaCO₃ with various Fe weight contents were used as catalysts for growing the CNTs. A scanning electron microscope study revealed that the CNTs were densely grown on the Fe(NO₃)₃9H₂O/CaCO₃ catalyst containing 5 wt.% Fe. The effect of growth temperature on the segregation of Fe nanoparticles formed by hydrogen reduction is discussed. The result shows that 800 ℃ is the optimal temperature for the formation of Fe nanoparticles over which CNTs grow with the highest yield of 78.61 %. A raman spectroscope and a scanning transmission electron microscope were utilized to characterize the multiwall structure of the CNTs. The 92.16 % purity of the CNTs was determined by using thermal gravimetric analysis.

초고속 유성형 매체 분쇄기를 이용한 건식분쇄공정에서 Al/CNTs 복합재 제조를 위한 알루미늄분말의 분쇄거동

최희규,이재현,김성수,최경필,배대형,이승백,이웅,Choi, Heekyu,Lee, Jehyun,Kim, Seongsoo,Choi, Gyungpil,Bae, Daehyung,Lee, Sungbak,Lee, Woong 한국재료학회 2013 한국재료학회지 Vol.23 No.2

The study of grinding behavior characteristics on aluminum powders and carbon nano tubes (CNTs) has recently gained scientific interest due to their useful effect in enhancing advanced nano materials and components, which significantly improves the property of new mechatronics integrated materials and components. We performed a series of dry grinding experiments using a planetary ball mill to systematically investigate the grinding behavior during Al/CNTs nano composite fabrication. This study focused on a comparative study of the various experimental conditions at several variations of rotation speeds, grinding time and with and without CNTs. The results were monitored for the particle size distribution, median diameter, crystal structure from XRD pattern and particle morphology at a given grinding time. It was observed that pure aluminum powders agglomerated with low rotation speed and completely enhanced powder agglomeration. However, Al/CNTs composites were achieved at maximum experiment conditions (350 rpm, 60 min.) of this study by a mechanical alloy process for Al/CNTs mixed powders because the grinding behavior of Al/CNTs composite powder was affected by addition of CNTs. Indeed, the powder morphology and crystal size of the composite powders changed more by an increase of grinding time and rotation speed.

Carbon nanotubes-properties and applications: a review

Khalid Saeed Ibrahim 한국탄소학회 2013 Carbon Letters Vol.14 No.3

The carbon nanotube (CNT) represents one of the most unique inventions in the field of nanotechnology. CNTs have been studied closely over the last two decades by many researchers around the world due to their great potential in different fields. CNTs are rolled graphene with SP2 hybridization. The important aspects of CNTs are their light weight, small size with a high aspect ratio, good tensile strength, and good conducting characteristics, which make them useful as fillers in different materials such as polymers, metallic surfaces and ceramics. CNTs also have potential applications in the field of nanotechnology, nanomedicine, transistors, actuators, sensors, membranes, and capacitors. There are various techniques which can be used for the synthesis of CNTs. These include the arc-discharge method, chemical vaporize deposition (CVD), the laser ablation method, and the sol gel method. CNTs can be single-walled, double-walled and multi-walled. CNTs have unique mechanical, electrical and optical properties, all of which have been extensively studied. The present review is focused on the synthesis, functionalization, properties and applications of CNTs. The toxic effect of CNTs is also presented in a summarized form.

PHOTOCATALYTIC PROPERTIES OF TiO 2 /CNTs FILMS WITH DIFFERENT MORPHOLOGY ON STAINLESS STEEL SUBSTRATES

S. G. WANG,J. H. WANG,Z. R. DU,C. X. KONG,P. F. LI,C. X. WANG 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2014 NANO Vol.9 No.1

CNTs – TiO 2 ¯lms with di®erent morphology were fabricated on stainless steel substrates throughchemical vapor hydrolysis deposition (CVHD) process and sol – gel process, respectively. Theirmorphology was characterized by scanning electron microscopy (SEM) and transmission electronmicroscopy (TEM). The photocatalytic properties of the ¯lms were tested in the degradation ofmethyl orange by UV light irradiation. The results revealed that TiO 2 nanoparticles could form acontinuous layer on the surface of CNTs through CVHD process. While for sol – gel process, mostTiO 2 nanoparticles were isolated and only a small amount of TiO 2 nanoparticles attached on thesurface of CNTs. And the photocatalytic property of TiO 2 /CNTs ¯lm synthesized throughCVHD process was better than that of TiO 2 /CNTs ¯lms synthesized through sol – gel process. Electrochemical impedance spectroscopy (EIS) analysis illuminated that TiO 2 /CNTs synthesizedthrough CVHD process displayed a smaller resistance than the sample which was synthesizedthrough sol – gel process and certi¯ed that the close combination between TiO 2 and CNTs couldminimize recombination of photogenerated electrons and holes, and thus promote the photo-catalytic property.

약물반응 조절에 미치는 탄소나노튜브가 첨가된 하이드로젤의 불소화 영향

김지현(Ji-Hyun Kim),배태성(Tae-Sung Bae),이영석(Young-Seak Lee) 한국고분자학회 2015 폴리머 Vol.39 No.6

탄소나노튜브(carbon nanotubes, CNTs)가 첨가된 하이드로젤의 약물방출속도를 용이하게 조절하기 위하여 소수성 관능기를 가지는 불소화 처리를 실시하였다. 이때 약물방출속도를 조사하기 위한 모델 약물로서 지용성물질인 비타민 D3를 사용하였다. 하이드로젤의 불소화 반응이 CNT 첨가로 인하여 훨씬 용이하였으며, 이는 CNTs가 첨가되지 않은 하이드로젤과 비교하여 반응성이 1.6배 높았다. 비타민 D3가 첨가된 하이드로젤의 불소화 반응은 약물방출조절 효과를 크게 증가시켰다. 또한 CNTs가 첨가된 하이드로젤 표면에 증가된 불소함량은 초기약물방출속도의 조절에 영향을 주었다. 하이드로젤 표면 불소화가 증가할수록 비타민 D3와의 표면 반응으로 인하여 약물방출효율이 크게 증가하였다. Hydrogels containing carbon nanotubes (CNTs) were fluorinated with hydrophobic functional groups to control the drug releasing rate. Vitamin D3, a fat-soluble material, was used as the model drug to investigate the drug deliver rate. The hydrogel containing CNTs was fluorinated well due to the CNTs, and fluorinated hydrogels had 1.6 times greater reactivity than those of the hydrogels lacking CNTs. The fluorination of hydrogels containing vitamin D3 substantially increased the effect of drug releasing efficiency. Additionally, the increased fluorine contents of hydrogels containing CNTs had affected on controlling the initial drug releasing rate. The drug releasing efficiency was remarkably increased by more fluorination due to the reactivity of vitamin D3 with fluorinated hydrogel surface.

Localized Growth and Integration of Carbon Nanotubes on Micro-Hotplates

Doan Duc Chanh Tin,Dang Mau Chien,Danick Briand,Gregor Schurmann,Nicolaas F. de Rooij 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.5

This paper reports on the localized growth and integration of carbon nanotubes (CNTs) on micro-hotplates used as gas sensors. CNTs were grown directly on micro-hotplates coated with an optimized thickness of Ni catalyst by using the heat provided by the integrated micro-heater. The in uence of process parameters, such as the methane ow, the temperature and the growth time, was investigated to optimize the integration of the CNTs. We are developing Pt electrodes with a reduced gap by using e-beam lithography and investigating the application of an electric eld between these electrodes during CNTs growth to improve their electrical connection by orientating the direction of their growth to be perpendicular to the electrodes. This paper reports on the localized growth and integration of carbon nanotubes (CNTs) on micro-hotplates used as gas sensors. CNTs were grown directly on micro-hotplates coated with an optimized thickness of Ni catalyst by using the heat provided by the integrated micro-heater. The in uence of process parameters, such as the methane ow, the temperature and the growth time, was investigated to optimize the integration of the CNTs. We are developing Pt electrodes with a reduced gap by using e-beam lithography and investigating the application of an electric eld between these electrodes during CNTs growth to improve their electrical connection by orientating the direction of their growth to be perpendicular to the electrodes.

Effect of moving load on dynamics of nanoscale Timoshenko CNTs embedded in elastic media based on doublet mechanics theory

Alaa A. Abdelrahman,Rabab A. Shanab,Ismail Esen,Mohamed A Eltaher 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.44 No.2

This manuscript illustrates the dynamic response of nanoscale carbon nanotubes (CNTs) embedded in an elastic media under moving load using doublet mechanics theory, which not considered before. CNTs are modelled by Timoshenko beam theory (TBT) and a bottom to up modelling nano-mechanics is simulated by doublet mechanics theory to capture the size effect of CNTs. To explore the influence of the CNTs configurations on the dynamic behaviour, both armchair and zigzag configurations are considered. The governing equations of motion and the associated boundary conditions are obtained using the Hamiltonian principle. The Navier solution methodology is applied to obtain the solutions for both orientations. Free vibration and forced response under moving loads are considered. The accuracy of the developed procedure is verified by comparing the obtained results with available previous algorithms and good agreement is observed. Parametric studies are conducted to demonstrate effects of doublet length scale, CNTs configurations, moving load velocities as well as the elastic media parameters on the dynamic behaviours of CNTs. The developed procedure is supportive in the design and manufacturing of MEMS/NEMS made from CNTs.

Carbon nanotubes/aluminum composite as a hydrogen source for PEMFC

Yu, M.,Kim, M.,Yoon, B.,Oh, S.,Nam, D.H.,Kwon, H. Pergamon Press ; Elsevier Science Ltd 2014 International journal of hydrogen energy Vol.39 No.34

Al matrix composites reinforced with 0-5 vol. % carbon nanotubes (CNTs) were fabricated by spark plasma sintering (SPS) to examine their hydrogen generation properties from the hydrolysis of Al in 10 wt. % NaOH solution at room temperature. The 5 vol. % CNTs/Al composite exhibits a maximum hydrogen generation rate of 120 ml/min g, which is about 6 times higher than that of Al without CNTs due to the synergetic effects of the porous Al matrix, which has a large reaction area and galvanic corrosion between the Al matrix and the CNTs. The hydrogen gas generated from the hydrolysis of the CNTs/Al composite has high purity without any production of undesirable CO. PEMFC produced electricity at 10 A and 0.73 V for 13 min, with hydrogen generated from the hydrolysis of 3.5 g-5 vol. % CNTs/Al composite. The CNTs/Al composite was effectively used as a hydrogen source for PEMFC.

Fibrous network of highly integrated carbon nanotubes/MoO3 composite bundles anchored with MoO3 nanoplates for superior lithium ion battery anodes

Se Hwan Oh,Seong Mi Park,Dong-Won Kang,Yun Chan Kang,Jung Sang Cho 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.83 No.-

Fibrous network of highly-integrated CNTs/MoO3 composite bundle in which CNTs anchored with MoO3nanoplates was prepared by electrospinning process and subsequent simple heat-treatment. Byperforming the pre-acid-treatments of both CNTs and PAN, dipole-dipole interactions and hydrogenbonding between CNTs and PAN could form MoO2(acac)2-PAN-CNTs complex in a solution, which allowsfor the formation of a stable jet during electrospinning. Notably, by selectively removing PAN in as-spunfibers during heat-treatment, a highly integrated CNTs/MoO3 bundle network anchored with MoO3nanoplates was obtained. This unique CNTs/MoO3 percolation network makes it possible to achieve asuperior lithium ion storage performance by improving electrical conductivity and structure stability. Thus, the unique nanostructure has high discharge capacities of 972 mA h g 1 after 100 cycles at 1.0 A g 1and 905 mA h g 1 after 800 long-term cycles at 2.0 A g 1, when applied as anode materials for lithium-ionbatteries. The discharge capacities of 980, 920, 819, 742, 599, 484, and 374 mA h g 1 were observed atcurrent densities of 0.5, 1.0, 2.0, 3.0, 5.0, 7.0, and 10.0 A g 1, respectively.

Preparation and mechanical behaviors of graphene oxide/carbon nanotube-reinforced sodium carboxymethyl cellulose nanocomposites

손영래,박수진 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.0

Sodium carboxymethyl cellulose/graphene oxide/carbon nanotubes (CMC/GO/CNTs) nanocomposites were prepared by a simple solution mixing-evaporation method as a function of CNTs amount. As GO/CNTs complexes are formed, CNTs can be dispersed in water. X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to investigate the structural properties and morphologies, respectively. The mechanical properties of CMC/GO/CNTs nanocomposite films were analyzed by universal testing machine (UTM). Compared with pure CMC film and CMC/GO nanocomposite film, it was found that the mechanical properties of CMC/GO/CNTs nanocomposite films were enhanced with adding the CNTs.