Synthesis of bamboo-like carbon nanotubes by ethanol catalytic combustion technique

Availableonlineatwww.sciencedirect.comDIRECT#Transactions ofNonferrous MetalSociety of ChinaSciencePressTrans. Nonferrous Met. Soc. China 16(2006)s435-s437www.csu.edu.cn/ysxb/Synthesis of bamboo-like carbon nanotubes byethanol catalytic combustion techniqueCHENG Jin(程进)2, ZoU Xiao-ping(邹小平)2,LFei(李飞ZHANG Hong-dan(张红丹)2, REN Peng-fei(任鹏飞)21. Research Center for Sensor Technology, Beijing Information Technology Institute, Beijing 100101, CH2. Beijing Key Laboratory for Sensor, Beijing 100101, ChinaReceived 10 April 2006; accepted 25 April 2006Abstract: Bamboo-like carbon nanotubes were synthesized by ethanol catalytic combustion(ECC) technique with combustionmethod. Copper plate was employed as substrate, ethanol as carbon source, and iron chloride as catalyst precursor. Theblack powder was characterized by means of scanning electron microscopy, transmission electron microscopy and Ramanspectroscopy. The results show that the thinner bamboo like carbon nanotubes have a relatively good structure that the compartmentlayers are more regular, while the thicker carbon nanotubes have a relatively irregular bamboo-like structure; the proposed method isimple to synthesize bamboo-like carbon nanotubes and has some advantages, such as flexible synthesis conditions, simple setup, andenvironment-friendlyKey words: bamboo-like carbon nanotubes; ethanol catalytic combustion technique; compartment layersY-junction carbon nanotubes which were synthesized by1 Introductioncatalytic chemical vapor deposition at 1 000-1 200 C[7]. LIU et al[13 synthesized bamboo-like carbonSince the discovery of carbon nanotubes, there has nanotubes earlier by an ethanol thermal reductionbeen great interest in synthesizing carbon nanotubes due process. This was a method which utilized the reaction ofto their remarkable electrical and mechanical ethanol with magnesium in stainless autoclave at 600Cproperties[ 1-3]. Various shapes and structures of carbon that is, this reaction was conducted under high pressurenanotubes have been found, such as single-walled carbon These methods suffer from complex setup and rigorousnanotubes [4], multi-walled carbon nanotubes[5], synthesis conditionszigzag-shaped carbon nanotubes[6], Y-shaped carbonIn the present work the bamboo-like caronnanotubes[7 and bamboo-like carbon nanotubes [8]. nanotubes were synthesized by ethanol catalyticSome of them have been successfully synthesized by combustion(ECC) technique. A copper plate wasvarious growth methods, such as arc discharge, chemical employed as substrate, ethanol as carbon source, and ironvapor deposition and combustion approach[9, 10]. The chloride as catalyst precursor. The as-grown productscombustion approach utilizes the energy of flame to were characterized by means of scanning electronvarious carbon materials, such as microscopy (SEM), transmission electron microscopyC60/C70[11], single-walled carbon nanotubes[9], multi- (TEM)and Raman spectroscopywalled carbon nanotubes[10] and carbon nanowires[ 12]However, bamboo-like carbon nanotubes have not been 2 Experimentalsynthesized by combustion approach up to dateBamboo-like carbon nanotubes are tube likeIn a typical experiment, 0.01 mol iron chloride wasbamboos which have some compartment layers between dissolved in ethanol to form 1 mol/L iron chloridethe walls. SU et al[7] observed bamboo structure within solution. Then thYH+n A. 1 mol/L and中国煤化工Foundation item: Project(KI772013)supported by the Science and Technology DevelopiCNMHGof Beijing CitProject(2supported by the Academic Innovative Team Porgram(Novettee of Beijing Cityresponding author: ZoUg;Tel:+86-10-64884673-812;Fax:+86-10-64879486;E-mail:xpzou2005@gmail.comCHENG Jin, et al/Trans. Nonferrous Met. Soc. China 16(2006)0.01 mol/L solution which was employed as catalyst while the thicker carbon nanotubes have a relativelyprecursor. A round copper plate with diameter of I cm, irregular bamboo-like structure, as the bamboo-likewhich was employed as substrate, was ultrasonically carbon nanotubes shown in Fig. 2washed in acetone for several minutes to clean thesurface of plateAfter drying, the catalyst precursor solution wasapplied to the clean surface of the copper plate. Then thecopper substrate was baken at 60 C for several minutesto remove the solvent. After that, the substrate wasplaced in inner flame for about 10 min. Then blackwool-like products were obtained. This process isethanol catalytic combustion technique mentioned aboveof carbon nanotubes was conducteddirectly in atmosphere and produced no pollutionThe black wool-like powder was characterized byJEOL 6500F SEM. JEM-200cx TEM and Rainshawoptical confocal Raman spectrometer.3 Results and discussion10 nm_25mFig 1 shows the SEM micrograph of a typical Fig.2 TEM images of carbon nanotubes grown on coppersample of carbon nanotubes grown on copper substratesubstrate with 0.01 mol/L iron chloride catalyst precursorwith 0.01 mol/L iron chloride catalyst precursor for (arrows mark compartment layers: arrows @markbout 10 min synthesis duration, indicating the largeowth directionquantity of carbon nanotubes were achieved by using thisapproach. These carbon nanotubes have diametersFig 3 shows the Raman spectrum of carbonranging from about 10 to 60 nm and lengths ranging nanotubes which was obtained with a REINSHAWfrom hundreds of nanometers to several micrometersoptical confocal Raman microscope. The sampleexcitation was performed using 5 mW of 514.5 nm laserwith 3 um spot size. The spectrum shows the peakI cm(G)andcontains disordered modes at 1 345 cm"(D).Whencompared with the raman spectra of carbon nanotubessynthesized by other methods, such as arc discharge[ 14and chemical vapor deposition [15], the present Ramanspectrum obviously gives the large ratio of Ip/IG. Thisphenomenon illustrates that the carbon nanotubessynthesized by ECC technique have a lot of disorder struc159SE 04-Jan-06IPC WD152mm 10.0kv x20k 2uFig 1 SEM image of carbon nanotubes grown on coppersubstrate with 0.01 mol/L iron chloride catalyst precursor forabout 10 minFig 2 shows the TEM images of carbongrown with 0.01 mol/L iron chloride catalyst precursorFig 2 (a) shows the carbon nanotube has a bamboo-likestructure clearly. The black arrows in Fig. 2(a)markthe compartment layers. Fig. 2(b) shows the compart-ment layers(see arrows )whose curvature is directedtoward the growth direction(see arrows 2).The thinnerbamboo-like carbon nanotubes have a relatively good Fig 3 RamanYH中国煤化工2000CN MH Gown on coppestructure whose the compartment layers are more regular, substrate with 0.0l mol/L iron chloride catalyst precursorCHENG Jin, et al/Trans. Nonferrous Met. Soc. China 16(2006)437ture or defects[ 16]. We speculate that it is related to its ethanol catalytic combustion technique with 0.01 mol/Lunique synthesis conditions in atmospherand 0.1 mol/L iron chloride catalyst precursor. TheFig 4 shows the TEM images of carbon nanotubes morphology and microstructure of bamboo-like carbby employing 0. 1 mol/L iron chloride catalyst precursors. nanotubes are affected by catalyst size which is related toThe carbon nanotubes with diameter of about 40 nm concentration of catalyst precursor. The thinnershown in Fig 4 have a clear bamboo-like structure. While bamboo-like carbon nanotubes have a relatively goodfor 1 mol/L iron chloride catalyst precursor it is found structure whose the compartment layers are more regularis no carbon nanotubes except solid carbon while the thicker carbon nanotubes have a relativelywith diameter ranging from about 50 to 150 irregular bamboo-like structure. In summary, this is anm.simple method to synthesize bamboo-like carbonnanotubes due to synthesizing directly in atmosphere andthere are some advantages, such as simple setup, flexiblesynthesis condition, and enviroment-friendlyReferences[1 IUJIMA S Helical microtubules of graphitic carbon[J]. Nature. 199354:56-58[2] ZOU X P, ABE H, SHIMIZU T, ANDO A, NAKAYAMA YTOKUMOTO H, ZHU S M, ZHOU H S Simple thermal chemicaldeposition synthesis and electrical property of multi-wallednanotubes[J]. Physica E, 2004, 24: 14-18[3Z W, XIE SS, CHANG B H, WANG C Y, LU L, et al. Verylong carbon nanotubes[J]. Nature, 1998, 394: 631-632.[4 HATA K, FUTABA N D, MIZUNO K, NAMAI T, YUMURA M,50 nmIIJIMA S. Water-assisted highly efficient synthesis of impurity-freesingle-walled carbon nanotubes[J]. 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