Carbon Science Vol. 7, No. 4 December 2006 pp. 277-281 Synthesis and Properties of Dual Structured Carbon Nanotubes (DSCNTs) Se-Ho Cho 1, Do-Yoon Kim 1, Jeong-Ku Heo 1,, Young-Hee Lee 2, Kay-Hyeok An 2,3, Shin-Dong Kim 4 and Young-Seak Lee 4 1 Nano Karbon Inc., Sungkyunkwan University, Suwon 440-746, Korea 2 Department of Nanoscience and Nanotechnology, BK21 Physics Division, Center for Nanotubes and Nanostructured Composites, Sungkyunkwan University, Suwon 440-746, Korea 3 Jeonju Machinary Research Center, Palbok-dong, 2-ga, 750-1, Jeonju, Korea 4 Department of Fine Chemical Engineering and Chemistry, Chungnam National University, Daejeon 305-764, Korea e-mail: nkmaster@nanokarbon.co.kr (Received September 25, 2006; Accepted December 11, 2006) Abstract In this study, in order to easily provide functional groups on the surface of carbon nanotubes, dual structural multiwalled carbon nanotubes which have crystalline graphite and turbostratic carbon wall were synthesized by modified vertical thermal decomposition method. Synthesized dual structural MWCNTs were characterized by FE-SEM, TGA, HR-TEM, Raman spectroscopy and BET specific surface area analyzer. The average innermost and outermost diameters of the synthesized nanotubes were around 45 and 75 nm, respectively. The large empty inner space and the presence of graphitic carbons on the surface may open potential applications for gas storage and collection of hazardous materials. Keywords : Carbon nanotube, Dual structure, MWCNT, Gas storage, Functional group 1. ˆ 1991 Iijima l p r re l p l p q v l kl p l v l m [1]. ˆ l (graphite sheet) p s f, chiralityl armchair zigzag t ˆp chiral s v, p sr p ˆ p r, lr, r r k r vl m p. ˆ v r p v, EMI(rqŽ ), r, l v rq ~, ~, rq q, rq q p k l pnp p pp l q v tp [2-10]. ˆ p l v pn kl rn o l p p l l p v p. ˆ p pn o v lˆm p n l p p ˆ p p n p erp. p o, v,, ms, p pn r m l v r pn ˆ p l v p p [11-13]. v sp p ˆ l p pp sv kk r n l ps p. r k pn kl qn n pl nl rrp p., l q p ˆ p p pnp o l k l pp, d pn l sp edge l l l l ˆ r~l l fluorination, oxy-fluorination v rk l [14-16]. ˆ p r, p lr r kr p v e p o s l m p t p k r p [17]. v ˆ sr kr p p l p p lv, ˆ p (side-wall)p turbostatic amorphous s ˆ p ˆ oqm s v p p p v pl e p l s v p p n p Ž., l ˆ p pn o l rp n lp l t r p pt s ˆ rs q m. p ˆ p r/ r p k p l m.
278 S.-H. Cho et al. / Carbon Science Vol. 7, No. 4 (2006) 277-281 2. w l l sl q k v v q q mp, ironpentacarbonyl (liquid, Fe(CO) 5 ) p n m. p n l p ironpentacarbonylp n p f l p p p m. p p purgingp ~p Ar (99.99%)p mp, purging m ˆp ironpentacarbonyl C 2 H 2 700-1000 o C o v p l 45 ml/hr pumping l m. n ironpentacarbonylp m 105 o Cp 250 o Cl eq. ˆ Fe o q l cluster p p l sq t ˆ m p l ˆ. p y pt s ˆ (dual structure carbon nanotubes, DSCNTs)p ˆr s SEM(Scanning Electron Microscope, Hitachi, S-3500N)p l, lt (Thermogravimetric Analysis, TGA) l ˆ p p kk k. DSCNTsp l s r XRD(X-ray Diffractometry, MacScience, M18XHF-SRA) pn l r m. l s l rp r Raman spectroscopy(jobin YVON, T64000) l m. s p 120 k 2 cycle r mp, 514.532 nm Žq 1 mw Žop pr pn l r m., l ˆ p sm ˆ p o l HRTEM(High Resolution Transmission Electron Microscopy)p pn l p ee m. ˆ p s rp r o l 77 Kl BET r r q (Micromeritics, ASAP 2020) n m. 3. y Fig. 1p e l ˆ p SEM vp llv p p. Fig. 1(a)l ˆ p qq (edge) n Fe l. rs ˆ p p 20 μm p p, v p 70~80 nmp p p l. Fig. 1(b) ˆ 50,000 SEM vp ˆ Ž p l p l n p p ˆ p p lt p. Fig. 1(b)l k p p, ˆ p v p p p l. Fig. 1(b)l lt m p p p p, tp v q p. l l l tp p q m. v, sq ˆ Žp o m lp ~ q p k p [18, 19]., Zhixin Yu p l v r ~ rs ~ (FE) l p p q l l m [20]. e l Fe(CO) 5 r ~ Fe l t ˆ p lr p Fig. 2l lt p. p p o p 5 cc/minp, d m 5 o C/min l m. p q k v ˆ p Fig. 2(a)m (b)l 773.15 K p l eq p p plp, 873.15 K prl t r ˆ p ˆ p Ž p. Fig. 2(a)l 892.15 K }l t p l p p p p p ˆ p Fig. 1. SEM images of dual structural MWCNTs.
Synthesis and Properties of Dual Structured Carbon Nanotubes (DSCNTs) 279 Fig. 2. Thermograms of dual structural MWCNTs. p p p rv ˆ p pl l p (873.15 K) p p. t ˆ p m -t rv ˆ p ml w p p pp p p t ˆ tl r p kp r p l rp rp p Ž. v, e s l rs t ˆ p r p p Ž., Fig. 2(b)p lt l 886.15 Km 894.15 Kl p lr ˆ p, p t ˆ l vp ˆp p sq p k p. 873.15 K l }p ˆ p rp l p d p pp w 894.15 K l ˆ l d v k s ˆp p sq p pp t s ˆ p sp p p e l m p lt p l v. l l t ˆ p sm n p s p pt sp ˆ Ž, p p Fig. 3p TEM sl k p. Fig. 3p pt s t ˆ p TEM vp. Fig. 3(a), (b)l lp t s p p pp, ƒp ~ o p ˆp U q p p p v kp, kp Fig. 1p SEM vl m p le p p v k l p p p [21]. Fig. 3(b) p s o l Fig. 3(a) l ˆ vp. p tp yp k 2/3vr v q l p pp v n v q l ˆp ˆ p p p. kp lt m l ˆ e y ˆ p p rp r ˆ p sm s ˆ p. p 883.15 K l ˆ p p r ˆ ˆp ol l p TEM vl p p lt p p. n le ll n ˆp s p l rp Ž. Fig. 4(a)p pt s t ˆ p X r Ž p lt p. 26.7 o l r rp l r ˆ p pp k 43 o ~47 o pl Fe 3 C p p ˆ. p p kr p p rr rp d r [22]. pt s t ˆ p r ˆ kk o Raman n l d p Fig. 4(b)l ˆ l, 1571 cm 1 p r rp l s lt l m p l s ˆ 1347 cm 1 l ˆ p p. p ˆ Fig. 3. TEM images of dual structural MWCNTs.
280 S.-H. Cho et al. / Carbon Science Vol. 7, No. 4 (2006) 277-281 Fig. 4. XRD pattern and Raman spectrum of dual structural MWCNTs. Fig. 5. N 2 adsorption isotherm at 77 K of dual structural MWCNTs. kyl q l yp p lp s, v p s v ˆ p p p, kl TEM l t q p p k p., e l pt s t ˆ p s p kk o l N 2 ~p p l m. Fig. 5 77 Kl pt s t ˆ p N 2 m p ˆ p. Fig. 5l l t m p, pt s t ˆ p m p IUPAC t /ˆ p d ed l t p r rp Type p ˆ ˆ ppp p pl [23]. Fig. 5(a)l lt pt s t ˆ Fig. 6. Pore size distribution of dual structural MWCNTs. p m BET p pn l r Table 1l ˆ l. pt s t ˆ p rp p rp t ˆ m o 133 m 2 /gp mlp r~ BET r p k 59% r v pp v s n r(external surface area)p ˆ., Fig. 6 p rs pt s t ˆ p lt p. Fig. 6l m p pt s t ˆ p p 50 nm p l p l p p pp p p pt s t ˆ p n pp t 20 nm p p p k v p 70~80 nm p Ž p, p k l SEM TEM m p p p k p. Table 1. N 2 adsorption characteristics of the DSCNTs BET surface area (m 2 /g) Micropore area (m 2 /g) Micropore ratio (%) Micropore volume (cm 3 /g) Average pore width (nm) DSCNTs 133 78 58.6 0.035 13.1
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