Large-scale and controllable synthesis of metal-free nitrogen-doped carbon nanofibers and nanocoils over water-soluble Na2CO3
© Ding et al.; licensee Springer. 2013
Received: 11 July 2013
Accepted: 17 December 2013
Published: 27 December 2013
Using acetylene as carbon source, ammonia as nitrogen source, and Na2CO3 powder as catalyst, we synthesized nitrogen-doped carbon nanofibers (N-CNFs) and carbon nanocoils (N-CNCs) selectively at 450°C and 500°C, respectively. The water-soluble Na2CO3 is removed through simple washing with water and the nitrogen-doped carbon nanomaterials can be collected in high purity. The approach is simple, inexpensive, and environment-benign; it can be used for controlled production of N-CNFs or N-CNCs. We report the role of catalyst, the effect of pyrolysis temperature, and the photoluminescence properties of the as-harvested N-CNFs and N-CNCs.
KeywordsCarbon materials Chemical vapor deposition Water-soluble Nitrogen-doped
Since Iijima’s paper on helical carbon nanotubes, carbon nanomaterials (CNM) such as carbon nanotubes (CNT) and carbon nanofibers (CNF) have attracted great attention for their unique and outstanding electrical and mechanical properties [1–4]. The helical CNT are composed of five-membered or seven-membered rings, having carbon atoms of sp2 and sp3 hybridization [5, 6]. It is envisaged that helical CNT exhibit novel and peculiar properties that are different from those of linear CNT. It has been suggested that CNM can be utilized in hydrogen storage [7, 8], microwave absorption , and field emission [10, 11]. Using CNM, scientists tried to fabricate nanosized electromagnetism devices [12–14] such as solenoid switch [15, 16], miniature antenna [17, 18], energy converter [19, 20], and sensor [21, 22].
For CNM generation, methods such as arc discharge, laser ablation, hydrothermal carbonization, solvothermal reduction, and chemical vapor deposition (CVD) are used [23–28]. Nonetheless, it is common to have metal impurities in the products, and the intrinsic properties of the as-obtained CNM are uncertain. The problem of metal impurities hinders further researches on CNM especially those related to electromagnetism features [29, 30]. It is tedious and costly to remove metal impurities such as those of iron-group elements or their alloys . Furthermore, unexpected defects or contaminants could be introduced into the CNM during purification procedures.
As a traditional method, CVD has its advantages [32, 33]. By regulating parameters such as catalyst amount, reaction temperature, source flow rate, one can obtain different kinds of CNM. It is possible to control the CVD process for a designated outcome by adopting a particular set of reaction conditions [34, 35]. Using acetylene as carbon precursor, Amelinckx et al. , Nitze et al. , and Tang et al.  obtained CNM with high purity and selectivity. Nevertheless, there are disadvantages such as high reaction temperature and outgrowth of desired product [28, 39]. As for the growth mechanism of CNT in CVD processes, there are still controversies [40, 41].
By doping foreign elements such as nitrogen and boron into the graphite lattices of CNM, Wang et al. , Ayala et al. , and Koós et al.  induced crystal and electronic changes to the structures of CNM [42–44]. It is noted that as support for palladium nanoparticles, helical CNM show excellent properties in electro-catalytic applications [45, 46]. According to Franceschini et al.  and Mandumpal et al. , the introduction of nitrogen restrains the aggregation of vacancies, resulting in defects and dislocations, as well as amplified curvature of graphite planes. The results of both experimental and theoretical studies demonstrate that compared to pure CNT, nitrogen-doped CNT show enhanced field emission properties and there is a shift of the dominant emission towards lower energies [49–51]. Through theoretical studies of heteroatom-substituted graphite systems, Hagiri et al. suggested that different heteroatom arrangements cause different spin-stable singlet and triplet states and that the substituted nitrogen atom as a spin cap induces the π electron excess . When it comes to CNT utilization, high incorporation of nitrogen is desirable in promoting porosity and electrochemical reactivity of CNT. On the other hand, if CNT are supposed to be applied in semiconductor technology, low nitrogen-doping density is necessary.
Recently, we reported the large-scale synthesis of various kinds of non-doped CNM that are metal-free [53–55]. Herein, we report the use of Na2CO3 as catalyst for the selective formation of nitrogen-doped CNF (N-CNF) and nitrogen-doped CNC (N-CNC). We used Na2CO3 because it is water-soluble and can be removed from N-CNM through steps of water washing. We found that the Na2CO3 catalyst prepared by us is active and selective for mass formation of N-CNF and N-CNC. By means of CVD using Na2CO3 as catalyst, high-purity N-CNM can be obtained after washing the products with deionized water and ethanol. The approach is simple, inexpensive, and environment-benign, and can be used for mass production of high-purity N-CNF and N-CNC.
All materials used were commercially available and analytically pure. In the present study, we employed Na2CO3 as catalyst. First, we mixed 10 g of Na2CO3 (in powder form) in 200 ml of deionized water at room temperature (RT) with continuous stirring. Once a transparent solution was obtained, the solution was kept at 80°C for several hours and allowed to cool down to RT for the precipitation of a white powder. The powder was filtered out, dried, and ground into tiny particles.
We placed 0.5 g of catalyst at the center of a ceramic boat with two open ends. The boat was then put inside a quartz tube with a thermocouple attached to its center. For the CVD reaction, we used acetylene as carbon source and ammonia as nitrogen source. After the reaction chamber was purged with argon for the elimination of oxygen, the sources were introduced into the system at either 450°C or 500°C at a C2H2/NH3 flow rate ratio of 1:1 for 6 h. To study the effect of changing the flow rate ratio, we also introduced acetylene and ammonia at a C2H2/NH3 flow rate ratio of 5:1 at 450°C for 6 h. After the reaction, argon was again introduced to protect the product from oxidation until the system was cooled down to RT. To remove the catalyst and to avoid organic outgrowth, the as-obtained products were repeatedly washed with deionized water and ethanol. Compared to the methods commonly used for CNM purification, the one used in the present study causes no damage to the desired product.
The morphologies of samples were examined using a transmission electron microscope (TEM) operated at an accelerating voltage of 200 kV and a field emission scanning electron microscope (FE-SEM) operated at an accelerating voltage of 5 kV. Fourier transform infrared (FTIR) spectroscopic studies of samples (in KBr pellets) were conducted over a Nocolet 510P spectrometer (Thermo Nocolet, Stanford, CT, USA). The surface analysis of products was carried out by means of X-ray photoelectron spectroscopy (XPS, PHI 5000 VersaProbe, UIVAC-PHI Inc., Chigasaki, Kanagawa, Japan). The products were examined on an X-ray powder diffractometer (XRD) at RT for phase identification using CuKα radiation (model D/Max-RA, Rigaku Corporation, Tokyo, Japan). Raman spectroscopic investigations were performed over a Jobin-Yvon Labram HR800 instrument (Horiba, Ann Arbor, MI, USA) with 514.5-nm Ar laser excitation. The photoluminescence (PL) spectra were collected at RT over a spectrofluorophotometer (Shimadzu RF-5301 PC; Shimadzu Co. Ltd., Beijing, China) using a Xe lamp as light source. For PL investigation, about 0.1 mg of sample was ultrasonically dispersed in 5 ml of deionized water. Thermoanalysis was carried out using a thermal analysis system (NETZSCH STA 449C; NETZSCH Company, Shanghai, China) with the sample heated in air at a rate of 20°C/min.
Results and discussion
Preparation summary of samples
Reaction temperature (°C)
Flow rate ratios (C2H2/NH3)
Nitrogen content of samples
Nitrogen content (at.%)
The I G / I D intensity ratios of all samples
Compared with C5N1, C450N is lower in IG/ID value. The C2H2/NH3 flow rate ratio for the formation of C5N1 is 5:1 whereas that of C450N is 1:1. In other words, with a source flow richer in nitrogen, there is rise of nitrogen content, and with more defects or vacancies in N-CNM, there is decline of IG/ID value. With the rise of reaction temperature from 450°C to 500°C, there is slight decrease of nitrogen content but enhanced formation of amorphous carbon, and the net result is the further decline of IG/ID value.
By controlling the acetylene decomposition temperature, N-CNF and N-CNC can be selectively synthesized in large scale over Na2CO3. Due to the water-soluble property of NaCO3, the products can be obtained in high purity through steps of water and ethanol washing. The CVD process using Na2CO3 as catalyst is simple, inexpensive, and environment-benign. We detect graphitic, pyridine-like as well as pyrrole-like N species in the nitrogen-doped CNM. Compared to the non-doped pristine CNM, the nitrogen-doped ones show enhanced UV PL intensity.
This work was supported by the National Natural Science Foundation of China (grant no. 11174132), the National Key Project for Basic Research (grant nos. 2010CB923402 and 2011CB922102), and PAPD, People’s Republic of China.
- Iijima S: Helical microtubules of graphitic carbon. Nature 1991, 354: 56–58. 10.1038/354056a0View ArticleGoogle Scholar
- Iijima S, Ichihashi T: Single-shell carbon nanotubes of 1-nm diameter. Nature 1993, 363: 603–605. 10.1038/363603a0View ArticleGoogle Scholar
- Bethune DS, Johnson RD, Salem JR, Devries MS, Yannoni CS: Atoms in carbon cages - the structure and properties of endohedral fullerenes. Nature 1993, 366: 123–128. 10.1038/366123a0View ArticleGoogle Scholar
- Rodriguez NM, Chambers A, Baker RTK: Catalytic engineering of carbon nanostructures. Langmuir 1995, 11: 3862–3866. 10.1021/la00010a042View ArticleGoogle Scholar
- Tamura R, Tsukada M: Electronic states of the cap structure in the carbon nanotube. Phys Rev B 1995, 52: 6015–6026. 10.1103/PhysRevB.52.6015View ArticleGoogle Scholar
- Terrones H, Terrones M, Hernandez E, Grobert N, Charlier JC, Ajayan PM: New metallic allotropes of planar and tubular carbon. Phys Rev Lett 2000, 84: 1716–1719. 10.1103/PhysRevLett.84.1716View ArticleGoogle Scholar
- Tans SJ, Verschueren ARM, Dekker C: Room-temperature transistor based on a single carbon nanotube. Nature 1998, 393: 49–52. 10.1038/29954View ArticleGoogle Scholar
- Bai XD, Zhong DY, Zhang GY, Ma XC, Liu S, Wang EG, Chen Y, Shaw DT: Hydrogen storage in carbon nitride nanobells. Appl Phys Lett 2001, 79: 1552–1554. 10.1063/1.1402958View ArticleGoogle Scholar
- Wadhawan A, Garrett D, Perez JM: Nanoparticle-assisted microwave absorption by single-wall carbon nanotubes. Appl Phys Lett 2003, 83: 2683–2685. 10.1063/1.1615679View ArticleGoogle Scholar
- Adessi C, Devel M: Theoretical study of field emission by single-wall carbon nanotubes. Phys Rev B 2000, 62: 13314–13317. 10.1103/PhysRevB.62.R13314View ArticleGoogle Scholar
- Shim M, Javey A, Kam NWS, Dai HJ: Polymer functionalization for air-stable n-type carbon nanotube field-effect transistors. J Am Chem Soc 2001, 123: 11512–11513. 10.1021/ja0169670View ArticleGoogle Scholar
- Dai HJ, Hafner JH, Rinzler AG, Colbert DT, Smalley RE: Nanotubes as nanoprobes in scanning probe microscopy. Nature 1996, 384: 147–150. 10.1038/384147a0View ArticleGoogle Scholar
- Tsukagoshi K, Alphenaar BW, Ago H: Coherent transport of electron spin in a ferromagnetically contacted carbon nanotube. Nature 1999, 401: 572–574. 10.1038/44108View ArticleGoogle Scholar
- Yang CK, Zhao J, Lu JP: Magnetism of transition-metal/carbon-nanotube hybrid structures. Phys Rev Lett 2003, 90: 257203.View ArticleGoogle Scholar
- Liu L, Jayanthi CS, Tang MJ, Wu SY, Tombler TW, Zhou CW, Alexseyev L, Kong J, Dai H: Controllable reversibility of an sp(2) to sp(3) transition of a single wall nanotube under the manipulation of an AFM tip: a nanoscale electromechanical switch? Phys Rev Lett 2000, 84: 4950–4953. 10.1103/PhysRevLett.84.4950View ArticleGoogle Scholar
- Banerjee P, Wolny F, Pelekhov DV, Herman MR, Fong KC, Weissker U, Muhl T, Obukhov Y, Leonhardt A, Buchner B, Hammel PC: Magnetization reversal in an individual 25 nm iron-filled carbon nanotube. Appl Phys Lett 2010, 96: 252505–252505. -3 -3 10.1063/1.3440951View ArticleGoogle Scholar
- Dresselhaus MS: Applied physics - nanotube antennas. Nature 2004, 432: 959–960. 10.1038/432959aView ArticleGoogle Scholar
- Kempa K, Rybczynski J, Huang ZP, Gregorczyk K, Vidan A, Kimball B, Carlson J, Benham G, Wang Y, Herczynski A, Ren ZF: Carbon nanotubes as optical antennae. Adv Mater 2007, 19: 421. 10.1002/adma.200601187View ArticleGoogle Scholar
- Zhang J, Hu YS, Tessonnier JP, Weinberg G, Maier J, Schlogl R, Sheng DS: CNFs@CNTs: superior carbon for electrochemical energy storage. Adv Mater 2008, 20: 1450. 10.1002/adma.200701685View ArticleGoogle Scholar
- Guldi DM, Sgobba V: Carbon nanostructures for solar energy conversion schemes. Chem Commun 2011, 47: 606–610. 10.1039/c0cc02411bView ArticleGoogle Scholar
- Baughman RH, Zakhidov AA, de Heer WA: Carbon nanotubes - the route toward applications. Science 2002, 297: 787–792. 10.1126/science.1060928View ArticleGoogle Scholar
- Kong J, Franklin NR, Zhou CW, Chapline MG, Peng S, Cho KJ, Dai H: Nanotube molecular wires as chemical sensors. Science 2000, 287: 622–625. 10.1126/science.287.5453.622View ArticleGoogle Scholar
- Loiseau A, Willaime F, Demoncy N, Hug G, Pascard H: Boron nitride nanotubes with reduced numbers of layers synthesized by arc discharge. Phys Rev Lett 1996, 76: 4737–4740. 10.1103/PhysRevLett.76.4737View ArticleGoogle Scholar
- Journet C, Maser WK, Bernier P, Loiseau A, delaChapelle ML, Lefrant S, Deniard P, Lee R, Fischer JE: Large-scale production of single-walled carbon nanotubes by the electric-arc technique. Nature 1997, 388: 756–758. 10.1038/41972View ArticleGoogle Scholar
- Liu ZP, Zhou XF, Qian YT: Synthetic methodologies for carbon nanomaterials. Adv Mater 2010, 22: 1963–1966. 10.1002/adma.200903813View ArticleGoogle Scholar
- Sawant SY, Somani RS, Bajaj HC: A solvothermal-reduction method for the production of horn shaped multi-wall carbon nanotubes. Carbon 2010, 48: 668–672. 10.1016/j.carbon.2009.10.008View ArticleGoogle Scholar
- Ebbesen TW, Ajayan PM: Large-scale synthesis of carbon nanotubes. Nature 1992, 358: 220–222. 10.1038/358220a0View ArticleGoogle Scholar
- Cassell AM, Raymakers JA, Kong J, Dai HJ: Large scale CVD synthesis of single-walled carbon nanotubes. J Phys Chem B 1999, 103: 6484–6492. 10.1021/jp990957sView ArticleGoogle Scholar
- Banks CE, Crossley A, Salter C, Wilkins SJ, Compton RG: Carbon nanotubes contain metal impurities which are responsible for the “electrocatalysis” seen at some nanotube-modified electrodes. Angew Chemie-Int Ed 2006, 45: 2533–2537. 10.1002/anie.200600033View ArticleGoogle Scholar
- Jones CP, Jurkschat K, Crossley A, Compton RG, Riehl BL, Banks CE: Use of high-purity metal-catalyst-free multiwalled carbon nanotubes to avoid potential experimental misinterpretations. Langmuir 2007, 23: 9501–9504. 10.1021/la701522pView ArticleGoogle Scholar
- Park TJ, Banerjee S, Hemraj-Benny T, Wong SS: Purification strategies and purity visualization techniques for single-walled carbon nanotubes. J Mater Chem 2006, 16: 141–154. 10.1039/b510858fView ArticleGoogle Scholar
- Leal MCA, Horna CD: CVD and the new technologies. An Quim 1991, 87: 445–456.Google Scholar
- Li QW, Yan H, Cheng Y, Zhang J, Liu ZF: A scalable CVD synthesis of high-purity single-walled carbon nanotubes with porous MgO as support material. J Mater Chem 2002, 12: 1179–1183. 10.1039/b109763fView ArticleGoogle Scholar
- Kong J, Zhou C, Morpurgo A, Soh HT, Quate CF, Marcus C, Dai H: Synthesis, integration, and electrical properties of individual single-walled carbon nanotubes. Appl Phys A Mater Sci Process 1999, 69: 305–308. 10.1007/s003390051005View ArticleGoogle Scholar
- Su M, Zheng B, Liu J: A scalable CVD method for the synthesis of single-walled carbon nanotubes with high catalyst productivity. Chem Phys Lett 2000, 322: 321–326. 10.1016/S0009-2614(00)00422-XView ArticleGoogle Scholar
- Amelinckx S, Zhang XB, Bernaerts D, Zhang XF, Ivanov V, Nagy JB: A formation mechanism for catalytically grown helix-shaped graphite nanotubes. Science 1994, 265: 635–639. 10.1126/science.265.5172.635View ArticleGoogle Scholar
- Nitze F, Abou-Hamad E, Wagberg T: Carbon nanotubes and helical carbon nanofibers grown by chemical vapour deposition on C60 fullerene supported Pd nanoparticles. Carbon 2010, 49: 1101–1109.View ArticleGoogle Scholar
- Tang NJ, Wen JF, Zhang Y, Liu FX, Lin KJ, Du YW: Helical carbon nanotubes: catalytic particle size-dependent growth and magnetic properties. ACS NANO 2010, 4: 241–250. 10.1021/nn901425rView ArticleGoogle Scholar
- Li YY, Sakoda A: Growth of carbon nanotubes and vapor-grown carbon fibers using chemical vapor deposition of methane. J Chin Inst Chem Eng 2002, 33: 483–489.Google Scholar
- Lee CJ, Lyu SC, Cho YR, Lee JH, Cho KI: Diameter-controlled growth of carbon nanotubes using thermal chemical vapor deposition. Chem Phys Lett 2001, 341: 245–249. 10.1016/S0009-2614(01)00481-XView ArticleGoogle Scholar
- Emmenegger C, Bonard JM, Mauron P, Sudan P, Lepora A, Grobety B, Züttela A, Schlapbach L: Synthesis of carbon nanotubes over Fe catalyst on aluminium and suggested growth mechanism. Carbon 2003, 41: 539–547. 10.1016/S0008-6223(02)00362-7View ArticleGoogle Scholar
- Wang B, Ma YF, Wu YP, Li N, Huang Y, Chen YS: Direct and large scale electric arc discharge synthesis of boron and nitrogen doped single-walled carbon nanotubes and their electronic properties. Carbon 2009, 47: 2112–2115. 10.1016/j.carbon.2009.02.027View ArticleGoogle Scholar
- Ayala P, Arenal R, Rummeli M, Rubio A, Pichler T: The doping of carbon nanotubes with nitrogen and their potential applications. Carbon 2010, 48: 575–586. 10.1016/j.carbon.2009.10.009View ArticleGoogle Scholar
- Koós AA, Dillon F, Obraztsova EA, Crossley A, Grobert N: Comparison of structural changes in nitrogen and boron-doped multi-walled carbon nanotubes. Carbon 2010, 48: 3033–3041. 10.1016/j.carbon.2010.04.026View ArticleGoogle Scholar
- Hu GZ, Nitze F, Sharifi T, Barzegar HR, Wagberg T: Self-assembled palladium nanocrystals on helical carbon nanofibers as enhanced electrocatalysts for electro-oxidation of small molecules. J Mater Chem 2012, 22: 8541–8548. 10.1039/c2jm16075gView ArticleGoogle Scholar
- Hu GZ, Nitze F, Barzegar HR, Sharifi T, Mikolajczuk A, Tai CW, Borodzinski A, Wågberg T: Palladium nanocrystals supported on helical carbon nanofibers for highly efficient electro-oxidation of formic acid, methanol and ethanol in alkaline electrolytes. J Power Sources 2012, 209: 236–242.View ArticleGoogle Scholar
- Franceschini DF, Achete CA, Freire FL: Internal-stress reduction by nitrogen incorporation in hard amorphous-carbon thin-films. Appl Phys Lett 1992, 60: 3229–3231. 10.1063/1.106702View ArticleGoogle Scholar
- Mandumpal J, Gemming S, Seifert G: Curvature effects of nitrogen on graphitic sheets: structures and energetics. Chem Phys Lett 2007, 447: 115–120. 10.1016/j.cplett.2007.09.007View ArticleGoogle Scholar
- Wang XB, Liu LQ, Zhu DB, Zhang L, Ma HZ, Yao N, Zhang B: Controllable growth, structure, and low field emission of well-aligned CN x nanotubes. J Phys Chem B 2002, 106: 2186–2190. 10.1021/jp013007rView ArticleGoogle Scholar
- Wang C, Qiao L, Qu CQ, Zheng WT, Jiang Q: First-principles calculations on the emission properties of pristine and N-doped carbon nanotubes. J Phys Chem C 2009, 113: 812–818. 10.1021/jp809277wView ArticleGoogle Scholar
- Li LJ, Glerup M, Khlobystov AN, Wiltshire JG, Sauvajol JL, Tavlor RA, Nicholas RJ: The effects of nitrogen and boron doping on the optical emission and diameters of single-walled carbon nanotubes. Carbon 2006, 44: 2752–2757. 10.1016/j.carbon.2006.03.037View ArticleGoogle Scholar
- Hagiri I, Takahashi N, Takeda K: Theoretical possibility of the variety of ground-state spin arrangements created by the spin hole and spin cap in a pi-conjugated system. J Phys Chem A 2004, 108: 2290–2304. 10.1021/jp0307102View ArticleGoogle Scholar
- Qi XS, Ding Q, Zhang H, Zhong W, Au C, Du YW: Large-scale and controllable synthesis of metal-free carbon nanofibers and carbon nanotubes over water-soluble Na2CO3. Mater Lett 2012, 81: 135–137.View ArticleGoogle Scholar
- Qi XS, Zhong W, Yao XJ, Zhang H, Ding Q, Wu Q, Deng Y, Au C, Du Y: Controllable and large-scale synthesis of metal-free carbon nanofibers and carbon nanocoils over water-soluble NaxKy, catalysts. Carbon 2012, 50: 646–658. 10.1016/j.carbon.2011.08.076View ArticleGoogle Scholar
- Qi X, Ding Q, Zhong W, Au C-T, Du Y: Controllable synthesis and purification of carbon nanofibers and nanocoils over water-soluble NaNO3. Carbon 2013, 56: 383–385.View ArticleGoogle Scholar
- Glerup M, Castignolles M, Holzinger M, Hug G, Loiseau A, Bernier P: Synthesis of highly nitrogen-doped multi-walled carbon nanotubes. Chem Commun 2003, 2003: 2542–2543.View ArticleGoogle Scholar
- He MS, Zhou S, Zhang J, Liu ZF, Robinson C: CVD growth of N-doped carbon nanotubes on silicon substrates and its mechanism. J Phys Chem B 2005, 109: 9275–9279. 10.1021/jp044868dView ArticleGoogle Scholar
- Murakami Y, Miyauchi Y, Chiashi S, Maruyama S: Characterization of single-walled carbon nanotubes catalytically synthesized from alcohol. Chem Phys Lett 2003, 374: 53–58. 10.1016/S0009-2614(03)00687-0View ArticleGoogle Scholar
- Chen CM, Dai YM, Huang JG, Jehng JM: Intermetallic catalyst for carbon nanotubes (CNTs) growth by thermal chemical vapor deposition method. Carbon 2006, 44: 1808–1820. 10.1016/j.carbon.2005.12.043View ArticleGoogle Scholar
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