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Templated synthesis of metal nanotubes via electroless deposition
Materials Letters 61 (2007) 2641 – 2643 www.elsevier.com/locate/matlet
Templated synthesis of metal nanotubes via electroless deposition Guangwen Xie ⁎, Zhaobo Wang, Guicun Li, Yulong Shi, Zuolin Cui 1 , Zhikun Zhang Key Laboratory of Nanomaterials, Qingdao University of Science and Technology, No. 53 Zhengzhou Road, Qingdao 266042, P.R. China Received 13 July 2006; accepted 9 October 2006 Available online 25 October 2006
Abstract A simple route that utilizes carbon nanofibers as templates for preparing metal or alloy nanotubes via electroless deposition is developed. SEM and TEM images of the prepared Ni–Ni3P nanotubes are presented. In this method, it is easy to control the size or the shape of the prepared metal nanotubes by using different carbon or other nanofibers as templates. © 2006 Elsevier B.V. All rights reserved. Keywords: Templated synthesis; Ni–Ni3P nanotube; Electroless deposition
1. Introduction
2. Experimental
Recently much attention is focused on nanosized tubular materials in view of their unique structure, properties and potential applications as reservoirs in catalysis, fuel cells, sensors, and separation systems [1–5]. Since the discovery of carbon nanotubes [6], there have been a lot of reports on a variety of non-metal nanotubes [7–14]. For metals play an important role in catalysis and other nanotechnological fields, synthesis by using nanoporous polymer and anodic aluminum film as templates led to gold, nickel and palladium nanotubes [15–17], and platinum, palladium, silver nanotubes have been fabricated by using a surfactant or other molecular templates [18]. However, previous methods of preparing metal nanotubes are either complicated or difficult in controlling the size or the shape of the obtained metal nanotubes. In contrast, our recent study revealed that it is much more effective to use carbon or other nanofibers as templates for preparing metal or alloy nanotubes via electroless deposition.
The carbon nanofibers used as templates in this study were synthesized by a low temperature (300 °C) nano-copper catalytic CVD method. In this method, carbon source gas (such as acetylene) was introduced into a tube reactor which was heated to 300 °C from the outside and in the center of whichthe nano-copper catalyst particles were placed, the catalytic polymerization of acetylene took place on the surface of the catalyst particles and coiled carbon fibers were obtained [19,20]. The starting carbon nanofibers were washed in anhydrous ethanol and the mixture of butanol and xylene then were subjected to an oxidation treatment in the mixture of nitric acid and vitriolic acid to modify the surface chemistry and improve dispersion in the electroless bathe. These pretreated carbon nanofibers were suspended in a solution of sodium dodecyl sulfate (SDS) surfactant (1.0 wt.%) distilled water with stirring for 1 h, then sensitized in 0.1 M SnCl2 solution and activated in 0.01 M PdCl2 solution before electroless deposition. Ultrasonic agitation used in sensing and activating treatment was necessary to produce continuous coatings on the carbon nanofibers [21]. The electroless deposition of Ni–P alloy was performed in an acid solution, containing 25 g L− 1 nickel sulfate, 25 g L− 1 sodium hypophosphite as reducing agent, 12 g L− 1 sodium acetate and 30 mL L− 1 lactic acid as stabilizer. The pH value of the electroless solution was 5, which could be easily controlled
⁎ Corresponding author. Fax: +86 532 8402 2814. E-mail addresses: [email protected] (G. Xie), [email protected] (Z. Cui). 1 Fax: +86 532 8402 2869. 0167-577X/$ - see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2006.10.012
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G. Xie et al. / Materials Letters 61 (2007) 2641–2643
by the addition of ammonia solution. The process was optimized at 76 °C and the thickness of the coating could be controlled by the deposition time. The Ni–P coated carbon nanofibers were heated in air at 450 °C for 3 h to remove the templates, then heated in hydrogen at 400 °C for 2 h to reduce the metal oxide produced in the previous step, and the resulting products were obtained. The resulting products were characterized by FE-SEM (model JEOL-6700F), TEM (model JEM-2000EX) and EDX (energy dispersive X-ray microanalysis system). 3. Results and discussion Fig. 1a presents the scanning electron-microscope (SEM) image of the carbon nanofiber templates. These helical or straight templates have
diameters in the range of 100–200 nm. Fig. 1b gives the SEM image of the coated carbon nanofibers. It can be seen that the coatings are continuous and uniform. The thickness of the coatings is about 25 nm. Fig. 1c shows the SEM image of the products after removing the templates. From Fig. 1d, it is clear that the products possess hollow structures. Fig. 1e shows that some of the products can be helical, depending on the shape of the templates used. The transmission electron-microscope (TEM) image of the resulting products also shows the hollow structure (Fig. 2). From the SEM and TEM images, it can be seen that the prepared nanotubes have inner diameters of 100–200 nm, depending on the diameter of the templates, and outer diameters of 150–250 nm, depending on electroless deposition time. Helical or coiled nanotubes can be synthesized by using helical or coiled templates. The X-ray-diffraction (XRD) pattern shown in Fig. 3 indicates that the resulting products can be identified as the alloy of Ni (JCPDS, No 70-1849) and Ni3P (JCPDS, No 89-4748).
Fig. 1. SEM images of products. (a) Carbon nanofiber templates, (b) the Ni–P coated templates, (c) the Ni–Ni3P alloy nanotubes, (d) a magnified image from box 1 in (c), and (e) a magnified image of helical Ni–Ni3P alloy nanotube from box 2 in (c).
G. Xie et al. / Materials Letters 61 (2007) 2641–2643
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Fig. 4. The EDX spectra of the Ni–Ni3P alloy nanotubes.
gold, platinum, palladium, and various alloy nanotubes can also be synthesized by using this method. Acknowledgments
Fig. 2. TEM images of Ni–Ni3P alloy nanotubes.
The chemical composition of the Ni–Ni3P alloy nanotubes was determined by EDX (Fig. 4) and 91.7% (wt.%) nickel, and 8.3% (wt.%) phosphorus could be detected. The EDX was calibrated by using pure nickel (99.99%) sample. It is expected that many other metal or alloy nanotubes can also be synthesized with this method by adjusting the composition of electroless bath and using different nanofibers as templates.
Financial supports from the Education Bureau of Shandong Province (J04B13) and the Natural Science Foundation of Shandong Province are greatly appreciated. References [1] [2] [3] [4] [5]
4. Conclusion
[6] [7]
Metal or alloy nanotubes can be synthesized by using carbon or other nanofibers as templates via electroless deposition. The inner diameter of the synthesized Ni–P alloy nanotubes can be easily controlled by using different sized templates, the outer diameter of the nanotubes can be controlled by the electroless deposition rate or deposition time, and the shape of the obtained nanotubes can also be controlled by the templates used. Moreover, other metal nanotubes such as silver, copper, cobalt,
[8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21]
Fig. 3. XRD pattern of Ni–Ni3P alloy nanotubes.
R. Coontz, P. Szuromi, Science 290 (2000) 1523. Y. Sun, B. Mayers, Y. Xia, Adv. Mater. 15 (2003) 641. C.J. Brumlik, V.P. Menon, C.R. Mrtin, J. Mater. Res. 9 (1994) 1174. W. Tremel, Angew. Chem. 111 (1999) 2311; Angew. Chem., Int. Ed. Engl. 38 (1999) 2175. K.J.C. van Bommel, A. Friggeri, S. Shinkai, Angew. Chem., Int. Ed. Engl. 42 (2003) 980. S. Iijima, Nature 354 (1991) 56. N.G. Chopra, R.J. Ruyken, K. Cherry, V.H. Crespi, M.L. Cohen, S.G. Louie, A. Zettl, Science 269 (1995) 966. R. Tenne, L. Margulis, M. Genut, G. Hodes, Nature 360 (1992) 444. Y. Feldman, E. Wasserman, D.J. Srolovitz, R. Tenne, Science 267 (1995) 222. R. Ma, Y. Bando, D. Golberg, T. Sato, Angew. Chem., Int. Ed. Engl. 42 (2003) 1836. M.E. Spahr, P. Bitterli, R. Nesper, M. Müller, F. Krumeich, H.U. Nissen, Angew. Chem., Int. Ed. Engl. 37 (1998) 1263. C.N.R. Rao, B.C. Satishkumar, A. Govindaraj, Chem. Commun. (1997) 1581. H.-P. Lin, C.-Y. Mou, S.-B. Liu, Adv. Mater. 12 (2000) 103. M. Yada, M. Mihara, S. Mouri, M. Kuroki, T. Kijima, Adv. Mater. 14 (2002) 309. C.R. Martin, Science 266 (1994) 1961. J. Bao, C. Tie, Z. Xu, O. Ma, D. Sheng, Adv. Mater. 14 (2002) 44. M. Steinhart, Z. Jia, A.K. Schaper, R.B. Wehrspohn, U. Gosele, J.H. Wendorff, Adv. Mater. 15 (2003) 706. T. Kijima, T. Yoshimura, M. Uota, T. Ikeda, D. Fujikawa, S. Mouri, S. Uoyama, Angew. Chem., Int. Ed. Engl. 43 (2004) 228. Y. Qin, Z.K. Zhang, Z.L. Cui, Carbon 41 (2003) 3072. Y. Qin, Q. Zhang, Z.L. Cui, J. Catal. 223 (2004) 389. G.W. Xie, Z.B. Wang, Z.L. Cui, Y.L. Shi, Carbon 43 (2005) 3181.
Templated synthesis of metal nanotubes via electroless deposition Guangwen Xie ⁎, Zhaobo Wang, Guicun Li, Yulong Shi, Zuolin Cui 1 , Zhikun Zhang Key Laboratory of Nanomaterials, Qingdao University of Science and Technology, No. 53 Zhengzhou Road, Qingdao 266042, P.R. China Received 13 July 2006; accepted 9 October 2006 Available online 25 October 2006
Abstract A simple route that utilizes carbon nanofibers as templates for preparing metal or alloy nanotubes via electroless deposition is developed. SEM and TEM images of the prepared Ni–Ni3P nanotubes are presented. In this method, it is easy to control the size or the shape of the prepared metal nanotubes by using different carbon or other nanofibers as templates. © 2006 Elsevier B.V. All rights reserved. Keywords: Templated synthesis; Ni–Ni3P nanotube; Electroless deposition
1. Introduction
2. Experimental
Recently much attention is focused on nanosized tubular materials in view of their unique structure, properties and potential applications as reservoirs in catalysis, fuel cells, sensors, and separation systems [1–5]. Since the discovery of carbon nanotubes [6], there have been a lot of reports on a variety of non-metal nanotubes [7–14]. For metals play an important role in catalysis and other nanotechnological fields, synthesis by using nanoporous polymer and anodic aluminum film as templates led to gold, nickel and palladium nanotubes [15–17], and platinum, palladium, silver nanotubes have been fabricated by using a surfactant or other molecular templates [18]. However, previous methods of preparing metal nanotubes are either complicated or difficult in controlling the size or the shape of the obtained metal nanotubes. In contrast, our recent study revealed that it is much more effective to use carbon or other nanofibers as templates for preparing metal or alloy nanotubes via electroless deposition.
The carbon nanofibers used as templates in this study were synthesized by a low temperature (300 °C) nano-copper catalytic CVD method. In this method, carbon source gas (such as acetylene) was introduced into a tube reactor which was heated to 300 °C from the outside and in the center of whichthe nano-copper catalyst particles were placed, the catalytic polymerization of acetylene took place on the surface of the catalyst particles and coiled carbon fibers were obtained [19,20]. The starting carbon nanofibers were washed in anhydrous ethanol and the mixture of butanol and xylene then were subjected to an oxidation treatment in the mixture of nitric acid and vitriolic acid to modify the surface chemistry and improve dispersion in the electroless bathe. These pretreated carbon nanofibers were suspended in a solution of sodium dodecyl sulfate (SDS) surfactant (1.0 wt.%) distilled water with stirring for 1 h, then sensitized in 0.1 M SnCl2 solution and activated in 0.01 M PdCl2 solution before electroless deposition. Ultrasonic agitation used in sensing and activating treatment was necessary to produce continuous coatings on the carbon nanofibers [21]. The electroless deposition of Ni–P alloy was performed in an acid solution, containing 25 g L− 1 nickel sulfate, 25 g L− 1 sodium hypophosphite as reducing agent, 12 g L− 1 sodium acetate and 30 mL L− 1 lactic acid as stabilizer. The pH value of the electroless solution was 5, which could be easily controlled
⁎ Corresponding author. Fax: +86 532 8402 2814. E-mail addresses: [email protected] (G. Xie), [email protected] (Z. Cui). 1 Fax: +86 532 8402 2869. 0167-577X/$ - see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2006.10.012
2642
G. Xie et al. / Materials Letters 61 (2007) 2641–2643
by the addition of ammonia solution. The process was optimized at 76 °C and the thickness of the coating could be controlled by the deposition time. The Ni–P coated carbon nanofibers were heated in air at 450 °C for 3 h to remove the templates, then heated in hydrogen at 400 °C for 2 h to reduce the metal oxide produced in the previous step, and the resulting products were obtained. The resulting products were characterized by FE-SEM (model JEOL-6700F), TEM (model JEM-2000EX) and EDX (energy dispersive X-ray microanalysis system). 3. Results and discussion Fig. 1a presents the scanning electron-microscope (SEM) image of the carbon nanofiber templates. These helical or straight templates have
diameters in the range of 100–200 nm. Fig. 1b gives the SEM image of the coated carbon nanofibers. It can be seen that the coatings are continuous and uniform. The thickness of the coatings is about 25 nm. Fig. 1c shows the SEM image of the products after removing the templates. From Fig. 1d, it is clear that the products possess hollow structures. Fig. 1e shows that some of the products can be helical, depending on the shape of the templates used. The transmission electron-microscope (TEM) image of the resulting products also shows the hollow structure (Fig. 2). From the SEM and TEM images, it can be seen that the prepared nanotubes have inner diameters of 100–200 nm, depending on the diameter of the templates, and outer diameters of 150–250 nm, depending on electroless deposition time. Helical or coiled nanotubes can be synthesized by using helical or coiled templates. The X-ray-diffraction (XRD) pattern shown in Fig. 3 indicates that the resulting products can be identified as the alloy of Ni (JCPDS, No 70-1849) and Ni3P (JCPDS, No 89-4748).
Fig. 1. SEM images of products. (a) Carbon nanofiber templates, (b) the Ni–P coated templates, (c) the Ni–Ni3P alloy nanotubes, (d) a magnified image from box 1 in (c), and (e) a magnified image of helical Ni–Ni3P alloy nanotube from box 2 in (c).
G. Xie et al. / Materials Letters 61 (2007) 2641–2643
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Fig. 4. The EDX spectra of the Ni–Ni3P alloy nanotubes.
gold, platinum, palladium, and various alloy nanotubes can also be synthesized by using this method. Acknowledgments
Fig. 2. TEM images of Ni–Ni3P alloy nanotubes.
The chemical composition of the Ni–Ni3P alloy nanotubes was determined by EDX (Fig. 4) and 91.7% (wt.%) nickel, and 8.3% (wt.%) phosphorus could be detected. The EDX was calibrated by using pure nickel (99.99%) sample. It is expected that many other metal or alloy nanotubes can also be synthesized with this method by adjusting the composition of electroless bath and using different nanofibers as templates.
Financial supports from the Education Bureau of Shandong Province (J04B13) and the Natural Science Foundation of Shandong Province are greatly appreciated. References [1] [2] [3] [4] [5]
4. Conclusion
[6] [7]
Metal or alloy nanotubes can be synthesized by using carbon or other nanofibers as templates via electroless deposition. The inner diameter of the synthesized Ni–P alloy nanotubes can be easily controlled by using different sized templates, the outer diameter of the nanotubes can be controlled by the electroless deposition rate or deposition time, and the shape of the obtained nanotubes can also be controlled by the templates used. Moreover, other metal nanotubes such as silver, copper, cobalt,
[8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21]
Fig. 3. XRD pattern of Ni–Ni3P alloy nanotubes.
R. Coontz, P. Szuromi, Science 290 (2000) 1523. Y. Sun, B. Mayers, Y. Xia, Adv. Mater. 15 (2003) 641. C.J. Brumlik, V.P. Menon, C.R. Mrtin, J. Mater. Res. 9 (1994) 1174. W. Tremel, Angew. Chem. 111 (1999) 2311; Angew. Chem., Int. Ed. Engl. 38 (1999) 2175. K.J.C. van Bommel, A. Friggeri, S. Shinkai, Angew. Chem., Int. Ed. Engl. 42 (2003) 980. S. Iijima, Nature 354 (1991) 56. N.G. Chopra, R.J. Ruyken, K. Cherry, V.H. Crespi, M.L. Cohen, S.G. Louie, A. Zettl, Science 269 (1995) 966. R. Tenne, L. Margulis, M. Genut, G. Hodes, Nature 360 (1992) 444. Y. Feldman, E. Wasserman, D.J. Srolovitz, R. Tenne, Science 267 (1995) 222. R. Ma, Y. Bando, D. Golberg, T. Sato, Angew. Chem., Int. Ed. Engl. 42 (2003) 1836. M.E. Spahr, P. Bitterli, R. Nesper, M. Müller, F. Krumeich, H.U. Nissen, Angew. Chem., Int. Ed. Engl. 37 (1998) 1263. C.N.R. Rao, B.C. Satishkumar, A. Govindaraj, Chem. Commun. (1997) 1581. H.-P. Lin, C.-Y. Mou, S.-B. Liu, Adv. Mater. 12 (2000) 103. M. Yada, M. Mihara, S. Mouri, M. Kuroki, T. Kijima, Adv. Mater. 14 (2002) 309. C.R. Martin, Science 266 (1994) 1961. J. Bao, C. Tie, Z. Xu, O. Ma, D. Sheng, Adv. Mater. 14 (2002) 44. M. Steinhart, Z. Jia, A.K. Schaper, R.B. Wehrspohn, U. Gosele, J.H. Wendorff, Adv. Mater. 15 (2003) 706. T. Kijima, T. Yoshimura, M. Uota, T. Ikeda, D. Fujikawa, S. Mouri, S. Uoyama, Angew. Chem., Int. Ed. Engl. 43 (2004) 228. Y. Qin, Z.K. Zhang, Z.L. Cui, Carbon 41 (2003) 3072. Y. Qin, Q. Zhang, Z.L. Cui, J. Catal. 223 (2004) 389. G.W. Xie, Z.B. Wang, Z.L. Cui, Y.L. Shi, Carbon 43 (2005) 3181.