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Template-free synthesis of nickel nanowires by magnetic field
Materials Letters 63 (2009) 1650–1652
Contents lists available at ScienceDirect
Materials Letters j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / m a t l e t
Template-free synthesis of nickel nanowires by magnetic field Ping Liu, Zijiong Li, Bo Zhao, Boluo Yadian, Yafei Zhang ⁎ National Key Laboratory of Nano/Micro Fabrication Technology, Key Laboratory for Thin Film and Microfabrication of the Ministry of Education, Institute of Micro/Nano Science and Technology, Shanghai Jiao Tong University, Shanghai 200240, PR China
a r t i c l e
i n f o
Article history: Received 1 December 2008 Accepted 23 April 2009 Available online 3 May 2009 Keywords: Nanomaterials Magnetic materials Nickel nanowires Magnetic field
a b s t r a c t Nickel nanowires were prepared by a template free method combined with chemical reduction and magnetic field. The application of an external magnetic field resulted in the formation of self-aligned metallic nickel nanowires of about 50 nm in diameter. Nickel particles were prepared in the absence of a magnetic field to better illustrate the structure directing role of the magnetic field. Physical properties of the nickel nanochains were examined by scanning electron microscopy (SEM), transmission electron microscope (TEM), X-Ray diffraction (XRD), and thermogravimetric analysis (TGA) methods. This study provides a simple method to prepare Ni nanowires in large scale which broads their practical applications. © 2009 Elsevier B.V. All rights reserved.
1. Introduction
2. Experimental
In recent years, nanostructure materials have been actively studied due to both scientific interests and potential applications [1]. Among them, much attention has been focused on the research field of onedimensional nanostructure materials, such as nanorods, nanowires, nanofibres, or nanochains, because of their potential applications in nanodevices [2–4]. Ni nanowires with uniform shape and high purity is increasingly required for specific uses in many technological areas, especially on the preparation of magnetic materials, microwave absorbing materials, magnetic recording media, commercial batteries and the formation of catalysts [5,6]. C.Y. Yu, et al. prepared Ni nanowire arrays by the deposition of Ni into the alumina template with nanopores [7]. Chen-Min Liu, et al. synthesized Ni nanochains with diameters of 150– 250 nm and lengths of 0.5–2 μm by assembly of small nanoparticles [4]. Haijun Zhang, et al. prepared Ni hollow fiber by electroless plating using a kind of natural silk as template [8]. However, they all used templates to fabricate nickel nanostructure materials. The complex and often multi-step preparation of the template and the required complete residue free separation from the nanowires after production have motivated investigations into template free method [9]. In this paper, a template free method by combining chemical reduction and magnetic field is applied to prepare Ni nanowires. The properties of fabricated Ni nanowires are investigated. Nickel particles were prepared in the absence of a magnetic field to better illustrate the structure directing role of the magnetic field. The present study provides a simple method to prepare Ni nanowires in large scale which broads their practical applications.
Solution of nickel ion was prepared by dissolving an analytical grade NiCl2·6H2O in the mixture solution of deionized water and ethanol (Vdeionized water/Vethanol = 5:4). [Ni2+] is 0.0062 M. The pH value of the solution was adjusted by 5 M NaOH solution to 13.7. Hydrazine hydrate was added as reducing agent. The volume ration of N2H4·H2O to ethanol is 8:15. The mixture was heated to 50 °C and kept at 50 °C for 30 min under magnetic field. The magnetic field intensity is 0.515 T. The nickel samples were separated from the solution and washed with deionized water. The Ni samples were finally dried in vacuum oven at 60 °C for 12 h. The surface morphology and inner microstructure of the sample were studied by field-emission-scanning electron microscopy (FE-SEM, FEI SIRION 200, USA) and transmission electron microscope (TEM, JEOL, JEM-100CX). Thermogravimetric analyzer (TGA) of prepared Ni samples were carried out on a pyris 1 TGA (Perkin Elmer) Thermal Analysis System with a rising temperature rate 10 °C/min in flowing air. X-ray diffraction pattern was recorded from 20° to 80°, using D8 ADVANCE X-ray polycrystaline diffractometer (Bruker).
⁎ Corresponding author. E-mail address: [email protected] (Y. Zhang). 0167-577X/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2009.04.031
3. Results and discussions The surface morphology of nickel nanowires is shown in Fig. 1. The linear nanowires consist of single nearly spherical nanoparticles with an average particle size of 50 nm. Fig. 2 shows that nickel nanoparticles are assembled to wellproportioned solid linear structure in the magnetic field. Additionally, the fact that nickel nanowires retain their linear structure after ultrasonic treatment for 30 min proves that the nanowires possess a certain degree of mechanical strength.
P. Liu et al. / Materials Letters 63 (2009) 1650–1652
1651
Fig. 1. SEM photograph of Ni nanowires prepared by template free method.
In order to better illustrate the structure directing role of the magnetic field, nickel particles were prepared in the absence of a magnetic field. The spherical nickel particles can be distinguished in Fig. 3. The diameter of nickel particles is about 700 nm. Nickel nanoparticles aggregated larger spherical particles rather than nickel nanowires in the absence of a magnetic field. Fig. 4 shows the X-ray diffraction pattern of Ni sample. The diffraction peaks near the diffraction angles of 45°, 52°, 76° correspond to the diffractions of crystal face (111), (200), and (220) respectively. It is consistent with standard diffraction data of nickel which confirms that the sample consists of nickel. From the XRD spectra, it could be
Fig. 4. XRD spectra of Ni nanochains prepared by template free method.
Fig. 5. Thermogravimetric analysis of nickel nanochains prepared by template free method.
seen that there are some weak peaks for Ni(OH)2 which means there is a small quantity of Ni(OH)2 in the sample. Nickel was obtained by following reactions: Fig. 2. TEM image of Ni nanowires prepared by template free method.
Ni
2þ
þ 2OHˉ→NiðOHÞ2 ↓
2NiðOHÞ2 þ N2 H4 ¼ 2Ni↓ þ N2 ↑ þ 4H2 O
ð1Þ ð2Þ
The occurrence of Ni(OH)2 means the quantity of N2H4 is not enough to deoxidize all of Ni(OH)2. The Ni(OH)2 could be eliminated by adding more N2H4. In order to understand the stability of the prepared Ni nanowires in air, they were characterized by using Thermogravimetric analyzer (TGA). As shown in Fig. 5, the pure nickel nanochains began to be oxidized around 350 °C, the final weight gain is about 11.5% that are difference with the theoretical weight gain (27.3%) for perfect conversion of pure Ni to NiO. This datum indicates that the oxidation process from Ni to NiO is not complete yet at about 800 °C. Between 320 °C and 350 °C, there is a little weight loss which is caused by the reaction of Ni(OH)2. The reaction is
Fig. 3. SEM photograph of Ni nanowires prepared in the absence of a magnetic field.
NiðOHÞ2 →NiO þ H2 O:
ð3Þ
1652
P. Liu et al. / Materials Letters 63 (2009) 1650–1652
Conclusions Nickel nanowires were successfully prepared by a template free method combined chemical reduction and magnetic field. The application of an external magnetic field resulted in the formation of self-aligned metallic nickel nanowires of about 50 nm diameter. The nickel nanowires possess a certain degree of mechanical strength. Nickel nanoparticles aggregated larger spherical particles rather than nickel nanowires in the absence of a magnetic field. The nickel sample contains a small quantity of Ni(OH)2 which could be eliminated by adding more N2H4. Nickel nanowires are stable in air when the temperate is lower than 320 °C. The present study provides a simple method to prepare Ni nanowires in large scale which broads their practical applications.
Research and Development fund No.07SA10, National Natural Science Foundation of China No.50730008, Shanghai Science and Technology Grant No:0752nm015 and National Basic Research Program of China No.2006CB300406.
References [1] [2] [3] [4] [5] [6] [7] [8]
Acknowledgements [9]
This work is supported by Hi-Tech Research and Development Program of China No. 2007AA03Z300, Shanghai-Applied Materials
Ball P, Garwin L. Nature 1992;355:761–6. Hu J, Ouyang M, Yang P, Lieber CM. Nature 1999;399:48–51. Xu DS, Guo GL, Gui LL, Tang YQ, Shi EJ, Jin EX, et al. Appl Phys Lett 1999;75:481–3. Liu Chen-Min, Guo Lin, Wang Rong-Ming, Deng Yuan, Xua Hui-Bin, Yang Shihe. Chem Commun 2004:2726–27267. Vassal N, Salmon E, Fauvarque J. J Electrochem Soc 1999;146:20–6. Laughlin D, Lu B, Hsu Y, Zou J, Lambeth D. IEEE Trans Magn 2000;36:48–53. Yu CY, Yu YL, Sun HY, Xu T, Li XH, Li W, et al. Mater Lett 2007;61:1859–62. Zhang Haijun, Liu Yun. Preparation and microwave properties of Ni hollow fiber by electroless plating-template method. J Alloys Compd June 30 2008;458(1– 2):588–94. Athanassiou EA, Grossmann P, Grass RN, Stark WJ. Template free, large scale synthesis of cobalt nanowires using magnetic fields for alignment. Nanotechnology 2007;18:165606.
Contents lists available at ScienceDirect
Materials Letters j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / m a t l e t
Template-free synthesis of nickel nanowires by magnetic field Ping Liu, Zijiong Li, Bo Zhao, Boluo Yadian, Yafei Zhang ⁎ National Key Laboratory of Nano/Micro Fabrication Technology, Key Laboratory for Thin Film and Microfabrication of the Ministry of Education, Institute of Micro/Nano Science and Technology, Shanghai Jiao Tong University, Shanghai 200240, PR China
a r t i c l e
i n f o
Article history: Received 1 December 2008 Accepted 23 April 2009 Available online 3 May 2009 Keywords: Nanomaterials Magnetic materials Nickel nanowires Magnetic field
a b s t r a c t Nickel nanowires were prepared by a template free method combined with chemical reduction and magnetic field. The application of an external magnetic field resulted in the formation of self-aligned metallic nickel nanowires of about 50 nm in diameter. Nickel particles were prepared in the absence of a magnetic field to better illustrate the structure directing role of the magnetic field. Physical properties of the nickel nanochains were examined by scanning electron microscopy (SEM), transmission electron microscope (TEM), X-Ray diffraction (XRD), and thermogravimetric analysis (TGA) methods. This study provides a simple method to prepare Ni nanowires in large scale which broads their practical applications. © 2009 Elsevier B.V. All rights reserved.
1. Introduction
2. Experimental
In recent years, nanostructure materials have been actively studied due to both scientific interests and potential applications [1]. Among them, much attention has been focused on the research field of onedimensional nanostructure materials, such as nanorods, nanowires, nanofibres, or nanochains, because of their potential applications in nanodevices [2–4]. Ni nanowires with uniform shape and high purity is increasingly required for specific uses in many technological areas, especially on the preparation of magnetic materials, microwave absorbing materials, magnetic recording media, commercial batteries and the formation of catalysts [5,6]. C.Y. Yu, et al. prepared Ni nanowire arrays by the deposition of Ni into the alumina template with nanopores [7]. Chen-Min Liu, et al. synthesized Ni nanochains with diameters of 150– 250 nm and lengths of 0.5–2 μm by assembly of small nanoparticles [4]. Haijun Zhang, et al. prepared Ni hollow fiber by electroless plating using a kind of natural silk as template [8]. However, they all used templates to fabricate nickel nanostructure materials. The complex and often multi-step preparation of the template and the required complete residue free separation from the nanowires after production have motivated investigations into template free method [9]. In this paper, a template free method by combining chemical reduction and magnetic field is applied to prepare Ni nanowires. The properties of fabricated Ni nanowires are investigated. Nickel particles were prepared in the absence of a magnetic field to better illustrate the structure directing role of the magnetic field. The present study provides a simple method to prepare Ni nanowires in large scale which broads their practical applications.
Solution of nickel ion was prepared by dissolving an analytical grade NiCl2·6H2O in the mixture solution of deionized water and ethanol (Vdeionized water/Vethanol = 5:4). [Ni2+] is 0.0062 M. The pH value of the solution was adjusted by 5 M NaOH solution to 13.7. Hydrazine hydrate was added as reducing agent. The volume ration of N2H4·H2O to ethanol is 8:15. The mixture was heated to 50 °C and kept at 50 °C for 30 min under magnetic field. The magnetic field intensity is 0.515 T. The nickel samples were separated from the solution and washed with deionized water. The Ni samples were finally dried in vacuum oven at 60 °C for 12 h. The surface morphology and inner microstructure of the sample were studied by field-emission-scanning electron microscopy (FE-SEM, FEI SIRION 200, USA) and transmission electron microscope (TEM, JEOL, JEM-100CX). Thermogravimetric analyzer (TGA) of prepared Ni samples were carried out on a pyris 1 TGA (Perkin Elmer) Thermal Analysis System with a rising temperature rate 10 °C/min in flowing air. X-ray diffraction pattern was recorded from 20° to 80°, using D8 ADVANCE X-ray polycrystaline diffractometer (Bruker).
⁎ Corresponding author. E-mail address: [email protected] (Y. Zhang). 0167-577X/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2009.04.031
3. Results and discussions The surface morphology of nickel nanowires is shown in Fig. 1. The linear nanowires consist of single nearly spherical nanoparticles with an average particle size of 50 nm. Fig. 2 shows that nickel nanoparticles are assembled to wellproportioned solid linear structure in the magnetic field. Additionally, the fact that nickel nanowires retain their linear structure after ultrasonic treatment for 30 min proves that the nanowires possess a certain degree of mechanical strength.
P. Liu et al. / Materials Letters 63 (2009) 1650–1652
1651
Fig. 1. SEM photograph of Ni nanowires prepared by template free method.
In order to better illustrate the structure directing role of the magnetic field, nickel particles were prepared in the absence of a magnetic field. The spherical nickel particles can be distinguished in Fig. 3. The diameter of nickel particles is about 700 nm. Nickel nanoparticles aggregated larger spherical particles rather than nickel nanowires in the absence of a magnetic field. Fig. 4 shows the X-ray diffraction pattern of Ni sample. The diffraction peaks near the diffraction angles of 45°, 52°, 76° correspond to the diffractions of crystal face (111), (200), and (220) respectively. It is consistent with standard diffraction data of nickel which confirms that the sample consists of nickel. From the XRD spectra, it could be
Fig. 4. XRD spectra of Ni nanochains prepared by template free method.
Fig. 5. Thermogravimetric analysis of nickel nanochains prepared by template free method.
seen that there are some weak peaks for Ni(OH)2 which means there is a small quantity of Ni(OH)2 in the sample. Nickel was obtained by following reactions: Fig. 2. TEM image of Ni nanowires prepared by template free method.
Ni
2þ
þ 2OHˉ→NiðOHÞ2 ↓
2NiðOHÞ2 þ N2 H4 ¼ 2Ni↓ þ N2 ↑ þ 4H2 O
ð1Þ ð2Þ
The occurrence of Ni(OH)2 means the quantity of N2H4 is not enough to deoxidize all of Ni(OH)2. The Ni(OH)2 could be eliminated by adding more N2H4. In order to understand the stability of the prepared Ni nanowires in air, they were characterized by using Thermogravimetric analyzer (TGA). As shown in Fig. 5, the pure nickel nanochains began to be oxidized around 350 °C, the final weight gain is about 11.5% that are difference with the theoretical weight gain (27.3%) for perfect conversion of pure Ni to NiO. This datum indicates that the oxidation process from Ni to NiO is not complete yet at about 800 °C. Between 320 °C and 350 °C, there is a little weight loss which is caused by the reaction of Ni(OH)2. The reaction is
Fig. 3. SEM photograph of Ni nanowires prepared in the absence of a magnetic field.
NiðOHÞ2 →NiO þ H2 O:
ð3Þ
1652
P. Liu et al. / Materials Letters 63 (2009) 1650–1652
Conclusions Nickel nanowires were successfully prepared by a template free method combined chemical reduction and magnetic field. The application of an external magnetic field resulted in the formation of self-aligned metallic nickel nanowires of about 50 nm diameter. The nickel nanowires possess a certain degree of mechanical strength. Nickel nanoparticles aggregated larger spherical particles rather than nickel nanowires in the absence of a magnetic field. The nickel sample contains a small quantity of Ni(OH)2 which could be eliminated by adding more N2H4. Nickel nanowires are stable in air when the temperate is lower than 320 °C. The present study provides a simple method to prepare Ni nanowires in large scale which broads their practical applications.
Research and Development fund No.07SA10, National Natural Science Foundation of China No.50730008, Shanghai Science and Technology Grant No:0752nm015 and National Basic Research Program of China No.2006CB300406.
References [1] [2] [3] [4] [5] [6] [7] [8]
Acknowledgements [9]
This work is supported by Hi-Tech Research and Development Program of China No. 2007AA03Z300, Shanghai-Applied Materials
Ball P, Garwin L. Nature 1992;355:761–6. Hu J, Ouyang M, Yang P, Lieber CM. Nature 1999;399:48–51. Xu DS, Guo GL, Gui LL, Tang YQ, Shi EJ, Jin EX, et al. Appl Phys Lett 1999;75:481–3. Liu Chen-Min, Guo Lin, Wang Rong-Ming, Deng Yuan, Xua Hui-Bin, Yang Shihe. Chem Commun 2004:2726–27267. Vassal N, Salmon E, Fauvarque J. J Electrochem Soc 1999;146:20–6. Laughlin D, Lu B, Hsu Y, Zou J, Lambeth D. IEEE Trans Magn 2000;36:48–53. Yu CY, Yu YL, Sun HY, Xu T, Li XH, Li W, et al. Mater Lett 2007;61:1859–62. Zhang Haijun, Liu Yun. Preparation and microwave properties of Ni hollow fiber by electroless plating-template method. J Alloys Compd June 30 2008;458(1– 2):588–94. Athanassiou EA, Grossmann P, Grass RN, Stark WJ. Template free, large scale synthesis of cobalt nanowires using magnetic fields for alignment. Nanotechnology 2007;18:165606.