Journal of Nanomaterials

Journal of Nanomaterials / 2010 / Article

Research Article | Open Access

Volume 2010 |Article ID 403197 | 5 pages | https://doi.org/10.1155/2010/403197

Effects of Current on Arc Fabrication of Cu Nanoparticles

Academic Editor: Lian Gao
Received03 May 2009
Revised17 Aug 2009
Accepted08 Jan 2010
Published01 Apr 2010

Abstract

Arc-fabricated copper nanoparticles (Cu Nps) size, morphology and the crystalline structure, as well as the yields of Nps appear sensitive to the applied currents (50–160 A) in distilled water. The results indicate that the sizes of Cu Nps are directly proportional to the currents employed. At 50 A, TEM, XRD, and SEM analyses show fabrication of relatively purest, the most dispersed, face-centered cubic (fcc) brown Cu Nps with rather smallest average size of 20 nm. At the same current, the TGA-DTA analysis reveals neither weight loss nor gain, indicating thermal stability of the fabricated Cu Nps.

1. Introduction

There is a significant interest in the syntheses and applications of nanoparticles (Nps) [1]. Following the great implications of copper for its high electrical conductivity and catalytic properties, copper nanoparticles (Cu Nps) are now attracting great technological interests [24]. Many techniques are developed to prepare copper nanostructures, including ultrasonic-chemical [5], electrolysis [6], sol-gel [7], inverse microemulsion [8], chemical reduction [9], microwave irradiation [10], supercritical extraction [11], hydrothermal method [12], laser ablation [13], plasma [14], and submerged arc nanoparticle synthesis system (SANSS) [1521]. Among these methods, electric arc evaporation is the most efficient method for the direct fabrication of Cu Nps (one-pot synthesis) through formation of dense metal-vapor-clouds. The latter formed because of the high temperature and compactness of the electrode spots produced as the arc attachment points [14]. Formation of uniform CuO nanorods along with CuO, , and Cu Nps via a solid-liquid phase arc discharge process is reported [22]. Also, Cu Nps and Cu nanofluid fabrication through a pressure control technique called “arc-submerged nanoparticle synthesis system (ASNSS)” is reported by Tsung et al. [15, 16]. Consequently, they used SANSS to prepare CuO Nps dispersed uniformly in dielectric liquid [1721], and also they fabricated Ag, Ni, and using this method [2325]. We have also reported syntheses of the low-cost Cu Nps and Nps preparation through explosion of copper wires [26]. Water introduced as the medium of choice by many reports, including our recent account of media effects on arc fabrications of nanobrass (63%Cu + 37%Zn) [27]. While arc fabrication of Cu Nps in distilled water is already reported, the crucial role of current is not addressed yet. Hence, in this manuscript we adopt distilled water for probing the effects of current (50–160 A) on the arc fabrications of Cu Nps. It is found that density of current is a key factor for the morphology, controlling particle sizes, and yields of copper Nps. Increasing the current can cause to increasing the particle sizes and decreasing the yield of Nps production [28].

2. Experimental

Our arc method requires only a direct current (DC) power supply and commercially available copper rods. Two high-purity copper rods (95.90%) with diameters of 2.5 mm and length of 30 mm are employed as a movable anode and a static cathode in our arc discharge experiments in distilled water. The distance between the two copper electrodes is set at 1 mm with a angle between the two electrodes. Different currents (30, 50, 70, 90, 100, 115, 150, 160 amperes) are passed through water-submerged copper electrodes (1–10 milliseconds). The arc discharge is initiated by slowly detaching the moveable anode from the cathode. Consequently, the cathode-anode gap is controlled at approximately 1 mm to maintain a stable discharge current and average voltage of 25 V in experiments. Separating the electrodes increases the voltage, while bringing the electrodes close together decreases it. The voltages and currents employed are recorded when stable discharge conditions are attained.

The Cu electrodes are heated by the high temperature of the arc, and metal atoms are separated from the metal surface and evaporated into metal vapour. The cooled metal vapor in water lead to the formation of primary particles by nucleation mechanism turning into Cu Nps dispersed in distilled water [29]. Gas bubbles are formed in the water during the arc process due to the plasma vaporization/decomposition of the anode material and water. These escaping gas bubbles act both as a condensing media and as carriers of the final products to the water surface. The growth rate of the nucleus is controlled by the concentration of the vaporized metal and the temperature of the medium [30]. The X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) are used for depiction crystalline structure, morphology, and size of Cu Nps, respectively. Thermal stability of Cu Nps is characterized by thermogravimetric and differential thermal analyses (TGA-DTA).

3. Results and Discussion

Our objective in this work is to find the best current for fabrication Cu Nps with the better uniformity, good particle size distribution, and the higher yield. We discussed in detail the impact of current on the metal Nps fabrication elsewhere [28]. Eight different currents (30, 50, 70, 90, 100, 115, 150, and 160 A) are passed through Cu electrodes. At the employed currents 50 A, two distinct nanopowders (w/w ) are obtained which become easily separated through filtration. The major nanopowder is a brown precipitate which consists of pure Cu Nps, while the minor product is a black color, water-suspended mixture of Nps, consisting of copper oxide Nps (CuO and Nps).

3.1. SEM and XRD Analyses

SEM and XRD results indicate that the less miscible, arc-fabricated, brown powders are made of pure Cu Nps, which appear as face-centered cubic (fcc) crystals (Figures 1(a)1(g) and 2). These SEM images are in contrast to those of the starting copper electrodes, which indicate no evidence of nanostructure, prior to the arc discharge (Figure 1(h)). The visual inspection of the SEM images shows conspicuous current effects on the yield, size, and morphology of brown Cu Nps (Figure 1). Accordingly, in the distilled water, 50 A is rather the best current which produce the size-selected, single crystalline Cu Nps with the average size of 58 nm (Figure 1(a), see (S), Figure  S1in Supplementary Material available online at doi: 10.1155/2010/403197).

SEM results show that increasing the current enlarges mean-sizes of the Cu Nps (Figure  S1). Obviously, the higher arc currents increase the rate of anodic erosion, causing an increase in the macroparticle formations [14]. At currents higher than 100 A, the yield of Nps drops while their sizes increase (Figures 1(e)1(g), Figure  ). This is due to the higher rate of vaporization of copper atoms at higher currents, making the growth rate of particles higher leading to larger particle size [31]. As a result, the sizes of Cu Nps are directly proportional to the currents employed (Figure 3). While changing current has significant effects on the particle size, it does not show any noticeable impact on the Cu Nps compositions. Hence, brown Cu Nps, formed in distilled water, at different currents, show XRD lines (111), (200), and (220) at , respectively, (Figure 2).

In other words, at all currents positions and intensities of XRD peaks are similar, suggesting arc fabrications of pure Cu Nps. At all the employed currents, a watery black nanopowder is produced as a byproduct (w/w 1  :  50), in addition to the arc fabricated brown Cu Nps (Figure  S2). The XRD patterns of the brown Cu Nps, fabricated at different currents, do not change after one-month storages in the open air, or distilled water. In contrast, one month storages of the “black nanopowders”, in distilled water, induce changes in their XRD patterns, reflecting further oxidation of Nps (Figure  S3b). We obtained merely the brown nanopowder in the arc fabrication experiment using a PVP aqueous medium (w/v ), at 50 A [13, 32]. Due to coordination between Cu and PVP, the oxidation of Cu Nps is avoided. Its XRD and SEM results show pure Cu Nps with average grain size of 50 nm, respectively (Figure  S4).

3.2. TEM Analysis

Using the current of 50 A (current of choice), TEM images of Cu Nps illustrate their spherical morphologies, confirming the SEM images (Figures 4 and 1(a)). To the best of our knowledge, this is the first report on the arc synthesis of metallic Cu Nps with such a fine particle size. Assuming that an Np is spherical, the average diameter of Nps is estimated to be about 20 nm by averaging the diameters of the 50 particles measured in several directions in the TEM image, which is remarkably different with those primarily estimated through SEM (58 nm) analysis, indicating high precision of TEM apparatus. However, small particles aggregate into second particles because of their extremely small dimensions and high surface energy (Figure 4(a)). The selected-area electron diffraction (SAED) pattern displays that the Nps are multiple-surface orientated consisting mainly of Cu atoms with a face-center cubic (fcc) structure (Figure 4(b)). The three characteristic diffraction rings are made of diffraction spots corresponding to (111), (200), and (220) faces of the fcc Cu crystal from the inside to the outside diffraction ring, respectively. This result confirms XRD findings (Figure 2).

3.3. TGA-DTA Analysis

Decomposition kinetics and thermal stabilities are deduced through TGA-DTA, on 5 mg samples of the preheated Cu Nps (arc fabricated at 50 A, as the best current) (Figure 5). Rather rapid weight decrease is observed at , due to vaporization of the residual water contents, with weight losses of about 0.4%, showing small exothermic peak on DTA. No significant weight loss is observed in the range of , where the weight remains constant, indicating no quantitative oxidation behavior of Cu Nps by TGA-DTA. This result shows thermal stability of the Cu Nps in distilled water at 50 A. The decomposition of particles begins at (weight regular decrease on TGA curve, Figure 5).

4. Conclusion

Cu Nps are prepared in a large scale arc discharging with homemade apparatus at different currents (50–160 A). Density of current is found as a key factor for the morphology, controlling particle sizes, and yields of Cu Nps. It is found that decreasing the current results in a substantial decrease in the particle size. According to SEM results, the trend of Cu Nps size is proportional to working current showing 50 A (  nm) 70 A (  nm) 90 A (  nm) 100 A (  nm). 50 A appear the best current for fabrication of pure, small, and high yield of Cu Nps. The TEM images show that the Cu Nps are spherical with a narrow particle size distribution and an average particle size of 20 nm (58 nm indicated by SEM). Its XRD and SEAD results indicate the fcc structure of synthesized Cu Nps. Changing current has significant effects on the particle size, while it does not show impact on the Cu Nps compositions.

Acknowledgment

The authors wish to thank Mr. Rezaee (SEM) and Mrs. Fardindost (XRD) for their support. The authors gratefully acknowledge the Iran Nanotechnology Initiative Council (INIC) for financial support.

Supplementary Materials

Figure 1. Effects of four different currents (50-100A) on the size distributions of the arc fabricated Cu Nps, in distilled water calculated on the basis of the corresponding SEM images (Figure 1a-d).

Figure 2. Characterizations of a sample of the watery black nanopowders, arc fabricated at 50A: The SEM image (a), the size distribution calculated on the basis of the corresponding SEM image (b), and the XRD pattern showing a mixture of Cu, Cu2O, and CuO (c).

Figure 3. Comparison between XRD patterns of as-produced nanopowders fabricated at 50A, before and after one month storage in distilled water: the brown nanopowder containing pure Cu Nps (a), the dark mixture initially containing Cu and copper oxides nanoparticles (b).

Figure 4. Characterizations of the arc fabricated brown nanopowder obtained using an aqueous PVP medium at 50A: The XRD pattern showing pure Cu Nps as the only product (a), the SEM image (b), and the size distribution calculated on the basis of the corresponding SEM image (c).

Figure 5. Characterizations of a brown nanopowder, arc fabricated at 30A in distilled water: The XRD pattern showing pure Cu Nps as the only product (a), the SEM image (b), and the size distribution calculated on the basis of the corresponding SEM image (c).

  1. Supplementary Material

References

  1. S.-J. Park, A. A. Lazarides, C. A. Mirkin, and R. L. Letsinger, “Directed assembly of periodic materials from protein and oligonucleotide-modified nanoparticle building blocks,” Angewandte Chemie International Edition, vol. 40, no. 15, pp. 2909–2912, 2001. View at: Publisher Site | Google Scholar
  2. Z. Liu, Y. Yang, J. Liang et al., “Synthesis of copper nanowires via a complex-surfactant-assisted hydrothermal reduction process,” Journal of Physical Chemistry B, vol. 107, no. 46, pp. 12658–12661, 2003. View at: Google Scholar
  3. R. S. Rao, A. B. Walters, and M. A. Vannice, “Influence of crystallite size on acetone hydrogrnation over copper catalysts,” Journal of Physical Chemistry B, vol. 109, no. 6, pp. 2086–2092, 2005. View at: Publisher Site | Google Scholar
  4. A. A. Ponce and K. J. Klabunde, “Chemical and catalytic activity of copper nanoparticles prepared via metal vapor synthesis,” Journal of Molecular Catalysis A, vol. 225, no. 1, pp. 1–6, 2005. View at: Publisher Site | Google Scholar
  5. S. Cai, X. Xia, and C. Xie, “Research on Cu2+ transformations of Cu and its oxides particles with different sizes in the simulated uterine solution,” Corrosion Science, vol. 47, no. 4, pp. 1039–1047, 2005. View at: Publisher Site | Google Scholar
  6. N. D. Nikolic, K. I. Popov, L. J. Pavlovic, and M. G. Pavlovic, “Morphologies of copper deposits obtained by the electrodeposition at high overpotentials,” Surface and Coatings Technology, vol. 201, no. 3-4, pp. 560–566, 2006. View at: Publisher Site | Google Scholar
  7. A. J. Atanacio, B. A. Latella, C. J. Barbé, and M. V. Swain, “Mechanical properties and adhesion characteristics of hybrid sol-gel thin films,” Surface and Coatings Technology, vol. 192, no. 2-3, pp. 354–364, 2005. View at: Publisher Site | Google Scholar
  8. J. P. Cason, M. E. Miller, J. B. Thompson, and C. B. Roberts, “Solvent effects on copper nanoparticle growth behavior in AOT reverse micelle systems,” Journal of Physical Chemistry B, vol. 105, no. 12, pp. 2297–2302, 2001. View at: Google Scholar
  9. S.-H. Wu and D.-H. Chen, “Synthesis of high-concentration Cu nanoparticles in aqueous CTAB solutions,” Journal of Colloid and Interface Science, vol. 273, no. 1, pp. 165–169, 2004. View at: Publisher Site | Google Scholar
  10. H. Zhu, C. Zhang, and Y. Yin, “Novel synthesis of copper nanoparticles: influence of the synthesis conditions on the particle size,” Nanotechnology, vol. 16, no. 12, pp. 3079–3083, 2005. View at: Publisher Site | Google Scholar
  11. E. Lester, P. Blood, J. Denyer, D. Giddings, B. Azzopardi, and M. Poliakoff, “Reaction engineering: the supercritical water hydrothermal synthesis of nano-particles,” Journal of Supercritical Fluids, vol. 37, no. 2, pp. 209–214, 2006. View at: Publisher Site | Google Scholar
  12. W. Hu, L. Zhu, D. Dong, W. He, X. Tang, and X. Liu, “Thermal behavior of copper powder prepared by hydrothermal treatment,” Journal of Materials Science, vol. 18, no. 8, pp. 817–821, 2007. View at: Publisher Site | Google Scholar
  13. M. Chandra, S. S. Indi, and P. K. Das, “First hyperpolarizabilities of unprotected and polymer protected copper nanoparticles prepared by laser ablation,” Chemical Physics Letters, vol. 422, no. 1–3, pp. 262–266, 2006. View at: Publisher Site | Google Scholar
  14. C. Qin and S. Coulombe, “Organic layer-coated metal nanoparticles prepared by a combined arc evaporation/condensation and plasma polymerization process,” Plasma Sources Science and Technology, vol. 16, no. 2, pp. 240–249, 2007. View at: Publisher Site | Google Scholar
  15. T.-T. Tsung, H. Chang, L.-C. Chen, L.-L. Han, C.-H. Lo, and M.-K. Liu, “Development of pressure control technique of an arc-submerged nanoparticle synthesis system (ASNSS) for copper nanoparticle fabrication,” Materials Transactions, vol. 44, no. 6, pp. 1138–1142, 2003. View at: Google Scholar
  16. C.-H. Lo, T.-T. Tsung, and L.-C. Chen, “Shape-controlled synthesis of Cu-based nanofluid using submerged arc nanoparticle synthesis system (SANSS),” Journal of Crystal Growth, vol. 277, no. 1–4, pp. 636–642, 2005. View at: Publisher Site | Google Scholar
  17. C.-H. Lo, T.-T. Tsung, L.-C. Chen, C.-H. Su, and H.-M. Lin, “Fabrication of copper oxide nanofluid using submerged arc nanoparticle synthesis system (SANSS),” Journal of Nanoparticle Research, vol. 7, no. 2-3, pp. 313–320, 2005. View at: Publisher Site | Google Scholar
  18. H. Chang, C. S. Jwo, C. H. Lo, T. T. Tsung, M. J. Kao, and H. M. Lin, “Rheology of CuO nanoparticle suspension prepared by ASNSS,” Reviews on Advanced Materials Science, vol. 10, no. 2, pp. 128–132, 2005. View at: Google Scholar
  19. C.-H. Lo, T.-T. Tsung, and L.-C. Chen, “Fabrication and characterization of CuO nanorods by a submerged arc nanoparticle synthesis system,” Journal of Vacuum Science and Technology B, vol. 23, no. 6, pp. 2394–2397, 2005. View at: Publisher Site | Google Scholar
  20. M.-J. Kao, C.-H. Lo, T.-T. Tsung, and H.-M. Lin, “Development of pressure technique of brake nanofluids from an arc spray nanoparticles synthesis system,” Materials Science Forum, vol. 505–507, no. 1, pp. 49–54, 2006. View at: Google Scholar
  21. M. J. Kao, C. H. Lo, T. T. Tsung, Y. Y. Wu, C. S. Jwo, and H. M. Lin, “Copper-oxide brake nanofluid manufactured using arc-submerged nanoparticle synthesis system,” Journal of Alloys and Compounds, vol. 434-435, pp. 672–674, 2007. View at: Publisher Site | Google Scholar
  22. W.-T. Yao, S.-H. Yu, Y. Zhou et al., “Formation of uniform CuO nanorods by spontaneous aggregation: selective synthesis of CuO, Cu2O, and Cu nanoparticles by a solid-liquid phase arc discharge process,” Journal of Physical Chemistry B, vol. 109, no. 29, pp. 14011–14016, 2005. View at: Publisher Site | Google Scholar
  23. C.-H. Lo, T.-T. Tsung, and H.-M. Lin, “Preparation of silver nanofluid by the submerged arc nanoparticle synthesis system (SANSS),” Journal of Alloys and Compounds, vol. 434-435, pp. 659–662, 2007. View at: Publisher Site | Google Scholar
  24. C.-H. Lo, T.-T. Tsung, and L.-C. Chen, “Ni nano-magnetic fluid prepared by submerged arc nano synthesis system (SANSS),” JSME International Journal, Series B, vol. 48, no. 4, pp. 750–755, 2006. View at: Publisher Site | Google Scholar
  25. C.-S. Jwo, D.-C. Tien, T.-P. Teng et al., “Preparation and UV characterization of TiO2 nanoparticles synthesized by SANSS,” Reviews on Advanced Materials Science, vol. 10, no. 3, pp. 283–288, 2005. View at: Google Scholar
  26. M. Z. Kassaee, M. Ghavami, and E. Motamedi, “Open air exploding arc synthesis of nano Cu and Cu2O,” Asian Journal of Chemistry, vol. 20, no. 1, pp. 677–680, 2008. View at: Google Scholar
  27. M. Z. Kassaee, E. Motamedi, M. Majdi, A. Cheshmehkani, S. Soleimani-Amiri, and F. Buazar, “Media effects on nanobrass arc fabrications,” Journal of Alloys and Compounds, vol. 453, no. 1-2, pp. 229–232, 2008. View at: Publisher Site | Google Scholar
  28. M. Z. Kassaee and F. Buazar, “Al nanoparticles: impact of media and current on the arc fabrication,” Journal of Manufacturing Processes, vol. 11, no. 1, pp. 31–37, 2009. View at: Publisher Site | Google Scholar
  29. J. H. J. Scott and S. A. Majetich, “Morphology, structure, and growth of nanoparticles produced in a carbon arc,” Physical Review B, vol. 52, no. 17, pp. 12564–12571, 1995. View at: Publisher Site | Google Scholar
  30. M. R. Patel, M. A. Barrufet, P. T. Eubank, and D. D. DiBitonto, “Theoretical models of the electrical discharge machining process. II. The anode erosion model,” Journal of Applied Physics, vol. 66, no. 9, pp. 4104–4111, 1989. View at: Publisher Site | Google Scholar
  31. V. I. Levitas, B. W. Asay, S. F. Son, and M. Pantoya, “Melt dispersion mechanism for fast reaction of nanothermites,” Applied Physics Letters, vol. 89, no. 7, Article ID 071909, 2006. View at: Publisher Site | Google Scholar
  32. Y. Wang, P. Chen, and M. Liu, “Synthesis of well-defined copper nanocubes by a one-pot solution process,” Nanotechnology, vol. 17, no. 24, pp. 6000–6006, 2006. View at: Publisher Site | Google Scholar

Copyright © 2010 M. Z. Kassaee et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


More related articles

1109 Views | 793 Downloads | 12 Citations
 PDF  Download Citation  Citation
 Download other formatsMore
 Order printed copiesOrder

Related articles

We are committed to sharing findings related to COVID-19 as quickly and safely as possible. Any author submitting a COVID-19 paper should notify us at help@hindawi.com to ensure their research is fast-tracked and made available on a preprint server as soon as possible. We will be providing unlimited waivers of publication charges for accepted articles related to COVID-19. Sign up here as a reviewer to help fast-track new submissions.