Preparation of nonaggregated silver nanoparticles by the liquid phase plasma reduction method
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Je-Jung Yun Nano Bio Research Center, Jangseong, Jeonnam 515-893, Republic of Korea
Sun-Jae Kim Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, Seoul 143-747, Republic of Korea
Do-Heyoung Kim School of Applied Chemical Engineering and Research Institute for Catalysis, Chonnam National University, Gwangju 500-757, Republic of Korea (Received 6 November 2012; accepted 22 February 2013)
The liquid phase plasma reduction method has been applied to prepare silver nanoparticles from a solution of silver nitrate (AgNO3) using a bipolar pulsed electrical discharge system. The excited states of atomic silver, hydrogen and oxygen as well as the molecular bands of hydroxyl radicals were detected in the emission spectra. As the discharge duration increased up to 10 min, silver particle peaks produced by surface plasmon absorption were observed around 430 nm. Both the particle size and the particle numbers were observed to increase with the length of the plasma treatment time and with the initial AgNO3 concentration. Spherical nanoparticles of about 5–20 nm in size were obtained with the discharging time of 5 min, whereas aggregates of nanoparticles of about 10–50 nm in size were mainly produced with the discharging time of 20 min. The cationic surfactant of cetyltrimethylammonium bromide (CTAB) added with the CTAB/AgNO3 molar ratio of 30% was shown to inhibit nanoparticle aggregation.
I. INTRODUCTION
Nanotechnology is a rapidly developing field, attracting significant investment from government, industry, and academia. Metal nanoparticles have gained much attention in recent years due to their notable properties, which are quite different from those of bulk substances, for potential applications in optical and electronic devices.1–5 Among the wide variety of metal nanoparticles, considerable efforts have been devoted to the controlled synthesis and investigation of silver metal (Ag) nanoparticles.6–8 Because of their optical, electrical and chemical properties, there is high interest in the potential applications, such as quantum dots, miniaturized electronic devices and catalysts for organic reactions.9–11 Many are now actively involved in the synthesis of these metal nanoparticles, and a variety of preparation methods can be found in the literature, such as radiation chemical reduction,12,13 chemical reduction in an aqueous medium with or without stabilizing polymers,14,15 chemical or photoreduction in reverse micelles,16,17 liquidphase plasma method,18–20 etc. Liquid-phase plasma (LPP) a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2013.59 J. Mater. Res., Vol. 28, No. 8, Apr 28, 2013
http://journals.cambridge.org
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has attracted much attention, because it is a simple and practicable method, and the size distribution, morphology, and composition of nanoparticles can be controlled easily. Metal ions can be reduced to zero-valent metal if sufficient amount of electrons are provided. In LPP, large quantity of electrons are pro
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