Single Step Morphology-controlled Synthesis of Silver Nanoparticles
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1217-Y08-40
Single step morphology-controlled synthesis of silver nanoparticles Vinodkumar Etacheri, 1, 2 Reenamole Georgekutty, 1, 2 Michael K. Seery,2 and Suresh C. Pillai1 1
Centre for Research in Engineering Surface Technology (CREST), FOCAS Institute, Dublin Institute of Technology, Camden Row, Dublin 8, Ireland
2
School of Chemical and Pharmaceutical Sciences, Dublin Institute of Technology, Kevin Street, Dublin 8, Ireland
ABSTRACT Silver nanoparticles having different size and plasmon resonances were synthesized through a single step aqueous based method. The current procedure was based on the reduction of silver ions by ascorbic acid in the presence of sodiumborohydride and trisodium citrate. Triangular colloidal nanoparticles having different plasmon resonances (and hence different size and colours) were synthesized by varying only the concentration of ascorbic acid. These nanoparticles were found to be stable without using any surfactants or polymers. This study revealed a strong correlation between particle growth and concentration of constituent chemicals. Crystallinity and phase purity of the silver samples were investigated through powder X-ray diffraction studies (XRD). Absorption spectra of various silver particles were recorded using UV/Vis/NIR spectrometer. Morphological analysis was performed using transmission electron microscopy (TEM) and average edge lengths of nanoparticles were also calculated. INTRODUCTION Shape and size control of silver nanoparticles is a promising strategy to tailor their physical and chemical properties for various applications in the field of photonics [1], catalysis [2], medical research [3] and surface enhanced Raman spectroscopy (SERS) [4]. Superior physical and chemical properties were observed for the metal nanostructures with complex shapes. A typical example is the shape and size dependent optical properties exhibited by triangular silver nanoplates. Triangular plates show three surface plasmon resonance (SPR) bands corresponding to dipole and quadruple plasmon resonance, but only one SPR band is observed for spherical silver nanoparticles. A large number of aqueous and non-aqueous methods were reported in the past decade for the synthesis of silver nanoparticles having different size and shapes such as rods, prisms, cubes, wires and disks [5-7]. For some photochemical syntheses, reaction times can be longer ranging from several hours to days. Stability of nanoparticles and use of environmental friendly chemicals are other considerations for real life applications. Recently a two step seed –mediated methods are reported for the synthesis of triangular silver nanoparticles, which involve the synthesis of spherical silver seeds and their growth into triangular nanoplates using polyvinylpyrrolidone (PVP) as a stabilizing agent [8]. Reliability of this procedure is highly dependent on the structure of silver seeds and a range of morphologies were observed in the final sol. Extreme care was required while storing the silver seeds. Because of these reasons, there
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