Effect of Temperature on the Growth of Silver Nanoparticles Using Plasmon-Mediated Method under the Irradiation of Green LEDs

Abstract

Plasmon-mediated shape conversion of spherical silver nanoparticles (NPs) to nanostructures with other shapes under the irradiation of green LEDs (520 ± 20 nm, 35 mw/cm2) at various temperatures (60, 40, 20, 10, 5, and 0 °C) was performed in this study. It was found that the bath temperature used in the reaction can influence the reaction rates, i.e., the times needed for the shape transformation process were 5, 11.5, 25, 45, 72, and 100 h at 60, 40, 20, 10, 5, and 0 °C, respectively. In addition, the bath temperature can also alter the morphologies of the final products. The major products are silver nanoplates at 60, 40 and 20 °C. However, they became decahedral silver NPs at 5 and 0 °C. The percentages of decahedral silver NPs synthesized at 60, 40, 20, 10, 5, and 0 °C are 0%, 1%, 5%, 45%, 73%, and 89%, respectively. Measuring the surface-enhanced Raman spectroscopy (SERS) spectra of the probe molecule R6G in the presence of KBr showed that both silver nanoplate colloids synthesized at 60 °C and decahedral silver NP colloids synthesized at 0 °C in the absence of PVP had good SERS activities.

Antimicrobial dependence of silver nanoparticles on surface plasmon resonance bands against <em>Escherichia coli</em>

“…The dynamic phase separation of PEG may lead to the metal complexation and partition due to chemical participation of solvated anion from the polyethylene oxide chains 6,17,44. In addition, at a temperature between 80°C and 100°C, NaOH reacts with PEG and precipitate 5,45,46…”

Two-Dimensional Colloidal Nanocrystals

“…In such a synthesis, the excitation light (of a wavelength usually chosen at the plasmon resonance energy of the NP) is absorbed by NPs, and creates an electron-hole pair where the electron reduces the metallic precursors for further growth, while the hole oxidizes the ligands on the surface on NPs. 328,329 This method has been used to grow silver nanoprisms by Maillard et al 329 The ligand used in this synthesis was citrate. Although the final size of the NPs can be controlled by the wavelength of the irradiation light (the NP grows until it stops absorbing light at this particular wavelength), the latter does not seem to play a role in the control of the thickness of the NPs, 330,331 suggesting that the final anisotropy of the NPs is not due to the irradiation, but to some intrinsic properties of the initial seeds or ligand templating, as described previously.…”

One‐Pot Synthesis of Icosahedral Silver Nanoparticles by Using a Photoassisted Tartrate Reduction Method under UV Light with a Wavelength of 310 nm

“…[25,26] In the plasmon-mediatedp rocess, smaller quasi-spherical AgNP seeds, prepared in ac hemical reduction by usingN aBH 4 ,w ere neededt ol ower the activation energy of shape transformation under light irradiation. [28] Through some modifications of this method,h exagonal nanoplate, [29] tetrahedral, [30] bipyramidal, [31] decahedral AgNPs, [32][33][34][35] and penta-twinnedA gn anorods [36] can also be successfully synthesized. Recently,Y ang et al successfully developed ap hotoassisted citrate reduction method [37] to synthesize high yields of Ag nanodecahedra under blue LED illumination without the preparation of Ag seeds before irradiation.…”