Formation and Oriented Aggregation of Tabular Hexagonal Silver Particles

Lorenza Suber

doi:10.3390/condmat3020013

Abstract

Silver tabular hexagonal particles (<diagonal> = 200 nm) were prepared at 40 °C by the reduction of silver nitrate with ascorbic acid in a solution of a polynaphthalene sulphonic dispersant agent, Daxad 19, in strong acidic conditions. By varying the reaction temperature and thus the dispersion viscosity between 10 °C and 30 °C, mesostructures of silver flat rods and flakes were obtained, the former resulting from linear aggregation of tabular hexagonal particles and the latter formed by intertwined flat rods. The results indicate an easy way to tune the aggregation of particles to obtain ordered mesostructures.

Highlights

Noble metal nanoparticles have attracted considerable attention in the last few decades due to their unique optical, electric, catalytic, and antibacteriostatic properties
By varying the reaction temperature and the dispersion viscosity between 10 ◦C and 30 ◦C, mesostructures of silver flat rods and flakes were obtained, the former resulting from linear aggregation of tabular hexagonal particles and the latter formed by intertwined flat rods
All of the samples are composed of silver covered by a surfactant layer as shown by scanning electron microscope (SEM) and transmission electron microscope (TEM) investigations as well as zeta potential measurements (Figure 2) [20]

Summary

Introduction

Noble metal nanoparticles have attracted considerable attention in the last few decades due to their unique optical, electric, catalytic, and antibacteriostatic properties. Theoretical and experimental research has established that the intrinsic properties of a metal nanoparticle, which can have a great influence on its macroscopic behavior, are mainly determined by its size, composition, and crystallinity [1]. An important role in determining new macroscopic properties is attributed to the shape of the particle [8]. For example, prolate silver spheroids are effective in surface enhancement Raman scattering (SERS). The effect, compared to spherical particles, involves the splitting of the dipole resonance into two absorptions bands, in which the induced dipole oscillates along and transverse to the spheroidal axis. The change-over from a spherical to an ellipsoidal shape results in a shifting of the absorption into the UV-VIS range [9]

Methods

Results

Discussion

Conclusion