Publication Date

Spring 2017

Document Type

Project Summary

Degree Name

Master of Science

Department

Analytical Chemistry

First Advisor

K. G. Sanjaya Ranmohotti, Ph.D.

Abstract

Considerable efforts have recently been devoted to the fabrication of metallic nanostructures on account of their tunable morphologies which can lead to new and fascinating optical properties. These properties of a metallic nanostructure are most determined by their size, shape, composition and structure. Hollow metallic nanostructures have attracted much interest as their surface plasmonic properties and catalytic activities are completely different from those of solid nanoparticles. Galvanic replacement reaction (GRR) was known to be a powerful synthetic technique for converting solid metal nanostructures into hallow ones. These hollow nanostructures have high specific surface area, low density, use less material and are cost effective. On the other hand, bimetallic-nanoparticles, in which two kinds of metals are contained in one particle, exhibit fascinating properties compared to those of the corresponding single-component particles. These particles are appeared to result from both the electronic and structural effects of the bimetallic structures. Nanoparticles fabricated from Ag-based alloys find extensive applications in catalysis, electro catalysis, and optics because their surface plasmon resonance (SPR) bands appear in the visible region. It has been reported that the surface plasmon resonance peaks of hollow bimetallic Au/Ag nanostructures could be readily tuned by controlling the Ag-Au ratio of the replacement reaction. However, fewer attempts have been made to study the optical properties of Pt/Ag and Pd/Ag based bimetallic nanoparticles compared to those of the Ag-Au system, probably because Pt and Pd nanoparticles do not usually exhibit surface plasmon resonance peaks in the visible spectrum. However, it has been demonstrated recently that the surface plasmon resonance peak of Pd nanoparticles could be tuned to 520 nm by the formation of large hollow nanocages. Hence, in this project, we have shown the efforts to come up with a new synthetic route for the controllable synthesis of Pt/Ag and Pd/Ag based bimetallic nanoparticles which exhibit tunable SPR extinction peaks in the visible region by applying galvanic replacement reaction on Ag templates in the presence of K2PtCl4 and K2PdCl4 salts. This report also focuses on the investigation of the characteristic optical properties of these composite hollow nanostructures

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