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Alternative title

Synthesis and DFT Investigations of Silver Nanocubes Coated with Gold Layers for Enhanced Stability for Sensing Technologies

Date of Award

Summer 2024

Document Type

Masters Thesis

Department or Program Affiliation

Chemistry

Degree Name

Master of Science (MS)

Department

Chemistry

First Advisor

Kowalczyk, Tim

Second Advisor

Bao, Ying (Materials scientist)

Third Advisor

Berger, Robert F.

Abstract

Silver nanocubes (Ag nanocubes) are one of the most important nanostructures, due to their plasmonic capabilities. However, their susceptibility to oxidation upon exposure leads to rounding of their edges or sharp corners, compromising quality and stability. A feasible option to address this issue is to deposit a second metal, such as gold (Au), which is resistant to oxidation, onto the Ag nanocubes. Regrettably, manipulating the synthetic parameters that shape Au coated Ag nanocubes is difficult. The galvanic replacement reaction between Au and Ag can erode, hollow, and disintegrate the Ag nanocubes. We explore several synthetic pathways to achieve well-controlled shaped Ag nanocubes while combining the optical properties of Ag and the stability and functionality of Au in an aqueous system. Density functional theory calculation was employed to gain a mechanistic insight into the deposition of Au atoms on Ag nanocubes. Specifically, we study the galvanic replacement reaction between Ag and gold precursor and the effect of the introduction of iodide in lowering the reduction potential of the gold precursor. The binding energy of the reaction process was evaluated with variations in the stoichiometry of gold precursor following the introduction of iodide. Absorption spectra of the resultant Au coated Ag nanocubes was also calculated within different excitation windows. The findings provide novel insights into the dynamics of the galvanic replacement reaction between Au and Ag, as well as a fresh outlook on the synthesis of bimetallic nanostructures of this kind.

Type

Text

Keywords

Silver Nanocubes, Density Functional Theory (DFT), Gold Precursor, Galvanic Replacement Reaction, Plasmonics, Bimetallic Nanostructures, Potassium Iodide, Reducing Agent, DFTB+, Quantum ESPRESSO

Publisher

Western Washington University

OCLC Number

1452124635

Subject – LCSH

Metal nanoparticles; Density functionals; Plasmonics

Format

application/pdf

Genre/Form

masters theses

Language

English

Rights

Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author’s written permission.

Rights Statement

http://rightsstatements.org/vocab/InC/1.0/

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

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