Radiolytic synthesis of bimetallic silver-palladium and silver-platinum nonoparticles with high aspect ratios

Author

Carmen M. Doudna

Abstract

"In this work a method to synthesize bimetallic nanoparticles with high aspect ratio is presented. Aqueous solutions containing ions of noble and transition metals (Ag-Pd and Ag-Pt) are exposed to gamma radiation in the campus nuclear reactor. Interaction of the gamma rays with water molecules produces solvated electrons that reduce the metal ions to their neutral state. A water-soluble polymer is added to the solution to control the size and aspect ratio of the nanometer size metallic clusters. The clusters have been characterized with transmission electron microscopy (TEM) and X-ray Absorption Fine Structure (XAFS), to determine if they have a crystalline structure for all metal molar ratios and to determine the degree of alloying. The most relevant finding of our experiment is that the particles are wire-like. The high aspect ratio of the nanoparticles is surprising since nanoparticles obtained with most other synthesis methods, including radiolysis, are spherical. To understand the mechanism of formation of the high aspect ratio nanoparticles several experimental parameters are varied, such as total radiation dose, radiation dose rate, type of polymer, metal and polymer concentration, and type of counterions in solution. The most relevant parameters affecting nanowire formation are the counterions added to the solution, the relative metal concentration, and the capping polymer. Based on the available experimental evidence, it is proposed that nanowires grow from seeds formed in the early stages of irradiation. The polymer, metal ions, and counterions probably assist nanowire formation by providing a high aspect ratio micellar environment. Recommendations for future experiments to understand the mechanism of nanowire formation is provided"--Abstract, page iv.

Advisor(s)

Bertino, Massimo F.

Committee Member(s)

Waddill, George Daniel
O'Keefe, Matthew

Department(s)

Physics

Degree Name

M.S. in Physics

Publisher

University of Missouri--Rolla

Publication Date

Fall 2002

Pagination

ix, 63 pages

Note about bibliography

Includes bibliographical references (pages 59-62).

Rights

© 2002 Carmen Maria Doudna, All rights reserved.

Document Type

Thesis - Restricted Access

File Type

text

Language

English

Subject Headings

Metal clustersNanotechnology

Thesis Number

T 8157

Print OCLC #

52641322

Recommended Citation

Doudna, Carmen M., "Radiolytic synthesis of bimetallic silver-palladium and silver-platinum nonoparticles with high aspect ratios" (2002). Masters Theses. 2252.
https://scholarsmine.mst.edu/masters_theses/2252