Sonochemical synthesis and characterization of metal nanoparticle-decorated carbon supports

Date of Award

2011

Degree Name

M.S. in Chemical Engineering

Department

Department of Chemical and Materials Engineering

Advisor/Chair

Advisor: Elena A. Guliants

Abstract

Of the wide variety of nanomaterials currently under study, metal nanoparticles have seen a large amount of research activity due to their unique and useful properties and applications. Nanoparticles of noble metals such as silver, gold, and platinum are of particular interest because of their resistance to oxidation in addition to their myriad possible applications including use in catalysis, biomedical devices, and sensing. While noble metal nanoparticles are relatively easy to synthesize initially, aggregation of metal particles is a problem that frequently occurs which prevents long term stability. When particles become agglomerated, the nano-sized regime of the particles is lost which inhibits access to properties that are only exhibited at the nanoscale. Many research groups have employed the use of nanoscale carbon supports to template nanoparticle growth in order to prevent aggregation, impart long-term stability, and preserve the nanoscale properties. Sonochemistry is well suited for this task because it has the ability to combine the synthesis of various metal nanomaterials with the deposition process due to the unique conditions that acoustic cavitation initiates. In this work, silver nanoparticles were synthesized via the reduction of silver acetate and subsequently decorated onto the surface of single-walled carbon nanotubes (SWNTs). This synthesis was performed in two different solvents, either N,N-dimethylformamide (DMF) or de-ionized (DI) water, using either sonochemistry or conventional thermal heating and the products were analyzed in order to determine the optimal procedure for decorating carbon supports. Through characterization data provided by TEM, XRD, FTIR, and DSC/TGA analysis, it was determined that the sonochemical reaction in DMF provided the optimal product. This synthetic procedure for sonochemically coating carbon nanostructures with silver nanoparticles was extended to include decoration of two additional supports in the form of graphene oxide (GO) and carbon nanoparticles (CNPs) and resulted in varying degrees of success. The same sonochemistry-in-DMF procedure was then utilized to reduce two additional metal salts, gold acetate and platinum chloride, to their respective zero-valent metal nanoparticles and subsequently decorate SWNTs with these nanoparticles. XRD results showed that in all synthetic methods face-centered-cubic metal was synthesized. FTIR analysis indicated that the metal salt precursors were either successfully reduced or washed from the final products. TGA/DSC data provided information on metal content of the sample as well as thermal response. In all cases, carbon combustion was shown to occur at earlier temperatures after metal decoration. TEM was used to determine the morphology of the products and it was determined that the size of nanoparticles and extent of decoration depended upon the multiple synthetic parameters including type of solvent, energy input (thermal or sonochemical), carbon support, and metal used.

Keywords

Nanoparticles Synthesis, Nanotubes, Metal coating, Sonochemistry

Rights Statement

Copyright © 2011, author

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