Synthesis and Applications of Gold and Gold-copper Alloy Nanoparticles
Open Access
- Author:
- Motl, Nathan Edward
- Graduate Program:
- Chemistry
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- May 10, 2012
- Committee Members:
- Raymond Edward Schaak, Dissertation Advisor/Co-Advisor
Lasse Jensen, Committee Member
Thomas E Mallouk, Committee Member
Robert Martin Rioux Jr., Committee Member - Keywords:
- colloidal hybrid nanoparticles
nanoparticle heterodimers
chemical transformations
AuCu
Au
Cu2S
plasmon
alloy nanoparticle
composition tunable - Abstract:
- The unique physical and chemical properties of noble metal nanoparticles have enabled the materials to be utilized as invaluable tools for use in a wide range of disciplines. Many of these applications depend on the ability to intelligently modify the material shape, composition and structure. Low temperature solution methods have been shown to produce colloidally stable nanomaterials with a variety of shapes and compositions. In this dissertation I describe our recent contributions to the development and application of complex nanomaterials, specifically gold and gold-copper alloy nanoparticles. We first demonstrate the synthesis and investigation of composition-tunable gold-copper alloy nanoparticles. This investigation was undertaken to examine the relationship between the alloy nanoparticle composition and the resulting optical properties. Specifically, highly uniform particles were examined using both powder X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS). The resulting optical activity of the nanoparticles was compared with the theoretically predicted UV-Vis absorbance spectra. This study serves as a methodology template by which existing theoretical models can be tested with more complex systems. Next we describe the novel synthesis of Au-Cu2S hybrid nanoparticles via the phase segregation of AuCu alloy nanoparticles. Hybrid nanoparticles are characterized by discrete inorganic domains that are bound together through a solid-solid interface. These particles are often formed by nucleating the growth of a second inorganic domain on the surface of an existing particle through a seed mediated approach. As the complexity of nanomaterial synthesis and application increases, additional synthetic routes to these materials will be required. By heating AuCu alloy nanoparticles in the presence of sulfur it was possible to phase segregate the copper component to generate Au-Cu2S heterodimers with discrete Au and Cu2S components. The resulting particles were examined extensively with transmission electron microscopy (TEM), energy electron loss microscopy, (EELS), XRD, EDS and UV-Vis absorbance spectroscopy. Additional control experiments were performed to support the phase segregation route to hybrid nanoparticles. This process demonstrates a new method of nanomaterial synthesis that can draw upon a vast library of alloy and intermetallic nanoparticles as precursor materials Lastly, we demonstrate the use of both gold and copper nanoparticles for the fabrication of mesoscale components through modifying the existing lost mold – rapid infiltration forming (LM-RIF) process. Several generations of components with nano- and microscale features were shown with progressivessive improvements on part fabrication. This work served as a proof of concept, demonstrating a general technique that could incorporate the vast array of metal nanoparticles available into part fabrication. In addition to the miniaturization of existing components, this process could potentially lead to such medical advances as microsurgical instruments and localized drug delivery.