SYNTHESIS, CHARACTERIZATION AND PURIFICATION OF FUNCTIONAL NANOMATERIALS
Open Access
- Author:
- Morse, James R
- Graduate Program:
- Chemistry
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- June 08, 2017
- Committee Members:
- Raymond Edward Schaak, Dissertation Advisor/Co-Advisor
Thomas E Mallouk, Committee Chair/Co-Chair
Benjamin James Lear, Committee Member
Mary Elizabeth Williams, Committee Member
Siyang Zheng, Outside Member - Keywords:
- nanoparticles
Nanoparticle purification
Colloidal Synthesis
pyrite
selective hydrogenation
heterostructure
hybrid nanoparticles - Abstract:
- As the roles of inorganic nanomaterials continue to advance, precise control over property defining features such as composition, crystal structure, morphology and surface functionality becomes increasingly crucial. Colloidal synthesis employs solubilized chemical precursors to build materials from the bottom-up, providing an attractive method for generating nanoscale materials with extraordinary levels of control over material dimensions and morphology. In addition to the range of tunable synthetic parameters, colloidal syntheses offer solution dispersible nanoscale solids, which allows for convenient and high throughput liquid phase processing of the desired materials. Under the appropriate synthetic conditions, colloidally dispersed nanoparticle seeds can be used as structural foundations to nucleate and grow new material domains. Through this strategy, nanoparticles consisting of chemically distinct materials connected through solid state interfaces can be accessed. Dubbed “hybrid nanoparticles”, these materials constitute an expanding class of multi-component nanostructures that can exhibit multifunctionality as well as emergent phenomena not observed for the constituent materials independently. Moreover, these hybrids can adopt structures that expose multiple material domains to the surrounding media, allowing for additional synergies to be realized due to the distinct chemical surfaces arranged in close proximity. The unique features offered by these hierarchal nanostructures underpin, among many others, advanced applications in photovoltaics, biomedical theranostics, catalysis and chemical sensing. Although colloidal hybrid nanoparticles are attractive for a variety of applications, there are still significant hurdles that impair their widespread use. For example, the complex pathways that govern the heterogeneous nucleation and growth of these materials are not well understood, and accordingly, a robust synthetic framework for the modular design of hybrid structures from a diverse library of material combinations and connectivities has yet to be developed. In addition, current synthetic protocols for known colloidal hybrid architectures are nontrivial to execute, with run-to-run variability commonly observed among the product particle populations. For these reasons, studies that provide fundamental insights into colloidal reaction pathways, or offer robust strategies to access these materials in high quality, will enable key advancements in the future design and application of hybrid nanoparticle systems. In this dissertation, I present several contributions focusing on various aspects of inorganic colloidal nanoparticle chemistry. These contributions include chapters describing rigorous synthetic details as well as insights into the mechanistic pathways that govern the outcome of colloidal hybrid nanoparticle syntheses. Specifically, these studies center on the well known heterotrimer nanoparticle systems Ag-Pt-Fe3O4 and Au-Pt-Fe3O4, using them as model systems to provide generalizable insights into hybrid nanoparticle design and synthesis. In a subsequent chapter of this work, I describe new developments in the colloidal nanoparticle purification technique differential magnetic catch and release. This chapter demonstrates an alternative strategy to accessing predictable and high quality colloidal structures, by focusing on post synthetic purification rather than judicious synthetic control. Finally, an additional chapter of this dissertation describes a study investigating the selective hydrogenation of functionalized nitroarenes. These selective transformations typically require the application of complex nanoscale catalysts, which have complementary chemical surfaces in close proximity that are capable of cooperatively activating distinct reagent functionalities. The structural commonalities between heterostructured hybrid nanoparticles and these catalytic systems motivated us to investigate these transformations further and resulted in the unexpected discovery of bulk iron pyrite (FeS2) as an effective catalyst for these transformations.