Publication Date

Spring 2017

Advisor(s) - Committee Chair

Hemali Rathnayake (Director), Kevin Williams, and Matthew Nee

Degree Program

Department of Chemistry

Degree Type

Master of Science

Abstract

Research on metal nanoparticles (MNPs) synthesis and their applications for optoelectronic devices has been a recent interest in the fields of nanoscience and nanotechnology Photovoltaics are one of such systems in which MNPs have shown to be quite useful, due to unique physical, optical, magnetic, and electronic properties, including the metal nanoparticles synthesized in this research.

Owing to the challenges with the most common physical and chemical methods of preparing MNPs, including the use of high temperatures, toxic reducing agents, and environmentally hazardous organic solvents, there is a critical need for a benign synthesis procedure for MNPs. In this work, a simple, versatile, and environmentally and economically responsible synthesis method for making iron, nickel, zinc, and bimetallic alloy nanoparticles (ANPs) has been developed and functionalization with organic capping agents were performed to form metal-organic hybrid nanocomposites with tunable properties. The size, shape, elemental composition, photophysical properties, and crystallinity of particles and their hybrids have been evaluated.

Monometallic nanostructures of iron, nickel, and zinc oxide were synthesized via aqueous-phase reduction of metal(II) chloride salts with sodium borohydride. Upon optimization of the standard method described here, reaction parameters like reaction time, reagent molar ratios, and capping-agent molar ratio were evaluated. Characterization techniques such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive x-ray (EDS), IR, and UV-visible spectroscopies, selected area electron diffraction (SAED), and power x-ray diffraction (XRD) were performed as necessary. Well-defined, reproducible nickel and iron nanoparticles were produced with average diameters of 26±4 nm and 50±26 nm, respectively, arranged into chain-like structures. Much smaller (6-9 nm) zinc oxide particles that self-assembled into single-particle thick, hexagonal hierarchical microstructures were formed from a modified standard method. Similarly, iron-nickel ANPs with the average size of 20.9±3.3 nm were also synthesized and successful grafting with the polymer capping agent, polyvinylpyrrolidone was confirmed.

Because of size, ordered self-assembly, and benign synthesis procedure, the nanoparticles described here are ideal candidates for photovoltaic and thermoelectric device applications. Moreover, these particles have shown to disperse well in various organic and inorganic media, and therefore have wide versatility in thin-film deposition methods.

Disciplines

Materials Chemistry | Nanotechnology Fabrication | Physical Chemistry

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