Coray McBean

Type

Text

Type

Dissertation

Advisor

Wong, Stanislaus S | Takeuchi, Kenneth J | Lauher, Joseph W | Dawber, Matthew

Date

2017-12-01

Keywords

LaNiO3 | Nanotechnology | Organometallic | Materials science | Oxygen evolution reaction | Synthesis | YMnO3

Department

Department of Chemistry

Language

en_US

Source

This work is sponsored by the Stony Brook University Graduate School in compliance with the requirements for completion of degree.

Identifier

http://hdl.handle.net/11401/78234

Publisher

The Graduate School, Stony Brook University: Stony Brook, NY.

Format

application/pdf

Abstract

Material properties often vary significantly at the nanoscale, as compared with its bulk counterparts. In some instances, a material of a given composition may engender unique properties when its particles are confined to the nanoscale, that are completely unseen when its particles are at the bulk scale. It follows, then, that in order to meet forthcoming technological demands, the ability to produce and discover functional nanoscale materials is crucial. Herein we present two straightforward, generalizable, and novel synthesis protocols for producing morphologically distinct mixed metal oxides with an overall formula, ‘ABO3’. The descriptor ‘ABO3’ denotes an important class of oxides, encompassing a broad range of possible compositions. Of the subset of multiferroic materials, yttrium manganese oxide (YMnO3) is highly attractive, as it features not only ferroelectric tendencies but also magneto-electric coupling which facilitates the prospects of its possible incorporation into electronic memory devices that may be operated purely by electric fields. Utilizing a unique, scalable synthetic methodology that combines metal−oleate thermal degradation with the use of a molten salt protocol, we were able to synthesize phase-pure, single-crystalline hexagonal YMnO3 nanoplates, measuring 441 ± 241 nm in diameter and 46 ± 6 nm in height. Moreover, these nanoplates gave rise to multiferroic behavior, which was confirmed by the observation of a ferroelectric phase from a combination of high-resolution TEM (HRTEM) and selected-area electron diffraction (SAED) analysis. Generalizability of the synthesis protocol has been demonstrated with the successful synthesis of lanthanum aluminum oxide (LaAlO3) submicron scale as well as nanoscale cubes. Additionally, we have demonstrated the feasibility of a novel electroless, seedless, surfactant-free, wet solution-based protocol for fabricating “high aspect ratio” LaNiO3 and LaMnO3 nanostructures. As the focus of our demonstration of principle, we have prepared as-synthesized LaNiO3 rods and correlated the various temperatures at which these materials were annealed with their resulting catalytic performance for the oxygen evolution reaction (OER). We have observed generally better OER performance for samples prepared with lower annealing temperatures. | 310 pages

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