Date of Award

5-2018

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

Committee Member

Dr. Ya-Ping Sun, Committee Chair

Committee Member

Dr. Jeffrey Anker

Committee Member

Dr. Andrew Tennyson

Committee Member

Dr. David Bruce

Abstract

Carbon dots, generally defined as carbon nanoparticles functionalized with organic molecules or polymeric species, have been the subject of much research since their initial report in 2006. The intrinsic properties of carbon dots, include bright fluorescence, low cytotoxicity, chemical inertness, photostability have led to various resulting applications leveraging them. The early research focused on synthetic approaches to produce carbon dots and their optical properties, followed by efforts exploring the mechanisms explaining the fluorescent emission, further enhancing the optical properties and finally their applications in bio-imaging, photocatlysis sensing and so on. In this dissertation, carbon dots of small carbon nanoparticles surface-functionalized with 2,2'-(ethylenedioxy)bis(ethylamine) (EDA) were synthesized, and the as-synthesized sample was separated on an aqueous gel column to obtain fractions of the EDA-carbon dots with different fluorescence quantum yields. The fractions, as well as carbon nanoparticles without any deliberate surface functionalization, were dispersed into poly(vinyl alcohol) (PVA) for composite films. In the PVA film matrix, the carbon dots and nanoparticles exhibited much enhanced fluorescence emissions in comparison with their corresponding aqueous solutions. Mechanistic implications of the results, and potential technological applications of the brightly fluorescent composite films are highlighted and discussed. Beyond the currently widely pursued carbon dots and their various applications, the coupling of nanoscale carbon with other functional materials for composite dots can provide opportunities for enhanced and/or unique applications that take advantage of the combined merits of multiple materials. Here, a facile route to prepare the carbon dots modified P25 TiO2 composites (P25/C-Dot) via thermal carbonization synthesis with microwave irradiation method was developed. The morphologies, microstructures and optical properties of the composites were investigated in detail. Also, carbon-TiO2 hybrid dots in two different structural configurations were prepared and investigated comparatively for their optical properties and photoinduced redox characteristics. Significant implications of the results to an understanding of mechanistic relationships between the hybrid nano-structures/configurations and optical/redox properties are highlighted, and opportunities in the further exploration of carbon-metal oxide hybrid dots and their applications are discussed.

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