Author ORCID Identifier

https://orcid.org/0000-0001-7832-0985

Year of Publication

2019

Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation

College

Arts and Sciences

Department

Chemistry

First Advisor

Dr. Dong-Sheng Yang

Abstract

Carbonaceous materials, especially in micro and nanoscale, are useful in optical, energy storage, electronic, and biomedical devices or technologies. Techniques have been developed for preparation and modification of the carbonaceous materials, while it is still challenging to tailor the properties of carbonaceous materials effectively and economically. Laser is a powerful tool in academic and industrial laboratories, which also plays important roles in the preparation and modification of high-performance carbonaceous nanomaterials.

In this study low-cost hydrothermal synthesis, high-temperature annealing, and Laser ablation (LAL) methods are developed to prepare functionalized carbon nanomaterials and modify their electrochemical and optical properties.

Sub-micro hollow carbon spheres are synthesized via hydrothermal carbonization and high-temperature activation without any templates. Good capacitive properties are obtained after activation. The electrochemical properties of the activated carbon spheres depend on the media of the activation. The capacitance of the activated carbon spheres significantly increases with the addition of water as an activation agent.

Carbon dots (CDs) are synthesized via a facile and economic hydrothermal (HTC) process using both small-molecule sugar (Xylose) and ground soybean residuals as precursors. The photoluminescence (PL) properties of the as-prepared and further-treated CDs are systematically studied. For the xylose-synthesized CDs, the initial green PL emission disappears after high-temperature treatment at 850 ℃ for 2 h. With further LAL treatment in NH4OH solutions, the PL emission is re-acquired, and a blue shift in emission is observed. Thus, the LAL is found to be an effective method to modify the CDs and their PL properties. For the nitrogen-doped soybean waste-derived carbon particles, they show strong blue emissions, which essentially disappear after 850 ℃ annealing for 2 hours in an argon flow. Then, PL appears again after laser ablation in a 10% NH4OH solution. The conversion from the blue emission to no emission and then back to blue emission again implies the effect of the functional groups on the PL properties of the CDs.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2020.025

Funding Information

The NSF grant CMMI-1634540 (August 18, 2016-July 31, 2010)

CMMI-1854554 (FQY) (June 6, 2019)

The grant CHE-1362102 (July 27, 2014-July 31, 2019)

CHE-1800316 (DSY) (July 27, 2018-July 31, 2021)

Available for download on Friday, January 07, 2022

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