This dissertation includes two major projects. The first project investigated the great potential of polymer-derived ceramics (PDCs) as lithium-ion battery anode materials with good cycling stability and large capacity. SiCNO ceramic nanoparticles were produced by pyrolysis of polysilazane nanoparticles synthesized via an oil-in-oil emulsion crosslinking. The SiCNO nanoparticles had an average particle size of around 9 nm and contained graphitic carbon, Si3N4, and SiO2 domains. The electrochemical behavior of SiCNO nanoparticles anode was investigated to evaluate the Li-ion storage performance and understand its mechanism of Li-ion storage. The lithiation of SiCNO was observed at ~0.385 V versus Li/Li+. The anode had a large capacity of 705 mAh g-1 after 350 cycles with a current density of 0.1 A g-1. Moreover, it showed excellent cyclic stability with a capacity decay of 0.049 mAh g-1 (0.0097%) per cycle. In situ TEM analysis demonstrated that the SiCNO nanoparticles exhibit extraordinary structural stability with only 9.36% linear expansion in the lithiation process. The second project investigated the removal of heavy metals ions from wastewater using electrospun polyelectrolyte fibers of polyacrylic acid (PAA) and polyallylamine hydrochloride (PAH). Polyelectrolyte fiber mats were fabricated by electrospinning followed by thermal crosslinking. The fiber mats were evaluated for their efficiency in removing heavy metals in synthetic metal solutions. 70 %, 98 %, and 92 % removals of Pb2+, Cd2+, and Cu2+, respectively, were observed at pH 7.4. Metal ion-carboxylate complexations were studied by FT-IR spectra, which indicate carboxylate groups from PAA play important role in heavy metal ion removal.
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Doctor of Philosophy (Ph.D.)
College of Sciences
Length of Campus-only Access
Doctoral Dissertation (Open Access)
Zhang, Zeyang, "Polymer Derived Ceramic for Lithium-ion Storage, and Electrospun Polyelectrolyte Fiber for Heavy Metal Ions Removal" (2022). Electronic Theses and Dissertations, 2020-. 1119.