Date of Award
2-22-2016
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Applied Science
First Advisor
Wei Zhao
Abstract
Graphene oxide (GO), a monolayer of graphite oxide and an oxidized form of graphene, has attracted tremendous attention in the last decade due to its unique physical and chemical properties. This dissertation is devoted to three research areas: 1) The hydration behaviors of GO membranes, 2) The thermal reduction behaviors of GO membranes and the GO and reduced GO (RGO)-based filtration membranes for water purification, and 3) Photo- and electro-catalytic water splitting properties of GO-based derivatives and nanocomposites with other catalytic nanomaterials for hydrogen and oxygen production. 1) The hygroscopic nature of GO and the hydration behavior of trapped water molecules within GO membranes under different levels of humidity have been studied by monitoring the uptake of water (H2O), deuterated water (D2O) and HDO in GO membranes using FT-IR spectroscopy, which have revealed crucial hydration information of GO for future ultrafast dynamic studies on water permeation in GO membranes. 2) The thermal reduction behaviors of GO have been studied based on various characterization methods. GO and reduced GO (RGO) have been used to make filtration membranes for water purification involving NaCl, KNO3, KMnO4, and Rhodamine B as model molecules. At a thickness of 0.5 mm and a permeation rate 13 L h-1 m-2 bar-1, 10 times faster than that of thin-film composite membranes used for desalination, RGO-based filtration membranes are able to remove KMnO4 with a rejection rate >99%. 3) GO membranes have been used as a scaffold to support Ni-based nanoparticles and the resulting RGO-NiO/Ni nanocomposite membranes have been determined to be an efficient oxygen evolution reaction (OER) electrocatalyst for water splitting. In addition, nickel and iron oxides have been successfully integrated into a three-dimensional (3D) RGO foam network through a facile, one-pot hydrothermal reaction approach. The resulting 3D RGO-NiFeOx nanocomposite foams have been used as a highly efficient electrocatalyst for OER. Furthermore, the electrocatalytic activities of nanosized, layered 2D molybdenum disulfide (MoS2) synthesized through a hydrothermal process have been evaluated for hydrogen evolution reaction (HER). Finally, the photocatalytic performance of pristine bismuth vanadate (BiVO4) and a nanocomposite of BiVO4 and MoS2 has also been investigated, offering new directions for solar water splitting. By using nanomaterials, this dissertation addresses critical issues related to our society, including water purification and desalination, as well as sustainable and renewable energy generation and storage, and may offer new solutions through the above-mentioned findings.
Recommended Citation
Wang, Daoyuan, "Synthesis and Applications of Graphene Oxide and Its Derivatives and Composites" (2016). Theses and Dissertations. 673.
https://research.ualr.edu/etd/673
