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Date of Award
Campus Access Dissertation
Doctor of Philosophy in Materials Science and Engineering (PhD)
Administrative Home Department
Department of Materials Science and Engineering
Yun Hang Hu
Committee Member 1
Committee Member 2
Committee Member 3
Committee Member 4
Hydrogenated graphene has gained intensive attention with its application potentials in various fields including hydrogen storage, catalysis, electronics, and biomedicine. The recent decade has witnessed increasing research efforts on exploit of synthesis methods for hydrogenated graphene and the development of four primary synthesis approaches, namely, plasma hydrogenation, thermal cracking, Birch reduction, and electrochemical reduction. However, commonly used synthesis methods generally suffer redundant synthesis process, high startup and operation costs, requirements for extreme conditions, and low-quality products with impurities. To solve these issues, this dissertation presents a new approach to synthesize hierarchically porous three-dimensional hydrogenated graphene from the reactions between alkali metal hydrides (i.e., lithium hydride and sodium hydride) and carbon monoxide (CO) that are newly discovered by our group.
Chapter 1 provides the basic knowledge of hydrogenated graphene. Namely, this chapter reveals the structure, properties, and forming mechanism of hydrogenated graphene, summarizes recent advances in its synthesis and engineering in terms of plasma hydrogenation, thermal cracking, Birch reduction, and electrochemical reduction, and discusses its potential applications in hydrogen storage, catalysis, electronics, biomedicines, etc.
Chapter 3 introduces the methodology applied for this dissertation, including thermodynamic calculations, sample preparation, as well as characterization and data analyses.
Chapter 4 demonstrates the new chemical reaction between lithium hydride (LiH) and CO, achieving one-step catalyst-free synthesis of hierarchically porous three-dimensional hydrogenated graphene with large specific surface area (up to 494 m2/g) and a 1.31 eV band gap. The HG displays a polycrystalline nature with an average interlayer spacing of 3.97 Å and stacking thickness of 1.01 nm, indicating the domination of bilayer and trilayer structures over multilayer species. Combustion elemental analysis affords a chemical formula of CH0.33O0.12, namely, a hydrogenation degree of 33%, which can be tuned to 18% by raising the reaction temperature. It is noteworthy that the interlayer spacing of hydrogenated graphene linearly decreases with the hydrogenation degree, providing the possibility of predicting approximate hydrogenation degree from simple XRD characterization. The three-dimensional hydrogenated graphene has application potential in fields such as electronics, energy conversion and storage, and environmental decontamination.
In Chapter 5, sodium hydride (NaH) is unprecedentedly embedded inside graphene nanobubbles via the new reaction between NaH and CO. With the lightly hydrogenated graphene nanobubble as a nanoreactor for NaH, we directly observed the electron-beam-induced decomposition process of graphene-covered NaH by in situ high-resolution transmission electron microscopy with energy dispersive spectrometry and electron energy loss spectroscopy, revealing its decomposition mechanism. This can provide guidance for the design of hydrogen storage materials.
Fei, Yuhuan, "SYNTHESIS AND CHARACTERIZATION OF THREE-DIMENSIONAL HYDROGENATED GRAPHENE", Campus Access Dissertation, Michigan Technological University, 2023.