Graphene: Synthesis, Characterization, Properties and Functional Behavior as Catalyst Support and Gas Sensor.
Technische Universität, Darmstadt
[Ph.D. Thesis], (2013)
Emine Kayhan PhD Thesis.pdf
Available under Creative Commons Attribution Non-commercial No Derivatives, 2.5.
Download (30MB) | Preview
|Item Type:||Ph.D. Thesis|
|Title:||Graphene: Synthesis, Characterization, Properties and Functional Behavior as Catalyst Support and Gas Sensor|
Graphene has attracted intense scientific interest due to its exceptional electrical, mechanical and chemical properties over the last couple of years. This strictly two-dimensional (2D) material has potential applications in advanced electronic devices and composite materials. The challenge is to produce large area defect-free graphene necessary for electronic applications while bulk-production at gram scale of graphene with defects enabling anchoring sites for nanoparticles is required for applications like catalysis. Herein, we report the Ni-catalyzed ambient pressure chemical vapor deposition of (APCVD) synthesis of few-layer graphene, the spatial characterization of the few-layered transparent graphene by micro Raman spectroscopy, its electrical characterization showing p-semiconductor behavior, as well as studies on the gas-sensing properties towards low concentrations of CO and H2. Moreover, APCVD and low pressure CVD (LPCVD) growth of graphene have been carried on Cu-catalyst surfaces. Effect of metal catalyst thickness and CVD growth parameters (concentrations of the gases, growth time, cooling effect etc.) were studied in detail to optimize the quality of graphene with respect to the number of layers and defects. Chemical synthesis of graphene was established by oxidation of graphite to graphite oxide (GO) and followed by reduction process. Different methods (Staudenmaier’s, Hummers’, Modified Hummers’ and Tour’s Methods) to synthesize GO were studied comparatively to have highly oxidized GO. Various reduction techniques were studied to improve the quality of chemically derived graphene (CDG). Metal nanoparticles (NPs of Au, Ni and Pd) were successfully supported on CDG and employment of Pd/CDG as catalysts in the dehydrogenation and hydrolysis of ammonia borane (AB). Moreover, metal oxide NPs of titanium dioxide (by UV-assisted method and hydrothermal method), tungsten oxide (by sonochemical method) and zinc oxide (via thermal decomposition method), were successfully deposited on CDG. Composites of CDG with TiO2 and WO3 were applied successfully in photodegradation reactions of methylene blue (MB) under UV-light. Sensing measurements of ZnO/CDG hybrid materials were conducted towards hydrogen gas at room temperature and elevated temperatures (200°C and 300°C).
|Place of Publication:||Darmstadt|
|Classification DDC:||500 Naturwissenschaften und Mathematik > 540 Chemie|
|Divisions:||07 Fachbereich Chemie > Fachgebiet Anorganische Chemie
07 Fachbereich Chemie > Physical Chemistry
|Date Deposited:||25 Oct 2013 05:36|
|Last Modified:||10 Jul 2014 22:04|
|Referees:||Schneider, Prof. Dr. Jörg J. and Buntkowsky, Prof. Dr. Gerd|
|Refereed:||12 July 2013|