Mehtap Oezaslan, Dr.
room: W03 1-117
fon: +49 (0)441 798 3917
fax: +49 (0)441 798 3979
Carl von Ossietzky Universität Oldenburg
School of Mathematics and Science
Department of Chemistry
26111 Oldenburg Germany
Bachelor and Master Thesis
-> If you are interested in research activities for energy conversion, ...
-> If you are highly motivated to learn new methods and techniques, ....
-> If you want to gain experience in the field of nanoparticle synthesis, structural characterization as well as electrochemical characterization by using modern techniques, ...
then you should apply for a thesis (Bachelor/Master) to the Chair of Electrocatalysis Group.
Three steps to apply for a thesis:
1) Choose a research topic at our group
2) Select a topic from the list of possible topics below.
3) Send your application including Curriculum Vitae and "Notenauszug" to the Chair of Electrocatalysis Group.
For more information, do not hesitate to contact us.
Synthesis of Shape- and Size-Controlled Metal Nanoparticles
... is of large interest in the field of Electrocatalysis. In this project, nanoparticles with controlled chemical composition, particle size and particle shape will be synthesized by modern colloidal methods. By tuning the chemical composition, particle shape and particle size, the reactivity, selectivity and durability of metal nanoparticles will be tailored for various electrochemical reactions. The structure of pristine nanoparticles will be characterized by high-resolution transmission electron microscopy and X-ray diffraction methods. Preliminary electrochemical investigations using cyclic voltammetry and RDE technique will be performed to evidence the improvements in activity, selectivity and durability for the corresponding electrochemical reactions.
Modification of Pt-Metal Alloy by De-alloying for Oxygen Reduction Reaction
……..has been one of the strategies to enhance the activity of fuel cell electrocatalysts and to reduce cost of noble metal loadings. The improved activity of oxygen reduction reaction by Pt-M alloys is attributed to the change in electronic surface structure and the geometric effects due to the presence of the alloying metal in the sub-layers. Pt-M alloys (M=Cu, Co, Ni…) supported on high surface area carbon will be synthesized by impregnation method. Furthermore, Pt-M alloys systems can be de-alloyed by electrochemical cycling to high potentials (1.2 V) or by acidic leaching. Significant activity enhancements for ORR have been achieved with de-alloyed Pt-M catalysts. Our group aims to link the composition, structure, morphology and electrochemical behavior of the dealloyed Pt-M nanoparticles to ORR activity.
Design and Modification of Carbon Support Materials for Fuel Cell Applications
….have recently emerged as a promising strategy to improve the durability of electrocatalysts. Due to the high anodic potential (up to 1.5 V/RHE) during the start-stop conditions the cathode electrocatalysts strongly suffer from the corrosion of carbon support material (C + 2H2O → CO2 + 4H+ + 4e–; EO = 0.207 V/RHE) associated with particle detachment and dissolution of Pt nanoparticles. Generally, carbon is thermodynamically not stable in the potential regime of oxygen reduction reaction. In this project, various strategies like increase of graphitization, integration of other atoms (N, S) in the carbon framework, surface modification by inserting functional groups will be developed. Afterwards, the modified carbon materials will be used as support materials for Pt nanoparticles and will be electrochemically investigated by RRDE technique.
Electrochemical Ethanol Oxidation on Pt-based Nanoparticles
.... has recently attracted great attention. Ethanol is very interesting for fuel cells because it exhibits high energy density, low toxicity compared to other alcohols like methanol, ease of storage and transportation and it can be obtained largely from biomass. However, the world-wide commercialization of ethanol fuel cells is hindered by the very sluggish kinetics of the ethanol oxidation reaction (EOR) towards CO2 (C2H5OH + 3 H2O -> 2 CO2 + 12 H+ + 12 e-). The goal of this project is to prepare Pt-Sn-based nanoparticles for the EOR. The chemical composition, particle size and crystallinity will be correlated with the resulting activity, selectivity and durability. In-situ electrochemical FT-IR spectroscopy will help to understand the kinetics and mechanisms for EOR.
Fluorescent Au-Ag Nanoparticles for Single Molecule Spectroscopy
...are promising candidates for model catalysts. Single molecule spectroscopy, e.g. fluorescence correlation spectroscopy, allows population selective detection of kinetic parameters of single particles. In contrast to single molecule techniques, traditional methods always provide an average information, ignoring possibly differing properties in nanoparticle mixtures. Performing single molecule experiments allows to separate catalytic active and inactive particles within one solution. The fluorescent properties of nanoparticles are very sensitive to size, charge and surface modification of the particles and therefore are excellent reporters for changes of the particles during the catalytic cycle.
The goal of this project is the synthesis of bimetallic fluorescent and ligand-free Au nanoparticles. These nanoparticles will first be characterized by TEM, XPS and fluorescence spectroscopy. Additional single molecule experiments will provide data about the hydrodynamic radius, which is mainly determined by the nanoparticle ligand shell.