University of Bordeaux
Institut des Sciences Moléculaires (ISM), UMR CNRS 5255
Groupe Nanosystèmes Analytiques (NSYSA)
March 25, 2020 – 10:30
Amphi Grandjean – Build. 10 B
Dodzi Zigah is an assistant professor at the University of Bordeaux since 2010. He obtained his position after a Ph.D. with Philippe Hapiot at the University of Rennes and a postdoc at the University of Texas in Allen J. Bard’s group. In 2010, he joined the group Analytical Nanosystems (NSysA) of the Institute of Molecular Sciences (ISM). His current research focuses on electrochemistry and surface modification. He is a specialist in electrochemical microscopy and bipolar electrochemistry, to prepare and analyze hybrid materials in the fields of photoelectrochemistry and electroanalysis.
Localized Electrochemistry for Surface Modification and Analysis
"I will present the importance of localized electrochemistry, firstly to prepare heterogeneous surfaces that will combine several physicochemical characteristics and secondly to analyze surfaces. I will present two techniques, bipolar electrochemistry and electrochemical microscopy (SECM). In BPE, the conductive material is placed inside an electrolyte solution between two feeder electrodes. When the electric field is applied, oxidation and reduction reactions occur simultaneously on the conductive materials at its opposite sides. The conductive material becomes a bipolar electrode. BPE can be used to generate asymmetric micro- or nano-objects, also called Janus particles. They are particles with two different properties on the same surface. For example, we obtain surfaces that are simultaneously hydrophobic and hydrophilic, and we also develop an original drug delivery system by modifying carbon nanotubes. Electrochemical microscopy is another way of locally modifying a surface. We have developed a dual microelectrode combining a copper and a gold wire, to make local modifications based on the principle of click chemistry. We prepared optoelectrodes for the screening of the photoelectrochemical properties of TiO2 nanotubes. To finish, I will present a nanotip array produced at the surface of a coherent optical fiber bundle by a wet chemical etching step. The resulting nanostructured surface was sputter-coated with a thin gold layer. This gold film conferred plasmonic properties to the sharp nanotips and served as well as the electrode material to enable electrochemical reactions. This tip allows us to combine SECM and SERS measurements."
Figure 1 : A) Scheme of the principle of bipolar electrochemistry, B) Polypyrrole electrodeposition on one side of carbon beads, C) SEM image of optoelectrode, D) Scheme of the principle of TiO2 screening with the optoelectrode