DISSERTATION

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Results and Discussion
In addition to the roughness factor (for its determination see Section 5.3), the criterion for
efficiency of electrochemical cleaning in H2SO4 was the shape of the CV. The electrode surface
was considered clean only if the oxidation peaks of individual gold facets 69 were observed upon
electrochemical cleaning as shown in Figure 3.3.
Figure 3.3. Representative CV of a clean gold electrode. Electrochemical cleaning was
performed in 0.5 M H2SO4 at a scan rate of 100 mV/s.
Following the mechanical and electrochemical cleaning of the electrode surface, EIS and CV
using the ferro/ferricyanide couple as redox probe were used to verify the electrode cleanliness
and to allow for a comparison of separate electrodes. Afterwards, criteria were selected for the
desired charge transfer resistance (Rct) derived from EIS and the peak current in the CV as a
prerequisite for the use of prepared electrodes for subsequent surface modification.
Representative EIS and CV of clean gold electrodes are shown in Figure 3.4.
Modification of electrodes was performed immediately after mechanical and electrochemical
cleaning and characterization of the bare electrodes since it was observed by EIS that upon
storage of bare gold electrodes in air, H2SO4 or HClO4 unknown contaminants adsorb on the
electrode surface (data not shown).
3.1 Importance of preparing the surface. Criteria for cleanliness 32