DISSERTATION

________________________________________________________________ Experimental Work
Figure 5.3. Cyclic voltammogram (20 th cycle) of a bare polycrystalline gold electrode in
0.5 M H2SO4 at 100 mV/s scan rate. The area under the reduction peak is marked in green.
5.4 Determination of the potential of zero charge
The determination of the potential of zero charge was done via potentiodynamic
electrochemical impedance spectroscopy (PDEIS) in PB/K2SO4 solution of different ionic
strength – 10 mM PB with 20 mM K2SO4, 1 mM PB with 2 mM K2SO4 and 0.1 mM PB with
0.2 mM K2SO4. Prior to experiments, the solutions were purged with argon for at least half an
hour and the electrodes were prepared as explained in Chapter 5.3. A capacitive bridge
(capacitance of 2 µF) was used during measurements to avoid artifacts from the potentiostat
(Figure 5.4). The electrochemical setup consisted of a big cylindrical Pt counter electrode
surrounding the working electrode and a Pb/PbF2 reference electrode that was placed below the
working electrode.
Determination of the pzc of the bare electrode was done immediately after electrode preparation
to avoid any contamination of the surface. PDEIS was done for a potential range of -0.2 V to
0.7 V vs. Ag/AgCl (3 M KCl) with 30 mV potential steps. EIS was performed at each potential
step for a different range of frequencies, depending on the ionic strength and each potential was
superimposed with an AC perturbation of 10 mVpp amplitude.
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