Antec Scientific ROXY Exceed, User Manual, Page: 65 / 126

Chapter 5 Measurement modes 65
Fig. 21. Top: Plot of cell potential versus time. Bottom: DC mode method
settings window in Dialogue Elite. The potential (top right) can be set be-
tween -4.9 and +4.9 Volt.
The DC mode can be used for oxidation and reduction reactions using rel-
atively inert working electrode (WE) materials such as Glassy Carbon (GC)
or Boron-Doped Diamond. Suitable target compound in this case are typi-
cally aromatic compounds with functional groups which can be easily oxi-
dized at relatively low potentials. In addition, one other requirement for
successful operation in DC mode is that the target compounds and reac-
tion products should not easily absorb or contaminating the electrode sur-
face leading to inactivation of WE electrode activity and subsequent loss of
conversion efficiency of the electrochemical reaction.
Pulse mode
Besides the DC mode the ROXY Exceed can also be operated in Pulse
mode. The pulse mode is quite different from the DC mode. Instead of a
constant potential, a series of potential steps is applied in a cyclic manner.
The signal is sampled during a fraction of the total pulse cycle. During the
sampling time (ts) the signal is collected and this value is sent to the po-
tentiostat output. The frequency of data output is determined by the pulse
duration: t1 + t2 + t3 + t4 + t5. Usually the duration is between 0.5 and 2s
(data rate between 2
– 0.5 Hz).
Fig. 22. Pulse mode example: Plot of a three-step potential waveform
(grey curve) versus time. Red part: time during which the current signal is
measured.
This mode is particularly useful for certain applications where the working
electrode is rapidly fouled due to adsorption of reactant or reaction prod-
ucts or/and when using metal electrodes like gold, platinum, titanium elec-