eDAQ Picostat, User Manual

Page: 114 / 122

110 eDAQ Potentiostats
D = diffusion coefficient of the substrate molecule (cm
2
/s)
C = concentration of the substrate molecule (mol/L)
ν
= the scan rate (V/s).
The factor of 269 is a parameter that derives from using a planar
electrode at a temperature of 298 K.
Thus a truly reversible reaction can be identified by examining the
adherence of the system to the following functions:
E
p
independence of the scan rate,
υ
In addition cyclic voltammograms will exhibit:
mV (at 298 K)
When working in highly resistive solutions, which is often the case
when using organic solvents for cyclic voltammetry, the reference
electrode should be kept as close as possible to the working electrode
to minimise iR drop. Nonetheless there may still be an appreciable
uncompensated resistance which will cause
to become larger
than predicted, the peaks to be broader, and the peak currents to be
smaller.
i
p
ν ∝
E
pa
E
pc
–
57
n
------ =
i
pa
i
pc
------- 1
=
E
pa
E
pc
–