Chemistry Reference
In-Depth Information
80
000
4
70
000
60
000
50
000
w
= 5.10
4
Hz
40
000
30
000
w
=1
MHz
20
000
w
= 0.1-10
4
Hz
10
000
3
1-2
0
0
50
000
100
000
150
000
(a)
Z
r
10
000
9000
8000
3
7000
6000
5000
4000
3000
2000
1000
2
1
0
0
5000
10
000
15
000
20
000
(b)
Z
r
9.2
Nyquist plot recorded at an electrochemical cell with palladium
electrodes of 314 mm
2
at a distance of 112 mm for a NaCl con-
centration of (1) 1
¥
10
-
1
, (2) 1
¥
10
-
2
, (3) 1
¥
10
-
3
and (4) 1
¥
10
-
4
mol l
-
1
at
T
=
298.0 K. Figure 9.2b is an enlargement of Fig. 9.2a.
put in the electrochemical cell, already containing the palladium electrodes,
and the electrochemical impedance of the cell was obtained by applying an
alternating potential and measuring the resulting alternating current in the
frequency domain of 0.1-1 MHz. In order to investigate the contribution of
the electrolyte solution to the impedance only, the other parameters were
kept constant at values of
A
= 314 mm
2
and
d
= 112 mm. Nyquist and Bode
plots of these experiments are shown in Fig. 9.2 and Fig. 9.3. The data show
