Experimental class on “ Fuel Cell and Electrochemistry
Experiment setup
Equipment: CHI760D electrochemical station
Three electrode system. WE: CE: RE: Saturated Calomel Electrode
Solution: 1 . 0 × 10-3mol/L K 3 [ Fe (CN) 6] + 0.1M KCl
Lab report
Plot curves of LSV curve, and describe why current changes with sweeping voltage?
0.000010
0.000008 Scan Rate: 20mV/s
0.000006
A
u
/
t
n
e
r 0.000004
r
u
C
0.000002
0.000000
0.6 0.4 0.2 0.0 -0.2 -0.4
Potential/V
Reason: Voltage is a driving force to an electrode reactions, it is concerned with the equilibrium of electron transfer at electrode surface. As the altering of applied voltage, the Fermi-level is raised (or lowered), which changing the energy state of the electrons. Making the overall barrier
height (ie activation energy) alter as a function of the applied voltage.
(1). In this reaction, when voltage is 0.6V, there is no electron transfer, so the current is zero.
With the voltage to the more reductive values, the current increases.
(2). When the diffusion layer has grown sufficiently above the electrode so that the flux of reactant to the electrode is not fast enough to satisfy that required by Nernst Equation. The peak is obtaining.
(3). When the reaction continued, it would get a situation that there will be a lower reactant concentration at the electrode than in bulk solution, that is, the supply of fresh reactant to the surface decreased, so current decreases.
Plot the curves of CV curves with different scan rate;
0.00006
H
G
0.00004
F
E
D
0.00002
C
A
B
/
t
A
n
e
r
0.00000
r
u
C
-0.00002
-0.00004
0.6 0.4 0.2 0.0
Potential/V
From the CV curves, fill the table
Scan rate
(mV/s)
20
50
100
200
H---600mv/s
G---500mv/s
t
a F---400mv/s
R
E---300mv/s
n
a
D---200mv/s
c
S
C---100mv/s
B--- 50 mv/s
A--- 20 mv/s
-0.2 -0.4
300 400 500 600
Peak
Ipc
8.336
13.17
18.50
25.96
31.54
36.17
40.23
43.95
current
Ipa
-8.263
-13.01
-18.19
-25.26
-30.50
-34.88
-38.68
-42.12
(uA)
Ratio of Peak
1.009
1.012
1.0
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