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CV test in K3Fe(CN)6 solution
Source：Corrtest
Time：2021-12-23
View：0
CV test in K3Fe(CN)6 solution
1 instrument and solution
CS350 electrochemical workstation;
Working electrode: CS920 glassy carbon electrode;
Counter electrode: CS912 Pt wire counter electrode;
Reference electrode: CS900 SCE
1.1 Pre-treatment of the working electrode
Polish the glassy carbon electrode with metallographic abrasive paper and Al2O3 (200-300) powder till the surface is mirror like. After that do the ultrasonic cleaning respectively in ethanol(1:1), HNO3(1:1) , and distilled water. Finally wash and put it in 0.5mol/L H2SO4 solution.
1.2 Solution preparation
1.00×10-2mol/L K3Fe(CN)6 standard solution: weigh and get 1.6458g K3Fe(CN)6 and dissolve it in 1000ml distilled water, the 1.00×10-2mol/L K3Fe(CN)6 standard solution is made.
0.2mol/L KNO3 solution: weigh and get 202g KNO3, and dissolve it in distilled water to make 1000ml solution. Using a pipette to add 2.5mL1.0×10-2mol/L K3Fe(CN)6 solution and 5mL 0.2mol/L KNO3solution respectively into a 50ml volumetric flask. Then pour the distilled water into the flask till the scale line and stir.
2. Experiment steps
2.1 CV curve in K3Fe(CN)6 solution
Take a certain amount of solution into the electrolytic cell, insert the three electrodes, and connect them with the electrode cable. Choose the Cyclic Voltammetry technique, set the parameters: initial potential to be -200mV, final potential to be 600mV, the scan rate to be 100mV/s, sampling interval to be 2mV, current range to be 100mA. Use high purity nitrogen to repel the oxygen in the solution for 10min. The speed of the nitrogen is appropriate if continuous bubbles appear. Stop the nitrogen and keep the solution quiet for about 30s. After that start scanning. The I-E curve is graphed, that is the CV curve of the K3Fe(CN)6 system, as shown in Figure 1..png)
2.2 CV curve in K3Fe(CN)6 solution at various scan rate
Set the scan rate at 50mV/s, 100mV/s, 200mV/s, 300mV/s, 400mV/s and 500mV/s respectively with other conditions unchanged. The CV curves are as follows..png)
Note:
1.The experiment result is closely related to the treatment of the electrode. Generally speaking, if the electrode is well treated, the experiment outcome will comply with the reversible reaction theory. Otherwise, it is Quasi reversible reaction.
2. After a scanning, please stir the solution for the next scan to avoid the accumulation effect on the surface of the electrode.
1 instrument and solution
CS350 electrochemical workstation;
Working electrode: CS920 glassy carbon electrode;
Counter electrode: CS912 Pt wire counter electrode;
Reference electrode: CS900 SCE
1.1 Pre-treatment of the working electrode
Polish the glassy carbon electrode with metallographic abrasive paper and Al2O3 (200-300) powder till the surface is mirror like. After that do the ultrasonic cleaning respectively in ethanol(1:1), HNO3(1:1) , and distilled water. Finally wash and put it in 0.5mol/L H2SO4 solution.
1.2 Solution preparation
1.00×10-2mol/L K3Fe(CN)6 standard solution: weigh and get 1.6458g K3Fe(CN)6 and dissolve it in 1000ml distilled water, the 1.00×10-2mol/L K3Fe(CN)6 standard solution is made.
0.2mol/L KNO3 solution: weigh and get 202g KNO3, and dissolve it in distilled water to make 1000ml solution. Using a pipette to add 2.5mL1.0×10-2mol/L K3Fe(CN)6 solution and 5mL 0.2mol/L KNO3solution respectively into a 50ml volumetric flask. Then pour the distilled water into the flask till the scale line and stir.
2. Experiment steps
2.1 CV curve in K3Fe(CN)6 solution
Take a certain amount of solution into the electrolytic cell, insert the three electrodes, and connect them with the electrode cable. Choose the Cyclic Voltammetry technique, set the parameters: initial potential to be -200mV, final potential to be 600mV, the scan rate to be 100mV/s, sampling interval to be 2mV, current range to be 100mA. Use high purity nitrogen to repel the oxygen in the solution for 10min. The speed of the nitrogen is appropriate if continuous bubbles appear. Stop the nitrogen and keep the solution quiet for about 30s. After that start scanning. The I-E curve is graphed, that is the CV curve of the K3Fe(CN)6 system, as shown in Figure 1.
Fig. 1. CV curve of the K3Fe(CN)6 system [K3Fe(CN)6]=5.0×10-4mol/L [KNO3]=0.2mol/L
If the electrode receives good treatment, the CV curve is reversible, and the formal potential is about+0.23V(glassy carbon electrode)2.2 CV curve in K3Fe(CN)6 solution at various scan rate
Set the scan rate at 50mV/s, 100mV/s, 200mV/s, 300mV/s, 400mV/s and 500mV/s respectively with other conditions unchanged. The CV curves are as follows.
Fig. 2. CV curve of K3Fe(CN)6 solution at various scan rate
Note:
1.The experiment result is closely related to the treatment of the electrode. Generally speaking, if the electrode is well treated, the experiment outcome will comply with the reversible reaction theory. Otherwise, it is Quasi reversible reaction.
2. After a scanning, please stir the solution for the next scan to avoid the accumulation effect on the surface of the electrode.
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