- Run CV of ferricyanide with a Pt working electrode in place of glassy carbon. Oxygen is reduced more readily at Pt than GC so the scan should not go below 0.0 V. Which electrode gave results closest to what is expected for a reversible electrode reaction? How close to the theoretical value of Ip did you get for the reduction of ferricyanide?
Run CVs of ferrocene carboxylic acid (FCA, concentration at 3–5 mM) in pH 7 buffer containing 0.1M KNO3. FCA is water soluble as the carboxylate ion. It undergoes a nearly ideal one-electron transfer reaction without any complications. The Ep separation between the Epa and Epc should be close to the theoretical value. Do scan rate studies and tabulate Epa, Epc, (Epa + Epc)/2, and the Ipa and Ipc (corrected for baseline) in your report. Comment on FCA’s electron transfer reversibility compared to ferri/ferrocyanide.
The F.W. of FCA is 230.04. It can be purchased in small quantities from Sigma Aldrich chemicals. Please read the manufacturers label about care in handling.
An example CV for the oxidation of FCA at a GC electrode is shown in Figure 2.
Figure 2. CV for the oxidation of 2 mM ferrocene carboxylic acid at pH 7. Scan rate is 100 mV/s