Cyclic Voltammetry. Current-Potential-Time Space. Time. Reversible System. A New Waveform. Potential waveform: . E . E i. 0 . Diffusion Condition. For the reversible case have the standard Semi-infinite diffusion conditions plus:. Solution. 1948
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For the reversible case have the standard
Semi-infinite diffusion conditions plus:
Sevick, “Oscillographic Polarography with Periodic Triangular Voltage”, Collection of Czech. Chem. Comm., 13, 349 (1948).
Randles, “A Cathode Ray Polarograph”, Faraday Society, 44, 327 (1948).
There is no analytical solution to Fick’s second law when the boundary is time dependent. Sevick and Randles solutions was to approximate the integral with a series. While this works for the reversible case, it is not very pragmatic for more complex mechanisms.
Wait for a high speed computer (IBM main frame -1964- University of Wisconsin at Madison)
Nicholson and Shain, “Theory of Stationary Electrode Polarography”, Analytical Chemistry, 36, 706 (1964)
Myth: A reversible wave will have a 60mV peak to peak separation.
Should use all three diagnostics
MUST go over three orders in magnitude in scan rate to reliably use a diagnostic!
Implication: A single CV scan doesn’t tell you much, don’t over interpret it!
Nicholson, Anal. Chem. 38, 1406 (1966)
ClRe(CO)3phen in acetonitrile (CH3CN) + tetrabutylammonium perchlorate
Luong, Nadjo and Wrighton, JACS, 100, 5790 (1978)