TESTING IT

Cyclic voltammetry, briefly

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Cyclic voltammetry (CV) sweeps voltage up and back down while measuring current, tracing out a loop. The area inside that loop is where areal charge storage comes from. The height of the peaks on that curve is the peak current — and it tells you a lot about what's happening at the electrode.

You'll read real CV curves from this thesis later in the course — this is the tool that produces them.

THE RANDLES-ŠEVČÍK EQUATION

What sets peak current

i_p = (2.69×10⁵) n^3/2 A D₀^1/2 C₀* v^1/2

This equation predicts the peak current (i_p) on a CV curve from the number of electrons transferred (n), electrode area (A), the redox species' diffusion coefficient (D₀) and concentration (C₀*), and the scan rate (v) — how fast the voltage is swept.

Peak current is a direct readout of how a redox reaction responds to your test conditions.

READING THE VARIABLES

Bigger electrode, bigger peak

↑ Electrode area (A) More surface for the reaction → higher peak current

↑ Scan rate (v) Faster voltage sweep → higher peak current

↑ Concentration (C₀*) More redox-active species available → higher peak current

Every one of these variables scales peak current up — none of them scale it down. That's why CV curves are so sensitive to test setup.

UNIT 4 STUDY COMPLETE

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Ready for the Fab Challenge?

You've covered the Randles-Ševčík equation and what a cyclic voltammogram's peak current tells you.