Tafel curve of copper electrode
The half-cell reaction for copper is:
Cu2+ + 2e- → Cu ; Eo = +0.34V
The exchange current density is io = 1 A m-2
For the Tafel equation:
\[\eqalign{ & \eta = a + b\log \left( i \right) \cr & {\rm{ }} = a + b\log \left( {{i \over {{i_o}}}} \right) \cr} \]
The Tafel slope is given by:
\[b = \pm 2.303\left( {{{RT} \over {\alpha ZF}}} \right)\]
Taking:
T = 300 K
α = 0.5
Z = 2
We get:
bA = 0.059 V/decade of current
and
bC = -0.059 V/decade of current
For the anodic curve: ηA = EA – Eo
EA = Eo + ηA
For the cathodic curve: ηC = EC – Eo
EC = Eo + ηC
The plot of this is shown on the diagram below: