Nernst Equation

E(eq)=E(o)+(RT/nf)ln[Red/Ox]

Thermodynamic Equilibrium

i=0

Fast Slow

Butler-Volmer/Tafel Equations

Current Flow

i

Static Potential (Faradaic)

Fast

Nernst + Diffusion

Slow

Butler-Volmer/Tafel

Faradaic Non-faradaic

CAPACITIVE

Dynamic Potential

Controlled Potential

Cottrell Plot

y = 0.0755x - 0.0166

R2 = 0.9945

-0.050

0.000

0.050

0.100

0.150

0.200

0.250

0.300

0.350

0.400

0.450

0.000 1.000 2.000 3.000 4.000 5.000 6.000

Time ^ -1/2

Current

Double Step Chronoamperometry

N

N

W

CO

OC CO

CO

W(CO)4bpy

bpy=2,2’bipyridine

Bpy *

t2g

eg(*)

d-orbitals on tungsten

Think like an inorganic chemist!

Bpy *

t2g

eg(*)

e–

Bpy *

t2g

eg(*)

Current-Potential-Time Space

t

E

i

E

1/2

Reversible System

Potential

Time

Current