Ox and
Red represent the oxidized and reduced forms of the chemical species, respectively.
where k0 is the
heterogeneous rate constant (SI unit: m/s) and
αc is the (cathodic) transfer coefficient (dimensionless). For a one-electron reduction, the anodic and cathodic transfer coefficients are related as
αa + αc = 1.
The exchange current density i0 (SI unit: A/m
2) is then related to the heterogeneous rate constant as
i0 = k0Fc.