For a redox reaction written as a reduction at the equilibrium potential, electron transfer processes continue at electrode/solution interface in both directions.
Owing to this difference, mercury is the preferred electrode material at reducing (cathodic) potentials in aqueous solution.
[1] The exchange current density depends critically on the nature of the electrode, not only its structure, but also physical parameters such as surface roughness.
Of course, factors that change the composition of the electrode, including passivating oxides and adsorbed species on the surface, also influence the electron transfer.
The nature of the electroactive species (the analyte) in the solution also critically affects the exchange current densities, both the reduced and oxidized form.