How does current density affect the rate of an electrochemical reaction?

In accordance with Faraday's laws, the rate of an electrochemical reaction at an electrode is directly proportional to the current density, which is defined as the current flowing through the cell divided by the electrode surface area.1

As current density increases, the rate of the electrochemical process generally increases. However, this relationship is subject to physical limitations regarding the transport of reacting species. As current density rises, the concentration of the discharging species at the electrode surface may begin to deviate from its bulk concentration. If the current density is increased to the point where the concentration of the discharging species at the surface reaches zero, the system reaches a "diffusion limiting current density," which represents the maximum possible rate for those specific conditions. Forcing a current beyond this limit will eventually cause the electrode potential to shift, leading to the initiation of a different electrochemical process.12