Final answer:
The overpotential depends on the composition of the electrodes and the redox reaction. In an electrochemical cell, the cell potential is measured as the potential difference between two half-cells.
Step-by-step explanation:
The overpotential depends both on the composition of the electrodes and the redox reaction that will be hosted on the electrode. In an electrochemical cell, the potential difference between two half-cells is measured as the cell potential. This potential depends on various factors including the composition of the electrodes and the specific redox reaction taking place. For example, in electrolysis, an additional voltage called an overvoltage must be applied to overcome factors such as large activation energy and junction potential.