What is the role of the cathode in an electrochemical cell?

The cathode in an electrochemical cell is defined as the electrode where reduction takes place. In the context of electrochemical reactions, reduction refers to the gain of electrons by a substance. During the operation of an electrochemical cell, the cathode attracts cations from the electrolyte, where they receive electrons and thereby undergo reduction. This process is fundamental to the function of both galvanic (voltaic) and electrolytic cells.

For a galvanic cell, the cathode is typically the positive electrode, as it is where the electrons from the external circuit enter the cell. In contrast, in an electrolytic cell, the cathode is the negative electrode, where an external power source drives the reduction reactions. The critical understanding here is that the cathode is integral to the cell's overall energy conversion process as it facilitates essential reactions that enable the flow of current and the overall electrochemical functionality. Therefore, recognizing the cathode's role in reduction helps to grasp the electrochemical principles that govern various applications, such as batteries and electrolysis.