électrode

An electrode is a conductor through which an electrical current enters or leaves a medium. This medium can be an electrolytic solution, a semiconductor, a vacuum, a gas, or another electrical circuit. Electrodes are fundamental components in many electrical and electrochemical devices.

In electrochemistry, electrodes are used in cells to facilitate redox reactions. The anode is the electrode where oxidation occurs, and the cathode is the electrode where reduction occurs. The names anode and cathode are defined based on the direction of electron flow or ion movement, which can vary depending on whether the electrochemical cell is galvanic (producing electricity) or electrolytic (consuming electricity). For instance, in a galvanic cell, the anode is negative and the cathode is positive, whereas in an electrolytic cell, the anode is positive and the cathode is negative.

Electrodes are made from a variety of conductive materials, including metals like platinum, gold, silver, copper, and nickel, as well as carbon-based materials like graphite. The choice of material depends on the specific application, considering factors such as conductivity, reactivity, cost, and durability.

Common applications of electrodes include batteries, fuel cells, electroplating, sensors, and medical devices like ECG electrodes. In electronics, electrodes are also found in vacuum tubes, transistors, and integrated circuits, serving as points of connection for electrical signals. The precise design and composition of electrodes are critical for the efficient and reliable operation of these devices.