electrodos

An electrode is a conductor through which electric current enters or leaves an electrochemical cell, device, or medium. In electrochemistry, electrodes provide a surface for oxidation or reduction reactions and serve as the interface between an electronic circuit and ionic species in a solution or electrolyte.

Two principal roles are distinguished: the anode, where oxidation occurs, and the cathode, where reduction occurs. The assignment of an electrode as anode or cathode depends on the device: in galvanic (voltaic) cells the anode is negative, while in electrolytic cells it is positive. Electrodes may be designed to participate in the chemistry or to act as inert conducting surfaces.

Materials and construction vary by application. Inert electrodes, such as graphite, carbon, platinum, and certain ceramics, are used when the electrode should not participate in the reaction. Active electrodes, made from metals like copper or nickel, participate in the redox process. Reference electrodes, including silver/silver chloride and saturated calomel, provide a stable reference potential for measuring electrode potentials. Electrode surfaces are often engineered with coatings or porous structures to control overpotential and mass transport.

Common applications span energy storage, synthesis, and sensing. In batteries and fuel cells, electrodes are the sites of charge transfer. In electrolysis, they drive chemical changes such as chlorine production or metal plating. In corrosion protection, sacrificial anodes corrode preferentially to shield structures. In sensors and medical devices, surface or implanted electrodes detect electrical activity or deliver stimulation.

Measurement considerations include standard electrode potentials, reference conventions, and impedance at the electrode–electrolyte interface. Proper electrode selection and maintenance are essential for performance, durability, and safety across applications.