Elektróda

Elektróda is the term used in several languages for the electrode in an electrochemical cell. An electrode is a conductor through which electric current enters or leaves an electrochemical cell, establishing an interface between a solid conductor and an electrolyte. The electrode surface is where electron transfer with dissolved species occurs, governed by interfacial reactions and the electrical double layer.

In electrochemical cells, electrodes are categorized as anodes and cathodes depending on oxidation or reduction. In galvanic (discharging) cells, the anode is the negative electrode where oxidation occurs, and the cathode is positive where reduction occurs; in electrolytic cells, the roles are driven by external power and signs may differ.

The electrode potential is the tendency to gain or lose electrons; standard electrode potentials are tabulated against the standard hydrogen electrode, and can be related to ion concentrations by the Nernst equation.

Electrodes come in various materials. Inert electrodes such as platinum, graphite, or glassy carbon serve mainly as conduits for electron transfer and do not participate in the reaction. Active or reactive electrodes, including zinc, copper, silver, or nickel, can participate in the chemical reaction at the surface. Electrode surfaces may be modified to improve selectivity, reduce overpotential, or protect against corrosion.

Common configurations include working electrodes (the electrode under study), counter electrodes (completing the circuit), and reference electrodes (providing a stable potential).

Applications span batteries and supercapacitors, electroplating, electrolysis, corrosion protection, and electrochemical sensing and analysis.