Hidrogénelektroda

Hidrogénelektroda, also known as a hydrogen electrode, is a fundamental concept in electrochemistry. It refers to an electrode where hydrogen gas participates in a redox reaction. The most common and standard form is the standard hydrogen electrode (SHE).

The SHE consists of a platinum electrode immersed in a solution containing hydrogen ions (H+) at a concentration of 1 M. The platinum serves as an inert catalyst to facilitate the reaction, and hydrogen gas is bubbled over the electrode surface at a pressure of 1 atm. The electrode reaction is reversible and can proceed in two directions: oxidation of hydrogen to protons and electrons, or reduction of protons to hydrogen gas. The SHE is assigned a standard electrode potential of 0 volts by convention, making it a reference point for measuring the potentials of other electrochemical half-cells.

In practice, the SHE is difficult to maintain precisely due to challenges in controlling the activity of hydrogen ions and the pressure of hydrogen gas. Therefore, secondary reference electrodes like the saturated calomel electrode (SCE) or silver/silver chloride electrode (Ag/AgCl) are often used in laboratories. However, these secondary electrodes are calibrated against the SHE.

Hydrogen electrodes are crucial for understanding and quantifying the thermodynamic properties of chemical reactions, determining the feasibility of electrochemical processes, and in the development of electrochemical devices such as fuel cells and batteries. They are a cornerstone of electrochemical theory.