Volmer

Volmer is a surname of German origin. In science, the name is most closely associated with the German physical chemist Max Volmer, whose work helped establish modern electrochemistry. The term Volmer appears in the names of fundamental concepts such as the Volmer step and in the Butler-Volmer equation, a standard description of electrode kinetics.

Volmer reaction: An elementary electrochemical step in which a proton or water-derived species accepts an electron at an electrode to become adsorbed hydrogen. In acidic media: H3O+ + e− → Hads + H2O (often written as H+ + e− → Hads). In alkaline media: H2O + e− → Hads + OH−. The adsorbed hydrogen can subsequently react via the Heyrovsky step or the Tafel step to form molecular hydrogen.

Butler-Volmer equation: A principal relation in electrochemistry that describes current density i as a function of overpotential η for an electrode reaction. A typical form is i = i0 [exp(αa F η / RT) − exp(−αc F η / RT)], where i0 is the exchange current density and αa, αc are charge-transfer coefficients. This equation underpins modeling of fuel cells, batteries, and corrosion, and it embodies the influence of both the Volmer (discharge) and subsequent chemical steps on overall reaction rates.