Overvoltage
| Formula / Notation | Overpotential η = E_actual − E_theoretical; η > 0 for electrolysis |
|---|---|
| Also Known As | Overpotential, η (overvoltage), electrochemical overpotential, polarisation overvoltage |
What is Overvoltage?
The extra voltage required beyond the theoretical decomposition potential to cause electrolysis at a practical rate. Also called overpotential. Overvoltage is particularly large for gas evolution (hydrogen and oxygen) and depends on electrode material and current density.
Formula & Notation
Other Names / Synonyms: Overpotential, η (overvoltage), electrochemical overpotential, polarisation overvoltage
Properties & Characteristics
Uses & Applications
Safety Information
Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.
Key Facts
Frequently Asked Questions
The extra voltage required beyond the theoretical decomposition potential to cause electrolysis at a practical rate. Also called overpotential. Overvoltage is particularly large for gas evolution (hydrogen and oxygen) and depends on electrode material and current density.
Overpotential is important in: electrolysis efficiency calculations (determining the actual electrical energy needed), industrial chlor-alkali process (choosing electrode materials to minimise overpotential), battery technology (overpotential limits practical cell voltage), and analytical voltammetr…
High overpotentials in industrial electrolysis cells mean more electrical energy is consumed as heat, increasing fire risk and energy costs. Electrode materials with inappropriate overpotential characteristics can lead to unexpected competing reactions (generating Cl₂ instead of O₂ at the anode, or …
The formula or notation for Overvoltage is: Overpotential η = E_actual − E_theoretical; η > 0 for electrolysis