Volta potential

Volta potential (also called Volta potential difference, or contact potential difference, or outer potential difference, Δψ, delta psi) in electrochemistry, is the electric potential difference between two points ("1" and "2") in the vacuum:

• point "1" close to the surface of metal M₁;
• point "2" close to the surface of metal M₂ (or electrolyte);

where M₁ and M₂ are two uncharged metals brought into contact.^[1]

The Volta potential is named after Alessandro Volta.

Volta potential between two metals

When two metals are electrically isolated from each other, an arbitrary potential difference may exist between them. However, when two different metals are brought into contact, electrons will flow from the metal with a lower work function to the metal with the higher work function until the electrochemical potential of the electrons in the bulk of both phases are equal. The actual numbers of electrons that passes between the two phases is small, and the occupancy of the Fermi levels is practically unaffected.

Measurement of Volta potential

The Volta potential difference is measurable. It is related to the capacitance of an electrostatic capacitor, the two sides of which are made of the two metals for which the Volta potential difference is measured and the electrical charge used to load the capacitor. The Volta potential difference between a metal and an electrolyte can be measured in a similar fashion.^[2]

See also

• Electrode potential
• Absolute electrode potential
• Electrical potential
• Galvani potential
• Potential difference (voltage)
• Volt

References

1. ^ IUPAC Gold Book, definition of contact (Volta) potential difference.
2. ^ V.S. Bagotsky, "Fundamentals of Electrochemistry", Willey Interscience, 2006.