Title: mercury electrode
Long Title: IUPAC Gold Book - mercury electrode
DOI: 10.1351/goldbook.09102
Status: current

Definition
Liquid metal electrode used in polarography.

Notes
1) Liquid mercury is an ideal electrode material for negative potentials because of its high overpotential for hydrogen evolution (electrochemical reduction of hydroxonium cations from solution). However, mercury is readily oxidized, particularly in the presence of anions that form complexes or that precipitate with \(\ce{Hg(I)}\) or \(\ce{Hg(II)}\) ions, and thus it is not suitable for use at positive potentials. The use of liquid mercury has largely been discontinued because of concerns about the toxicity of the element and its compounds.
2) A mercury film electrode (MFE) or thin mercury film electrode (TMFE) is formed by coating a conducting substrate, usually glassy carbon, with a layer of mercury (thin film, amalgam, or array of microdrops), often by electrodeposition from a solution containing \(\ce{Hg(II)}\). The electrode area is normally in the range of \(\pu{0.1 to\, 0.5 cm2}\) and mercury film thickness typically ranges from \(\pu{10 to 1000 nm}\), producing a film of large surface area-to-volume ratio that results in a high analyte pre-concentration during the deposition step of anodic stripping voltammetry. Compared to an HMDE, the MFE provides high sensitivity and resolution; however, it is somewhat less reproducible and more prone to interferences from intermetallic formation and surface-active substances.

Related Terms
- HMDE: https://goldbook.iupac.org//terms/view/09103
- anodic stripping voltammetry: https://goldbook.iupac.org//terms/view/09152
- electrode: https://goldbook.iupac.org//terms/view/09060
- polarography: https://goldbook.iupac.org//terms/view/09135

Source
- PAC, 2020, 92, 641. 'Terminology of Electrochemical Methods of Analysis (IUPAC Recommendations 2019)' on page 660 (https://doi.org/10.1515/pac-2018-0109)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/09102/html
- json: https://goldbook.iupac.org/terms/view/09102/json
- xml: https://goldbook.iupac.org/terms/view/09102/xml

Citation: Citation: 'mercury electrode' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.09102
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Accessed: 2026-04-18T11:05:03+00:00