Title: diffusion layer thickness
Long Title: IUPAC Gold Book - diffusion layer thickness
DOI: 10.1351/goldbook.D01726
Status: current

Definition
Defined by the equation: \[\delta = \frac{D}{k_{\rm{d}}}=\frac{n\ F\ D\ c\ A}{l_{i}}\] where \(D\) is the diffusion coefficient, \(k_{\rm{d}}\) is the heterogeneous diffusion rate constant, \(F\) is the Faraday constant, \(c\) is the concentration, \(A\) is the geometric area of the electrode, \(l_{i}\) is the limiting current and \(n\) is the charge number of the cell reaction.

Related Terms
- Faraday constant: https://goldbook.iupac.org//terms/view/F02325
- charge number of the cell reaction: https://goldbook.iupac.org//terms/view/C00995
- diffusion coefficient: https://goldbook.iupac.org//terms/view/D01719
- heterogeneous diffusion rate constant: https://goldbook.iupac.org//terms/view/H02805
- limiting current: https://goldbook.iupac.org//terms/view/L03532

Source
- PAC, 1974, 37, 499. 'Electrochemical nomenclature' on page 513 (https://doi.org/10.1351/pac197437040499)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/D01726/html
- json: https://goldbook.iupac.org/terms/view/D01726/json
- xml: https://goldbook.iupac.org/terms/view/D01726/xml

Citation: Citation: 'diffusion layer thickness' 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.D01726
License: The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) for individual terms.
Collection: If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org .
Disclaimer: The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using.
Accessed: 2026-05-11T21:06:02+00:00