01726 IUPAC Gold Book - diffusion layer thickness 10.1351/goldbook.D01726 D01726 current 1 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. 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 PAC, 1974, 37, 499. 'Electrochemical nomenclature' on page 513 (https://doi.org/10.1351/pac197437040499) https://goldbook.iupac.org/terms/view/D01726/html https://goldbook.iupac.org/terms/view/D01726/json https://goldbook.iupac.org/terms/view/D01726/plain 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 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. If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org . 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. 2026-05-11T21:04:12+00:00