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Taffit: An Excel Tool for Fitting Tafel Data
Journal article   Open access   Peer reviewed

Taffit: An Excel Tool for Fitting Tafel Data

Joshua Coduto and Johna Leddy
ACS measurement science au, Vol.5(4), pp.536-546
07/14/2025
DOI: 10.1021/acsmeasuresciau.5c00038
Appears in  UI Libraries Support Open Access
url
https://doi.org/10.1021/acsmeasuresciau.5c00038View
Published (Version of record) Open Access

Abstract

Tafel analysis is widely used to characterize electrode kinetics. The technique has found use in electrochemistry, catalysis, materials, and corrosion research. Accurate Tafel analysis is especially critical in comparison of electrocatalysts. However, classical Tafel analysis (CTA) relies on the user’s subjective selection of a linear range in the Tafel plot; dependent on linear regression of the user-selected range, kinetic parameters can vary by orders of magnitude. As use of CTA in the literature grows, a need is identified for more reliable, user-independent Tafel analysis. Here, Taffit, an algorithm constructed in the widely available Microsoft Excel, is presented. Taffit generates a Tafel plot from linear sweep voltammetric data and determines the exchange current density j0, charge transfer coefficient α, and Tafel slopes by closest statistical fit. Comparisons between Taffit and CTA are made for the hydrogen evolution reaction (HER, 2H+ + 2e ⇌ H2) on glassy carbon (GC) and platinum electrodes. Taffit finds log j0 values of −7.2 and −3.9 for GC and Pt under H2 at pH 0, as measured without resistive compensation. This is the first report of j0 for HER on GC. Because algorithmic fitting in the low overpotential region uses both cathodic and anodic branches of the Tafel plot, Taffit has greater precision than CTA. Agreement is also shown between literature values reported by CTA and those obtained by Taffit for HER on metal phosphide and selenide electrocatalysts. The Taffit algorithm substantially reduces subjectivity to improve the accuracy and precision of Tafel analysis.
 Tafel plot Tafel slope exchangecurrent density Taffit HER on glassy carbon electrode electrocatalysts Tafel analysis UIOWA OA Agreement

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