Tafel curvature analysis in electrocatalysis: theoretical foundations and microkinetic simulations
- 1Hubei Key Laboratory of Electrochemical Power Sources
- 2Wuhan University
Abstract
A curved Tafel plot records how an electrocatalytic interface changes its response to potential. Its shape contains the signatures of adsorption, interactions between adsorbates and redistribution of reaction flux, yet these signatures are often compressed into a few fitted slopes. Here we develop Tafel curvature analysis as a quantitative framework for interpreting these transitions. Analytical adsorption theory and reversible microkinetic simulations connect the second derivative of logarithmic current to surface-response identities and experimentally testable features. For a turnover law with a constant explicit potential sensitivity, curvature eliminates both the current prefactor and the linear activation term. Ideal Langmuir adsorption then gives a direct susceptibility relation, a fixed amplitude–width relation and a signed-area sum rule. Competitive adsorption extends this result to a weighted squared response of the entire population vector. Lateral interactions reshape this response and produce a precisely located splitting transition: in the pair-dependent Frumkin model, two curvature peaks emerge above a repulsion parameter of 4/3 even though the surface has a single adsorbate population. Parallel currents generate a complementary positive contribution equal to the variance of their local slopes. These relationships organize the behavior of three catalytic networks. Hydrogen oxidation separates population response from pathway redistribution. CO oxidation predicts an activity-dependent curvature-peak displacement and exposes the kinetic influence of a sparsely occupied intermediate through its product-exit probability. For a four-state oxygen-reduction cycle, an exact decomposition links curvature to reversible driving, population motion and dispersion among elementary-rate products; a shared potential factor explains the zero-curvature limit. Together, the models show how curvature sign, area, width and peak motion characterize kinetic transitions and guide the choice of concentration and spectroscopic measurements. A synthetic measurement study further demonstrates recovery of single and split curvature features from discrete noisy currents by local polynomial regression, with propagated uncertainty and an explicit resolution–noise tradeoff. Tafel curvature thus turns variation in kinetic sensitivity into a set of quantitative physical relationships and practical tests of electrocatalytic surface dynamics.
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BibTeX
@misc{zhuang2026tafel,
title = {{Tafel curvature analysis in electrocatalysis: theoretical foundations and microkinetic simulations}},
author = {Lin Zhuang},
howpublished = {ChemRxiv},
year = {2026},
month = sep,
doi = {10.26434/chemrxiv.15009586/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009586/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Tafel curvature analysis in electrocatalysis: theoretical foundations and microkinetic simulations
AU - Lin Zhuang
PY - 2026
DA - 2026/09/28
PB - ChemRxiv
DO - 10.26434/chemrxiv.15009586/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009586/v1
AB - A curved Tafel plot records how an electrocatalytic interface changes its response to potential. Its shape contains the signatures of adsorption, interactions between adsorbates and redistribution of reaction flux, yet these signatures are often compressed into a few fitted slopes. Here we develop Tafel curvature analysis as a quantitative framework for interpreting these transitions. Analytical adsorption theory and reversible microkinetic simulations connect the second derivative of logarithmic current to surface-response identities and experimentally testable features. For a turnover law with a constant explicit potential sensitivity, curvature eliminates both the current prefactor and the linear activation term. Ideal Langmuir adsorption then gives a direct susceptibility relation, a fixed amplitude–width relation and a signed-area sum rule. Competitive adsorption extends this result to a weighted squared response of the entire population vector. Lateral interactions reshape this response and produce a precisely located splitting transition: in the pair-dependent Frumkin model, two curvature peaks emerge above a repulsion parameter of 4/3 even though the surface has a single adsorbate population. Parallel currents generate a complementary positive contribution equal to the variance of their local slopes. These relationships organize the behavior of three catalytic networks. Hydrogen oxidation separates population response from pathway redistribution. CO oxidation predicts an activity-dependent curvature-peak displacement and exposes the kinetic influence of a sparsely occupied intermediate through its product-exit probability. For a four-state oxygen-reduction cycle, an exact decomposition links curvature to reversible driving, population motion and dispersion among elementary-rate products; a shared potential factor explains the zero-curvature limit. Together, the models show how curvature sign, area, width and peak motion characterize kinetic transitions and guide the choice of concentration and spectroscopic measurements. A synthetic measurement study further demonstrates recovery of single and split curvature features from discrete noisy currents by local polynomial regression, with propagated uncertainty and an explicit resolution–noise tradeoff. Tafel curvature thus turns variation in kinetic sensitivity into a set of quantitative physical relationships and practical tests of electrocatalytic surface dynamics.
ER -