Anomalous temperature dependence of the hydrogen evolution reaction on iron

Cathodic polarizations for the hydrogen evolution reaction on Armco iron in perchloric acid measured in the temperature range 278 −348 K and pH range 0.5–2.0 follow the Tafel relationship but with anomalous temperature dependence. Instead of varying widely with temperature, the measured values of th...

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Bibliographic Details
Published in:Journal of electroanalytical chemistry and interfacial electrochemistry 1989-06, Vol.265 (1), p.171-178
Main Authors: VRACAR, L. M, DRAZIC, D. M
Format: Article
Language:English
Subjects:
Adsorption
Chemistry
Electrochemistry
Electrodeposition
Exact sciences and technology
General and physical chemistry
Study of interfaces
Transport phenomena
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Summary:Cathodic polarizations for the hydrogen evolution reaction on Armco iron in perchloric acid measured in the temperature range 278 −348 K and pH range 0.5–2.0 follow the Tafel relationship but with anomalous temperature dependence. Instead of varying widely with temperature, the measured values of the slope were between 115 and 140 mV dec −1, i.e., ±10%. This is ascribed to an anomalous change of the apparent transfer coefficient α c with temperature. Various possible reasons for this behaviour, such as adsorption and absorption of hydrogen, mechanism change and impurity effects, are ruled out on the grounds of experimental findings, leading to changes in the symmetry factor, β, as the probable reason. Following the Conway approach, numerical values of the enthalpic and entropic part of the symmetry factor are evaluated.
ISSN:0022-0728
DOI:10.1016/0022-0728(89)80187-1