Cinética eletroquímica: comparação de curvas de polarização teóricas com as curvas experimentais


The Butler and Volmer work contributions provided to electrochemistry are represented by the general
electrochemical kinetic equation, known as the Butler-Volmer equation. This equation relates the electric current resulting from a potential applied to a system in which a single reversible redox reaction occurs. The Butler-Volmer equation assumes that the charge transfer reaction is the determining step of the considered system, i.e., only an activation polarization occurs. This paper briefly describes the deduction of the Butler-Volmer equation and discusses its limitations. For the latter purpose, a polarization curve was obtained for the system H⁺/ H² and this curve was compared to the theoretical curve predicted by the Butler-Volmer equation. It is observed that the experimental polarization curve is significantly influenced by changes occurred both in the electrolyte at the vicinity of metal/electrolyte interface and at the metal surface, as well as by the occurrence of other types of polarition such as concentration polarization. Only for low overpotential values, the experimental curves were coincidental. This shows that numerical values of electrochemical parameters must be carefully obtained, particularly for the Tafel constants, because errors associated with these values can be very large

CARDOSO, Juliana Lopes; PANOSSIAN, Zehbour. Cinética eletroquímica: comparação de curvas de polarização teóricas com as curvas experimentais. In: CONGRESSO BRASILEIRO DE CORROSÃO, INTERCORR 2012, 32., 2012, Salvador. Anais… Salvador: ABRACO, 2012. 13p.

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