Defining the transfer coefficient in electrochemistry: An assessment (IUPAC Technical Report)

作者：Rolando Guidelli, Richard G. Compton, Juan M. Feliú, E. Gileadi, Jacek Lipkowski, Wolfgang Schmickler, Sergio Trasatti · 发表于：Pure and Applied Chemistry · 年份：2014 · DOI：10.1515/pac-2014-5026 · 被引用次数：528 · 研究领域：Electrochemical Analysis and Applications、Analytical Chemistry and Sensors、Chemical and Physical Properties in Aqueous Solutions

Abstract The transfer coefficient α is a quantity that is commonly employed in the kinetic investigation of electrode processes. In the 3 rd edition of the IUPAC Green Book, the cathodic transfer coefficient α c is defined as –( RT / nF )( d ln k c /d E ), where k c is the electroreduction rate constant, E is the applied potential, and R, T , and F have their usual significance. This definition is equivalent to the other, -( RT / nF )( d ln| j c |/d E ), where j c is the cathodic current density corrected for any changes in the reactant concentration at the electrode surface with respect to its bulk value. The anodic transfer coefficient α a is defined similarly, by simply replacing j c with the anodic current density j a and the minus sign with the plus sign. It is shown that this definition applies only to an electrode reaction that consists of a single elementary step involving the simultaneous uptake of n electrons from the electrode in the case of α c , or their release to the electrode in the case of α a . However, an elementary step involving the simultaneous release or uptake of more than one electron is regarded as highly improbable in view of the absolute rate theory of electron transfer of Marcus; the hardly satisfiable requirements for the occurrence of such an event are examined. Moreover, the majority of electrode reactions do not consist of a single elementary step; rather, they are multistep, multi-electron processes. The uncritical application of the above de...