Gurney-Butler

It is important to note that as early as 1931, the density of electronic states in metals, the distribution of electronic states of ions in solution, and the effect of adsorption of species on metal electrode surfaces on activation barriers were adequately taken into account in the seminal Gurney-Butler nonquadratic quantum mechanical treatments, which provide excellent agreement with the observed current-overpotential dependence. 

R. Parsons and J. O M. Bockris, Trans. Faraday Soc. 47 914 (1951). Gurney-Butler approach applied quantitatively to proton discharge (numerical). 

Extension of the Gurney-Butler treatments of the kinetics of electrochemical charge-transfer was made in terms of the "transition-state" theory of Eyring, Glasstone and Laidler in a paper (27) by... 

Attempts were made to quantitatively treat the elementary process in electrode reactions since the 1920s by J. A. V. Butler (the transfer of a metal ion from the solution into a metal lattice) and by J. Horiuti and M. Polanyi (the reduction of the oxonium ion with formation of a hydrogen atom adsorbed on the electrode). In its initial form, the theory of the elementary process of electron transfer was presented by R. Gurney, J. B. E. Randles, and H. Gerischer. Fundamental work on electron transfer in polar media, namely, in a homogeneous redox reaction as well as in the elementary step in the electrode reaction was made by R. A. Marcus (Nobel Prize for Chemistry, 1992), R. R. Dogonadze, and V. G. Levich. 

There is no doubt that this field, like few others, owes very much to its founder, Ronald Gurney, because of the fast start he gave it by applying quantum mechanics to interfacial electron transfers shortly after the publication of Schrodinger s wave equation (1926). The early seminal contributions (to which must be added that of J. A. V. Butler in the same period)22 founded quantum electrochemistry and led to its broader development by Gcrischer (1960), in particular the idea of the absolute scale of potentials and the equation... 

Figure 1. Potential energy profile diagrams for a charge transfer process as in ion discharge with coupled atom transfer (based on representations by Gurney and Butler L In (b), curve / represents the H /H20 proton interaction potential and m that for discharged H with the metal M. R is the repulsive interaction of H with H2O and A the resultant interaction curve for H with M.

In the original treatment of Gurney/ the current was expressed as the integral of the product of electrolyte and electron energy distribution functions but with the electronic one written as a Boltzmann factor, exp( A /fcT). The symmetry factor was introduced intuitively in terms of the shift of intersection point of energy profiles in relation to change of electrode potential, i.e., of the Fermi-level energy (cf. Butler ). 

The quantum mechanical theory of electrode kinetics has been developed in recent time in two entirely different ways. One is the molecular and mechanistic theory orginated by Gurney as early as 1931. This molecular approach was further developed by Butler/ Gerischer/ Christov/ Bockris et Schmickler/ " and Khan et The other is the... 

An important contribution was made by Butler in 1936. Butler realized that the theory of Gurney did not give reasonable values of the heat of activation, and realized the essential reason, namely, that Gurney did not... 

We know that thermodynamics is a very powerful tool for the study of systems at equilibrium, but electrode processes are systems not at equilibrium when at equilibrium there is no net flow of current and no net reaction. Therefore electrode reactions should be studied using the concepts and formalities of kinetics. Indeed, the same period that saw the flourishing of solution electrochemistry, also saw the formulation of the fundamental theoretical concepts of electrode kinetics the work of Tafel on the relationship of current and potential was published in 1905 those of Butler and Volmer and Erdey Gruz, which formulated the basic equation for electrode kinetics, were published in 1924 and 1930 respectively. Frumkin in 1933 showed the correlation between the structure of the double layer and the kinetics of the electrode process. The first quantum mechanical approach to electrode kinetics was published by Gurney in 1931. 

During several years after the publication of the works of Gurney and Horiuti and Polanyi, some articles appeared in which the authors developed and combined to a certain extent these two approaches. Among these articles, we should first mention those by Butler[185] and Essin[186]. Further studies carried out during several years were mainly aimed at refining model calculations within the framework of the Horiuti-Polanyi theory ([135,187], and subsequent works, for example [31,44,188,189]). 

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