Voltammetry of surface electrodimerization processes.: Application to the oxidation of adsorbed 2-mercaptoethyl ether on mercury

The theory for surface dimerization reactions under linear voltammetric conditions, and in the absence of mass transport complications, has been extended to remove the kinetic constraints of previous treatments. The solution of the initial value problem is shown to be identical when reactant and products remain in the adsorbed state and when the adsorbed reactant is allowed to equilibrate with its bulk concentration at any potential. Analytical expressions for the voltammetric waves are derived for some kinetic limits of interest, and empirical equations are developed to relate the peak coordinates and wave width with experimental variables when only numerical solutions are available. Theoretical predictions are applied do the analysis of the oxidation of adsorbed 2-mercaptoethyl ether on mercury, which is shown to consist of a monoelectronic exchange followed by a fast reversible dimerization.