Electroreduction of peroxodisulfate anion at a Cd(0001) single-crystal plane electrode

Electroreduction of peroxodisulfate anion on an electrochemically polished Cd(0001) plane in aqueous NaF solution with different additions of Na2S2O8 was studied by rotating disc voltammetry. The rate of electroreduction of S2O2−8 depends on the electrode potential and base electrolyte concentration, i.e. on the thickness of the diffuse layer. The kinetic current densities at E=const have been obtained by the Koutecký–Levich method and used for the determination of the apparent rate constant values of electroreduction of S2O82− anion. The ψ0 potential values obtained according to the Gouy–Chapman–Grahame (GCG) model have been used for the construction of corrected Tafel plots, which were linear at E−ψ0<−1.1 V (SCE). The value of the charge transfer coefficient α decreases somewhat with the concentration of the base electrolyte solution (0.18≤α≤0.22), but the value of α is practically independent of the concentration of S2O82− ions if cNaF=const.