Effect of cadmium and lead adatoms on the reduction kinetics of peroxodisulfate anions at platinized platinum in acid solutions

The reduction of peroxodisulfate anions on a rotating Pt/Pt disk electrode in solutions of sulfuric and perchloric acids with or without cadmium and lead salts is studied. At E_r > 0.2V (RHE) the reduction rate in HClO₄ exceeds that in H₂SO₄, but at E_r < 0.2V, the process in HClO₄ is strongly inhibited upon approaching E_r = 0. Lead adatoms catalyze the process, while cadmium adatoms inhibit it in H₂SO₄ and accelerate it at E_r < 0.2V in HClO₄. The results are interpreted by taking account of the specific adsorption of sulfuric-acid anions and their co-adsorption with cadmium cations, as well as the adsorption of peroxodisulfate anions on the Pt surface modified by lead and cadmium ions in perchlorate solutions.Translated from Elektrokhimiya, Vol. 41, No. 2, 2005, pp. 137–141.Original Russian Text Copyright © 2005 by Nikiforova, Petrii.This revised version was published online in April 2005 with corrections to the article note and article title and cover date.