Molecular Oxygen Reduction Electrocatalyzed by <i>meso</i>-Substituted Cobalt Corroles Coated on Edge-Plane Pyrolytic Graphite Electrodes in Acidic Media

Abstract

Five <i>meso</i>-substituted cobalt­(III) corroles were examined as to their catalytic activity for the electoreduction of O₂ when coated on an edge-plane pyrolytic graphite electrode in 1.0 M HClO₄. The investigated compounds are represented as (T<i>p</i>RPCor)­Co­(PPh₃), where T<i>p</i>RPCor is the trianion of a <i>para</i>-substituted triphenylcorrole and R = OMe, Me, H, F, or Cl. Three electrochemical techniques, cyclic voltammetry, linear sweep voltammetry with a rotating disk electrode (RDE), and voltammetry at a rotating ring disk electrode (RRDE), were utilized to evaluate the catalytic activity of the corroles in the reduction of O₂. Cobalt corroles containing electron-withdrawing substituents were shown to be better catalysts than those having electron-donating groups on the three <i>meso</i>-phenyl rings of the triarylcorroles