Hydrogen Peroxide Oxidation/Reduction Reaction on Platinum Surfaces

Abstract

Hydrogen Peroxide oxidation or reduction reactions are key processes for many reactions with practical purpose. In electrochemical systems, the processes can be switched by each other depending on the electrode potential, causing important implications on oxygen reduction reaction. Herein the reactions are analyzed in term of Pt surface orientation in nonadsorbing anions electrolytes. Considering the oxidation and reduction branches as independent contributions limited by mass-transfer, E1/2 can be fitted for each process in both acid and alkaline media. E1/2 analysis reveals that in acid media stepped surfaces are more catalytic than basal planes for both oxidation and reduction processes; however Pt(111) in alkaline media tends to be the best and worst catalyst the reduction and oxidation processes, respectively, when compared with other planes. On oxidized surfaces, regardless the electrolyte pH, Pt(111) becomes the best catalyst to the H2O2 reduction reaction and the worst to the oxidation. Finally, the analysis of Pt(111) oxidation dynamic allows to conclude the H2O2 oxidation occurs in the presence of both PtOH and PtO, but in the last case, it is expected more than one reaction mechanism, probably involving a coupled chemical and electrochemical step.