Oxygen reduction reaction kinetics on pure copper in neutral sodium sulfate solution

Abstract

Oxygen reduction reaction (ORR) kinetics were investigated on different copper surface conditions in 10 – 2 M Na2SO4 solution. On pre-reduced and passivated copper surfaces, the ORR is suggested to occur by a parallel pathway involving HO2− formation followed by its diffusion to the solution or rapid reduction to OH−. A significant difference in ORR activity is observed in the kinetic and mixed control regions as copper surface becomes more oxidized. On a surface covered by ammonium pyrrolidine dithiocarbamate (PDTC), ORR rate is inhibited due to the adsorption of PDTC and formation of a protective film, which limits O2 deposition on copper surface regardless of pH values and oxygen concentration in the solution.