An extraordinary electrocatalytic reduction of oxygen on gold nanoparticles-electrodeposited gold electrodes

The cathodic reduction of oxygen has been investigated at a gold nanoparticles-electrodeposited gold electrode in 0.5 M H2SO4 solution. Two well-defined reduction peaks were observed at +50 and -250 mV vs. Ag/AgCl/KCl (sat.). Those two peaks indicated a 2-step 4-electron reduction pathway of O2 in this strong acidic medium. The former peak was ascribable to the 2-electron reduction of O2 to H2O2, while the latter was assigned to the reduction of H2O2 to H2O. The observed electrocatalysis for the reduction of O2 is attributable to the extraordinary catalytic activity of the gold nanoparticles over the bulk gold electrode, at which the 2-electron reduction peak of O2 to H2O2 was observed at -200 mV. © 2002 Elsevier Science B.V. All rights reserved.