Oxygen electroreduction on polycrystalline gold electrodes and on gold nanoparticle-modified glassy carbon electrodes

The oxygen reduction reaction (ORR) in acid media can be catalyzed on gold electrodes when the surface is activated by mechanical or electrochemical pretreatments. The activation is caused by increased surface roughness and defects, or asperities. After activation, a slow recrystallization of the surface as a function of relaxation time leads to deactivation of the surface for the ORR. After removal of active centers, the surface is not affected over time, which reveals that the surface recrystallization is associated with the deactivation. Experiments using various amounts of Au nanoparticles (AuNPs) immobilized on glassy carbon (GC) show a positive shift of peak potential of oxygen reduction and peroxide oxidation with increasing particle coverage.