Oxygen Reduction on Polycrystalline Pt and Au Electrodes in Perchloric Acid Solution in the Presence of Acetonitrile

Abstract

Oxygen reduction reaction (ORR) was studied on polycrystalline Pt and Au electrodes in 0.1 M HClO(4) solutions containing various amounts of acetonitrile (AcN). The state of the electrode surface was characterized by cyclic voltammetry in oxygen free electrolytes, while ORR studies were performed on polycrystalline Pt and Au rotating disc electrodes by a linear sweep voltammetry in oxygen saturated electrolytes. Acetonitrile is chemisorbed on Pt over a wide potential range inhibiting both H adsorption and oxide formation. The extent of AcN chemisorption depends on its concentration in the solution. Initial potential of oxygen reduction is shifted negatively, while the kinetics of ORR is increasingly hindered with the increase of AcN concentration. Inhibiting effect of acetonitrile on ORR is pronounced on both Pt(poly) and Au(poly). Complete inhibition of ORR in the potential range of AcN chemisorptions is achieved for 0.1 M HClO(4) solution containing 1 M AcN on Au(poly) and 3 M AcN on Pt(poly).