Inhibiting effect of acetonitrile on oxygen reduction on polycrystalline Pt electrode in sodium chloride solution

The oxygen reduction reaction (ORR) was studied on a polycrystalline Pt electrode in 0.1 M NaCl electrolyte 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 a polycrystalline Pt rotating disc electrode by linear sweep voltammetry in oxygen saturated electrolytes. The acetonitrile is chemisorbed on Pt over a wide potential range, inhibiting both hydrogen adsorption and oxide formation. The extent of AcN chemisorption depends on its concentration in the solution. The initial potential of oxygen reduction is shifted negatively, while the ORR current is increasingly reduced with the increase of AcN concentration. Complete inhibition of ORR in the potential range of AcN and Cl anion coadsorption is achieved for a 0.1 M NaCl + 1 M AcN solution