Electrochemical Reduction of Oxygen Using a Metal–Organic Complex of Cu^2+ †

A biphenyl-based copper complex was evaluated as electrocatalyst for the oxygen reduction reaction (orr), for a possible application as cathode material in fuel cells. To carry out this evaluation, the complex was supported on Vulcan carbon and deposited as a film on a glassy carbon rotating disk electrode by drop-casting a 1-μL drop of a suspension of carbon in a solution of the complex in dimethyl sulfoxide containing Nafion as ionic conductive binder, and drying under vacuum. The cyclic voltammogram in 0.1 M NaOH solution showed voltammetric peaks between 0.8 and 1.0 V vs. reference hydrogen electrode, which suggest the existence of electron transfer processes from/toward the ligand. The orr was tested in oxygen-saturated (1 atm) solution by linear sweep voltammetry, which showed significant orr current at relatively low overpotential (around −0.4 V), demonstrating the ability of the complex to electrocatalyze the orr efficiently.