A Carbon Electrode Functionalized by a Tricopper Cluster Complex: Overcoming Overpotential and Production of Hydrogen Peroxide in the Oxygen Reduction Reaction

A study of the oxygen reduction reaction (ORR) on a screen printed carbon electrode surface mediated by the tricopper cluster complex Cu 3 (7‐ N ‐Etppz(CH 2 OH)) dispersed on electrochemically reduced carbon black, where 7‐ N ‐Etppz(CH 2 OH) is the ligand 3,3′‐(6‐(hydroxymethyl)‐1,4‐diazepane‐1,4‐diyl)bis(1‐(4‐ethyl piperazin‐1‐yl)propan‐2‐ol), is described. Onset oxygen reduction potentials of about 0.92 V and about 0.77 V are observed at pH 13 and pH 7 vs. the reversible hydrogen electrode, which are comparable to the best values reported for any synthetic copper complex. Based on half‐wave potentials ( E 1/2 ), the corresponding overpotentials are about 0.42 V and about 0.68 V, respectively. Kinetic studies indicate that the trinuclear copper catalyst can accomplish the 4 e − reduction of O 2 efficiently and the ORR is accompanied by the production of only small amounts of H 2 O 2 . The involvement of the copper triad in the O 2 activation process is also verified.