Metal-Free Homogeneous O₂ Reduction by an Iminium-Based Electrocatalyst

The oxygen reduction reaction (ORR) is important for alternative energy and industrial oxidation processes. Herein, an iminium-based organoelectrocatalyst (im⁺) for the ORR with trifluoroacetic acid as a proton source in acetonitrile solution under both electrochemical and spectrochemical conditions using decamethylferrocene as a chemical reductant is reported. Under spectrochemical conditions, H₂O₂ is the primary reaction product, while under electrochemical conditions H₂O is produced. This difference in selectivity is attributed to the interception of the free superoxide intermediate under electrochemical conditions by the reduced catalyst, accessing an alternate inner-sphere pathway.