Enhanced electrocatalytic activity of oxygen reduction by cobalt-porphyrin functionalized with graphene oxide in an alkaline solution

Cobalt[5,15-(p-aminophenyl)-10,20-(pentafluorophenyl)porphyrin] (CoAPFP) functionalized with graphene oxide (GO) by N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC hydrochloride) was used as an amide-coupling reagent (GO-CoAPFP). Electrochemical investigation revealed that ERGO-CoAPFP exhibited much better catalysis and better-improved oxygen reduction reaction (ORR) than GO-CoAPFP. ERGO-CoAPFP is a simple and facile method of improving electrocatalytic activity. The ERGO-CoAPFP catalysts were tested in ORR using electrochemical techniques such as cyclic voltammetry (CV) and rotating-ring-disk-electrode (RRDE) hydrodynamic voltammetry to quantitatively obtain the ORR kinetic constants and the reaction mechanisms on a glassy carbon electrode (GCE) in a 0.1 M KOH solution. The electrocatalytic oxygen reduction reaction of RRDE modified with ERGO-CoAPFP established a pathway of four-electron transfer reactions.