Graphene-Supported Cobalt(III) Complex of a Tetraamidomacrocyclic Ligand for Oxygen Reduction Reaction

Abstract

Polymer electrolyte membrane fuel cells (PEMFCs) are at the cusp of providing large scale energy solutions, yet challenges in developing high performance, durable, and cost effective platinum catalyst alternatives continue to impede commercialization efforts. A graphene-supported cobalt(III) catalyst nanocomposite was prepared and investigated for the first time as a potential cathode material for PEMFCs. The material was characterized using a variety of microscopy and spectroscopy techniques, and the electrochemical performance was assessed using voltammetry equipment. A peak potential at − 0.088 V versus standard hydrogen electrode was observed by cyclic voltammetry during oxygen reduction reaction (ORR). The material was found to reduce oxygen via a four-electron process in both acidic and alkaline pH conditions, with rotating disk electrode and rotating ring disk electrode studies revealing the ORR to occur via 3.60 and 3.86 electrons at pH 2, respectively. A rate constant of 9.78 × 106 mol− 1 s− 1 was observed for the cobalt(III) catalyst/graphene complex in acidic conditions, and a mechanism has been proposed based on these results. An economic, non-precious cobalt(III) complex supported on graphene successfully reduced oxygen at a high rate in cathodic fuel cell applications.