One-pot Synthesized Co/Co3O4-N-Graphene Composite as Electrocatalyst for Oxygen Reduction Reaction and Oxygen Evolution Reaction

Efficient bifunctional catalysts for reversible oxygen electrodes, for electrocatalysis of both the oxygen reduction reaction (ORR) and the oxygen evolution reactions (OER) are envisioned to make a significant contribution towards the need for environmentally friendly and renewable energy systems. Despite tremendous efforts, there is still need for further development of bifunctional catalysts to achieve low-cost catalysts with stable satisfactory long-term performance, enhanced kinetics of the ORR and OER and high round-trip electrolytic-galvanic mode voltage efficiency. Herein, we demonstrate a simple one-pot procedure for synthesis of a bifunctional catalyst comprised of a composite of cobalt/cobalt oxide and N-doped graphene (denoted as Co/Co3O4-N-graphene), which exhibits very good performance in the electrocatalysis of both ORR and OER in alkaline solution. The prepared composite was characterized by TEM, SEM, Raman, XRD and XPS, to give insight of its structure-performance correlation. The results reveal that the structure of N-doped graphene is preserved and that both metallic Co and its oxide form of Co3O4 co-existed in the prepared composite, with metallic Co being predominant crystalline component. Generally, a high ratio of Co in the prepared composite led to improvement of the onset potential for the OER.