Effect of the Oxide–Carbon Heterointerface on the Activity of Co3O4/NRGO Nanocomposites toward ORR and OER

Abstract

This work reports the synthesis of Co 3 O 4 particles that can be used as effective electrode materials for both the oxygen reduction (ORR) and evolution (OER) reactions. The development of such catalysts, free from precious group metals and capable of decreasing overpotentials in fuel cells, metal–air batteries, and water electrolyzers, also requires stable supporting and conducting substrates in order to deposit low metal oxide loadings. This challenging approach led us to prepare Co 3 O 4 materials on graphene-based composites more stable than common used Vulcan carbon. Co 3 O 4 particles synthesized from a solvothermal method were thereby deposited onto reduced graphene oxide (RGO) and N-doped reduced graphene oxide (NRGO) prepared from the Hummers method. The structural properties and surface composition of the different materials characterized by X-ray diffraction, transmission electron microscopy, and X-ray induced photoelectron spectroscopy measurements were combined to cyclic voltammetry experiments for revealing the charge transfer from cobalt to nitrogen, which greatly affects the charge acceptance of the surface Co atoms. Electrochemical measurements provided sound evidence of active and stable Co 3 O 4 catalysts toward the ORR and OER.