Defect locating: One-step to monodispersed CoFe2O4/rGO nanoparticles for oxygen reduction and oxygen evolution

In this work, monodispersed CoFe2O4/reduced graphene oxide (rGO) nanoparticles have been successfully synthetized in one step from Co(Ⅱ) acetylacetonate, Fe(Ⅲ) acetylacetonate, benzylamine and graphene oxide (GO). A facile solvent method was designed to skillfully integrate the crystal growth process of CoFe2O4, the reduction process of GO and their compound process. In synthesis process, large numbers of defects on GO thin layers were smartly used to disperse CoFe2O4 nanoparticles. The micromorphology and the distribution of as-prepared samples were identified via X-ray diffraction (XRD), transmission electron microscope (TEM) and element mapping spectra. Results showed that the monodispersed CoFe2O4 nanoparticles were uniformly coupled with rGO thin layers. Good performance for both oxygen reduction and oxygen evolution of as-prepared CoFe2O4/rGO (0.92 V onset potential for oxygen reduction and 1.59 V overpotential at 10 mA cm−2 for oxygen evolution, vs. RHE) were found during a series of electrochemical tests, which make it a promising bi-functional catalyst in the field of fuel cells and metal-air batteries.