Oxygen reduction to hydrogen peroxide on Fe3O4 nanoparticles supported on Printex carbon and Graphene

Abstract

Fe3O4 nanoparticles supported on graphene (Fe3O4/graphene) and Printex carbon (Fe3O4/Printex) are reported as promising catalysts for oxygen reduction reaction (ORR) to H2O2 in alkaline medium. The catalysts were synthesized by a simple precipitation method using NaBH4 as reducing agent to favor the formation of the magnetite phase. The structure and morphology of the catalysts was evaluated by x-ray diffraction, transmission electron microscopy and small angle electron diffraction. The electrocatalytic activity towards ORR was investigated by means of cyclic and linear voltammetries in 1molL−1 KOH. The linear polarization curves highlighted the synergetic effect between the oxide and the carbon supports. Analysis of the polarization curves showed that electro-catalytic activity of the materials towards oxygen reduction expressed by the current density at −0.3V vs SCE increases from Printex (0.29mAcm−2)<Fe3O4/Printex (0.38mAcm−2)<graphene (0.85mAcm−2)<Fe3O4/graphene (1.12mAcm−2). The number of exchanged electrons was close to 2.7 for both catalysts, and the % H2O2 electro-generated above 60% in the −0.2 to −0.7V (vs SCE) potential range. Furthermore, both Fe3O4/graphene and Fe3O4/Printex catalysts show excellent durability.