Nanoparticles of Fe2O3 and Co3O4 as efficient electrocatalysts for oxygen reduction reaction in acid medium

Abstract

This paper presents a comparative study about the oxygen reduction reaction (ORR) catalyzed by nanoparticles of Fe2O3 and Co3O4 applied on the surface of glassy carbon electrodes (GCE). The nanoparticles were synthesized using the modified polymeric precursor method (Pechini). These two nanomaterials were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) techniques. The estimated average particle sizes were 21 and 31 nm for Fe2O3 and Co3O4, respectively. Electrochemical impedance spectroscopy (EIS) showed that Fe2O3/GCE has lower charge transfer resistance than Co3O4/GCE. The surface electrochemistry of both Fe2O3/GCE and Co3O4/GCE was studied in the solution free of O2, and their corresponding reaction mechanisms were analyzed. The electrocatalytic ORR activities of these two catalysts were studied by cyclic voltammetry (CV) and rotating disk electrode (RDE) in acidic solution. The results obtained by RDE indicated that both Fe2O3/GCE and Co3O4/GCE can catalyze the ORR with a dominating 2-electron transfer process to produce H2O2, using a potential of −0.8 V. These kinetic results indicate that Fe2O3/GCE is more efficient than Co3O4/GCE in terms of ORR. Considering the low cost of these two non-noble metal catalysts, they may be used as viable alternatives for ORR electrocatalysts.