Porous MCo2O4 (M = Zn, Cu, Fe, Mn) as high efficient bi-functional catalysts for oxygen reduction and oxygen evolution reaction

Abstract

Abstract High-efficiency bi-functional electrocatalysts with long-term stability are critical to the development of many kinds of fuel cells, because that the performance of battery is limited by the slow kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). In this work, porous MCo2O4 (M = Zn, Cu, Fe, Mn) were prepared by hydrothermal method with NH4F and urea as surfactants. FeCo2O4with porous structure has more oxygen defects and the larger specific surface area than other MCo2O4 (M = Zn, Cu, Mn), and it not onlysupplies more active sites but also avails the transmission of electrolyte and O2 in the process of ORR and OER in 0.1 M KOH aqueous solution. Porous FeCo2O4 electrode material produces less intermediate H2O2, and its ORR is mainly controlled by a 4e− reaction path. Compared with commercial Pt/C, the prepared FeCo2O4 has comparable ORR activity and excellent OER activity. At the same time, the stability of FeCo2O4 to ORR is significantly higher than that of commercial Pt/C. The porous FeCo2O4 was prepared by facile synthesis procedure could be a potential promising bi-functional catalyst due to its high electrocatalytic activities and long-term stability for both the ORR and OER.