Mesoporous nanostructured spinel-type MFe2O4 (M=Co, Mn, Ni) oxides as efficient bi-functional electrocatalysts towards oxygen reduction and oxygen evolution

Development of excellent bi-functional electrocatalysts for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) remains a key issue for the commercialization of various electrochemical devices such as fuel cells and metal-air batteries. Herein, we report the synthesis and electrocatalytic performance of mesoporous nanostructured spinel-type MFe2O4 (M=Co, Mn, Ni) oxides which can serve as alternative low-cost bi-functional electrocatalysts for ORR/OER. Loaded on XC-72 carbon support, the MFe2O4 spinel oxides show the M-dependent catalytic activities with CoFe2O4 being the most active electrocatalyst followed by MnFe2O4 and NiFe2O4 for ORR. For the OER, however, the activity increases in the order: MnFe2O4