Spinel-type CoFe2O4 embedded in N-doped Porous Hollow Carbon Sphere as a Highly Efficient Electrocatalyst for Oxygen Reduction Reaction

초록

Oxygen reduction reaction (ORR) plays a critical role in electrochemical energy conversion and storage devices such as fuel cells and metal-air batteries. However, the efficiency of the devices and commercialization are hindered by the sluggish ORR kinetics [1,2]. Consequently, developing efficient and non-precious metal-based electrocatalysts is of great importance for promoting their practical application [3]. Among a wide variety of transition metal oxides, bimetal spinel oxides (AB2O4, A, B = Ni, Co, Fe, and Cu) have attracted great attention because of their low cost, structural stability, and earth abundance [1]. In this study, N-doped porous hollow carbon sphere coated with CoFe2O4 spinel structure (CoFe2O4-NPHCS) was synthesized by pyrolysis and high-temperature carbonization with melamine-formaldehyde resin sphere as self-sacrifice templates and dopamine as N and C sources. Benefitting from the large specific surface area, porous hollow structure, high content of N dopants, CoFe2O4-NPHCS exhibits highly efficient catalytic activity and long-term stability for ORR in an alkaline solution comparable to state-of-the-art Pt/C. This work can provide a new synthetic method for designing highly efficient, cost-effective electrocatalysts for ORR.