▎ 摘　　要

Development of an oxygen electrode with high stability and good electrochemical activity is critical to achieve the practical applications of rechargeable lithium-oxygen batteries (LOBs) in our daily life. here, we report the facile synthesis of a graphene-based composite as an efficient dual function precious metal-free electrocatalyst for LOBs by applying graphite oxide as the graphene precursor, aniline as the carbon and nitrogen source, FeCl3 and Co(NO3)(2)center dot 6H(2)O as the cation sources and argon as the atmosphere during the pyrolysis. Scanning electron microscope and transmission electron microscope observations demonstrate that the as-prepared electrocatalyst is composed of graphene sheets with nanoparticles mainly in the size of 20-50 nm, while X-ray diffraction characterization confirms that the sample is composed of multiple species such as carbon, cobalt/iron oxide, cobalt/iron sulfide and metallic iron. The cyclic voltammetry and linear sweep voltammograms tests of the electrocatalyst demonstrate favorable electrocatalytic activity for both oxygen reduction and evolution reactions, suggesting its bifunctionality. With the electrocatalyst/Ketjen Black (KB) oxygen electrode applying in LOBs, a specific capacity of 4772 mAh g(KB)(-1) and a discharge plateau potential of similar to 2.75 V are reached at the density of 100 mA gKB(-1) for the related LOBs by discharging to 2.0 V and charging to 4.4 V. (C) 2015 Elsevier Ltd. All rights reserved.