▎ 摘　　要

Reduced graphene sheets (RGSs) were prepared via chemical reduction of graphite oxide and their morphology was characterized by atomic force microscopy. The electrochemical reduction of oxygen (O-2) was RGSs was studied by cyclic, rotating disk electrode, and rotating ring-disk electrode voltammetry using the RGSs-modified glassy carbon (RGSs/GC) electrode in 3.5% NaCl solution. The results show that O-2 reduction undergoes three steps at the RGSs/GC electrode: electrochemical reduction of O-2 to H2O2 mediated by quinone-like groups on the RGSs surface, a direct 2-electron reduction of O-2, and reduction of the H2O2 produced to H2O. The modification of RGSs results in an obvious positive shift of the peak potential and a larger current density. The kinetics study shows that the number of electrons transferred for O-2 reduction can reach to 3.0 at pontentials of the first reduction step, indicating RGSs can effectively catalyze the disproportionation of H2O2. Such catalytic activity of RGSs enables a 4-electron reduction of O-2 at a relatively low overpontential in neutral media. RGSs are a pontential electrode material for microbial fuel cells. (C) 2010 Elsevier B.V. All rights reserved.