▎ 摘　　要

Due to the important applications in metal-air batteries and in the photo- electrochemical catalytic decomposition of organics, the electron transfer number (n) of the oxygen reduction reaction (ORR) on N-doped reduced-graphene oxide (N-RGO) is precisely controlled and predicted by combining the studies of factorial design (FD) and the path of the steepest ascent/descent (PSA/PSD). Here, n is selected as the response variable to make the ORR undergo either the two-electron or four-electron transfer mechanism. Based on the FD study, n is mainly determined by microwave power and N-doping temperature. By varying the above two factors simultaneously, n of the ORR varying from ca. 2.6 to 3.8 can be precisely controlled. In the X-ray photoelectron spectroscopic (XPS) analysis, the pyrrolic-nitrogen structure has been confirmed to be the main nitrogen structure affecting the selectivity of the ORR. The N-RGO preferring to the two-electron ORR process can be used to generate H2O2 for photo-electrochemical catalytic degradation of organics. The N-RGO with n of the ORR close to 4 will be employed in the aqueous metal-air batteries. (C) 2013 The Electrochemical Society. All rights reserved.