Oxygen reduction on Ag-MnO2/SWNT and Ag-MnO2/AB electrodes

Bifunctional catalysts (Ag-MnO2)/SWNT were prepared by using a simple chemical reduction route on single-walled carbon nanotubes (SWNT). Five weight percentage of Ag-MnO2 on SWNT was found to be the best loading in terms of current density. The (Ag-MnO2)/SWNT catalyst was characterized and the kinetics towards oxygen reduction reaction (ORR) was determined and compared with that of Ag-MnO2 on acetylene black (AB) catalyst. The number of exchanged electrons for the ORR was found to be close to four on both (Ag-MnO2)/SWNT and (Ag-MnO2)/AB. The kinetic rate constant of catalytic reaction for the two catalysts was of the same order. The zinc-air batteries with both catalysts were fabricated and examined. A stable discharge potential plateau appeared at approximately 1.2 and 1.1 V with discharge capacities 261 and 190 mAh/g, respectively. (C) 2005 Elsevier Ltd. All rights reserved.