Studies on the Reduction Mechanism of Oxygen on Ag/C Catalysts in Alkaline Solutions

Carbon-supported silver (Ag/C) catalysts with different Ag contents are prepared using the Ag (I) coordination polymer, [Ag(C7H6NO2)(C6H12N4)(H2O)]n. The mechanism and activity of the oxygen reduction reaction (ORR) on these Ag/C catalysts are investigated by the cyclic voltammetry and the rotating ring disk electrode (RRDE) in alkaline solutions. The test results indicate that, under the same Ag crystallite sizes, the activities increase with increasing Ag contents from 5 to 20 wt.% and the ORR proceeds by a four-electron pathway on Ag/C catalysts, but with decreasing Ag contents, the ORR is catalyzed via the four-electron pathway and the two-electron pathway simultaneously.