IrxCo1−x (x = 0.3–1.0) alloy electrocatalysts, catalytic activities, and methanol tolerance in oxygen reduction reaction

Novel methanol-tolerant catalysts for oxygen reduction reaction (ORR), IrxCo1−x/C (x = 0.3–1.0), were synthesized by a conventional impregnation method. These carbon-supported catalysts showed particle sizes of 2.7–5.0 nm. The catalyst activity and the catalyzed ORR kinetics were characterized by cyclic voltammetry and rotating disk electrode methods. Among these IrxCo1−x/C catalysts, the alloy with a formula of IrxCo1−x/C with x value in the range of 0.7–0.8 exhibited the highest mass and specific activities. Compared to a Pt/C catalyst, these alloy catalysts have much stronger methanol tolerance in terms of ORR onset potential (or open-circuit potential). Based on the rotating disk electrode measurements, it was confirmed that these IrxCo1−x/C alloy catalysts could catalyze a complete four-electron transfer reaction of oxygen to water. These results strongly suggest that the novel Ir–Co metal alloy catalysts synthesized in this work could be promising for DMFC cathodes.