The Alloying Effect on Anode Catalyst Activity

Due to the faeile poisoning effect of CO on Pt, many Pt-based binary alloys, such as Pt-Ru, Pt-Os, Pt-Sn, Pt-W, Pt-Mo, and so on, have been investigated as electrocatalysts for the methanol oxidation reaction (MOR) on flic DMFC anode. Among them, the Pt-Ru alloy has been found to be the most active binary alloy catalyst, and is commonly used in state-of-the-art DMFCs [32]. 

With a combination of advanced preparation methods and carbon supports, the currently used Pt-Ru/C catalysts could drive a state-of-the-art DMFC single eell with eurrent densities of 200-600 mA cm at a cell voltage of 400 mV, depending on the operating eonditions. For example, Guo et al. [35] recently reported that a eurrent density of 540 mA cm at 400 mV was observed in a Pt-Ru/C eatalyzed 

However, the power density of a DMFC using the state-of-the-art Pt-Ru/C anode catalyst is still a factor of 10 lower than that of a hydrogen-fuelled PEM fuel cell if the same noble metal loading is used. The efficiency of DMFCs operating on Pt-Ru alloy catalysts may yet be insufficient for practical application. Thus, much investigation has been done to improve the performance of the Pt-Ru binary catalysts by the incorporation of a third metal, such as W, Mo, Co, Ni, V, Pd, Rh, Sn, Os, or Ir. Some of these ternary Pt-Ru-M alloy catalysts show 

In addition, quaternary Pt-Ru-based alloys were also investigated as methanol oxidation catalysts for further improving the anode performanee in DMFCs. Some of the quaternary alloys, such as Pt-Ru-W-Sn [41], Pt-Ru-Os-Ir [42], Pt-Ru-W-Mo [43], Pt-Ru-Ni-Zr [44], and Pt-Ru-Ir-Sn [45], have been demonstrated to be more active than the state-of-the-art Pt-Ru catalyst towards the MOR. Due to a huge 

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