Screening of a Pt-Ru-Co Focus Library

The diverse combinatorial screening described in the previous sections revealed active Pt-Ru-Co methanol oxidation catalysts, especially near Pt20Co6oRu2o. A second primary screening cycle (Fig. 11.8) focused on a more limited compositional space to isolate the active region in more detail. Figs. 11.15 and 11.16 show the design and the sampled compositional space of a Pt-Ru-Co ternary library. The design contains a pure Pt catalyst, Pt-Co binaries (row A), Pt-Ru binaries (column 1) 

4 New Ternary Fuel Cell Catalysts for DMFC Anodes 1 293 

High methanol oxidation activity is observed for Co-rich compositions that are similar to stoichiometries identified in the broad screening study (Fig. 11.17). Particular examples are Pt14Co63Ru23 or Pt18Co62Ru2o- 

In contrast, Pt18Co62Ru20 is an active composition on the Pt-rich side of the activity maximum. A similar stability evaluation reveals relatively stable behavior, as shown in Fig. 11.19. This composition is similar to the original catalyst identified during the broad screening study. Diffraction after screening is substantially similar to that before screening (Fig. 11.19b), and EDX data before and after screening indicate stability (Fig. 11.19 c). 

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