The answer is not easy, because you need choose between physical or chemical methods for preparation of AU-Pd Catalyst, also depending of the kind of segragation between the Au and Pd, maybe you like obtain a core shell alloys or Janus particles, I suggest that visit and read the next links:
If you are interested in making alloy-type particles, you can consult the recent paper of Adzic and co-workers: Angew. Chemie. Int. Ed. 2010, 49, 8602-8607. We have also developed a simple process for making NWs of this composition.