New PtRu Alloy Colloids as Precursors for Fuel Cell Catalysts

We describe the preparation and characterization of new PtRu alloy colloids that are suitable as precursors for fuel cell catalysts. The new, simplified preparation method, which uses an organometallic compound both for reduction and as colloid stabilizer, leads to a PtRu colloid possessing lipophilic surfactant stabilizers. These can easily be modified to show hydrophilic properties. Prior to electrochemical measurements the surfactant shell is removed by reactive annealing in O2 and H2. Comparing the electrocatalytical activity of the Vulcan-supported colloids with that of a differently prepared PtRu colloid investigated recently and with a commercially available PtRu catalyst, we found practically identical activities with respect to CO and CO/H2 oxidation. Activities of similar order of magnitude were found also for methanol oxidation. The results demonstrate the high potential of the new, organometallic preparation scheme for the synthesis of colloid precursors for bimetallic catalysts, especially if it is considered that variations in the alloy composition can easily be realized using the colloidal preparation method.