Preparation and characterization of platinum-ruthenium bimetallic nanoparticles using reverse microemulsions for fuel cell catalyst.

Platinum-ruthenium bimetallic nanoparticles are prepared by chemical reduction using sodium borohydride in reverse microemulsions of water/isooctane/Igepal CA-630/2-propanol for fuel cell catalysts. The prepared nanoparticles are characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and energy-dispersive X-ray analysis. The average size and morphology of nanoparticles are dependent on the water volume fraction in reverse microemulsion system in the range of ca. 2-4 nm. The morphology of particles is related with the percolation behavior of water droplets in reverse microemulsions. By the pretreatment of water phase using a hydrochloric acid, the particles of a homogeneous solid solution state can be obtained. The CO stripping cyclovoltammetry and the electrochemical measurements compared with commercial catalyst show that the prepared particles have a high electrochemically active surface area and a stable and high catalytic activity for reformate gas oxidation.