Characterization of different Pt–Ru catalysts by X-ray diffraction and transmission electron microscopy

Abstract

Carbon-supported Pt–Ru (1:1)-catalysts have been synthesized by two reduction methods in an aqueous phase and in a third way in an organic solution and characterized in comparison to a commercial Pt–Ru/C catalyst purchased from E-TEK. X-ray diffraction and transmission electron microscopy were carried out on the different samples in the as-synthesized state and after heat-treatment at 500°C in nitrogen and air atmospheres respectively. Powder patterns of the different catalysts in the as-synthesized state reveal a fcc pattern with d values matching or close to platinum. No evidence of metallic Ru or any oxide phases was found. After heat-treatment in nitrogen Ru reflections occur in the synthesized catalyst samples, backing the supposition of separate platinum and ruthenium particles instead of a Pt–Ru alloy.