Preparation and characterization of nano-sized Pt–Ru/C catalysts and their superior catalytic activities for methanol and ethanoloxidation

Abstract

Carbon-supported PtRu nanoparticles (Ru/Pt: 0.25) were prepared by three different methods; simultaneous reduction of PtCl₄ and RuCl₃ (catalyst I) and changing the reduction order of PtCl₄ and RuCl₃ (catalysts II and III) to enhance the performance of the anodic catalysts for methanol and ethanol oxidation. Structure, microstructure and surface characterizations of all the catalysts were carried out by X-ray diffraction (XRD), transmission electron microscopy (TEM) coupled with energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The results of the XRD analysis showed that all catalysts had a face-centered cubic (fcc) structure with different and smaller lattice parameters than that of pure platinum, showing that the Ru incorporates into the Pt fcc structure by different ratios in all the catalysts. The typical particle sizes of all catalysts were in the range of 2–3 nm. The most active and stable catalyst for methanol and ethanol oxidation is catalyst III, in which a large amount (more than 90%) of PtRu alloy formation was observed. It has been found that this catalyst is about 8.0 and 33.4 times more active at ∼0.60 V towards the methanol and ethanol oxidation reactions, respectively, compared to the commercial Pt catalyst.