Methanol oxidation catalysis and substructure of PtRu bimetallic nanoparticles

Abstract

Abstract Catalytic material of PtRu nanoparticles supported on carbon (PtRu/C) for direct methanol fuel cells was synthesized by a polyol reduction method. Addition of phosphorus was effective for downsizing PtRu particles and improving their catalytic activity. The activity obtained was six times of that of a commercial catalysis. The samples were analyzed by techniques of X-ray absorption fine structure (XAFS) at Pt L III -edge and Ru K-edge, transmission electron microscope (TEM), X-ray diffraction (XRD) and X-ray fluorescence (XRF). These results indicated a core–shell structure consisting of a Pt-rich core and Ru-rich shell. By examining coordination numbers determined by XAFS analysis, we found a clear correlation between the catalytic activity and the Pt–Ru atomic pair frequency occurring on the particle surface, which supports the “bi-functional mechanism”.