Formation of PtRu alloy nanoparticle catalyst by radiolytic process assisted by addition of dl-tartaric acid and its enhanced methanol oxidation activity

PtRu nanoparticle catalysts with 2-nm size supported on carbon were synthesized by a radiolytic process, assisted with the addition of dl-tartaric acid. Gradual alloying with the addition was confirmed by structural analyses with techniques of the X-ray diffraction and the X-ray absorption fine structure. Their methanol oxidation activities evaluated by the linear sweep voltammetry were higher than that of the commercial one, and found to be enhanced in accordance with the gradual change in the bimetallic structure from the Pt-core/Ru-shell to the random alloy. A good correlation was found between the catalytic activity and the indicators, which stands for the occurring frequency of the Pt-Ru bonds, calculated from the coordination numbers determined by the extended X-ray absorption fine structure analysis. It was confirmed that the addition of dl-tartaric acid in the radiolytic process certainly promoted the random alloy formation of PtRu bimetallic nanoparticles and enhanced their methanol oxidation activity.