The activities of a series of carbon-supported bimetallic catalysts, with different active phases loadings, were tested towards the oxygen reduction reaction (ORR). Pt was used in all materials and its loading was kept constant. Mo, W and Ru were used as promoting phases. Rotating Disk electrode experiments revealed that Pt-Ru displayed the best performance in oxygen reduction among the studied materials. The materials with the highest loadings of the second metal revealed the highest activities. X-Ray Diffraction studies (XRD) and Transmission Electron Microscopy (TEM) revealed the presence of homogeneously dispersed metallic ruthenium and different tungsten or molybdenum oxides in the corresponding catalysts. No evidence of alloying was found, and thus the catalytic performances appear to be related to the distribution and interaction of the active phases.

Different carbon-supported Pt-Mo and Pt-Ru materials were synthesized and a systematic study was carried out in order to evaluate their catalytic activity towards methanol oxidation. Direct current methods were applied in sulfuric acid and methanol - containing electrolytes, in order to evaluate the electrochemical response of the studied electrodes. Pt-Mo catalysts reveal similar performances and, in some cases, higher than Pt-Ru materials. For both catalysts series, it was found that low loadings of the promoting metal (Ru or Mo) improve the methanol oxidation activity. Characterizations by means of transmission electron microscopy and X-Ray Diffraction allowed to measure mean particle sizes below 10 nm for all phases. The Pt-Ru catalysts consist of metallic Pt and metallic ruthenium, while in the The Pt-Mo materials platinum is present in its metallic state and MoO3 is the predominant molybdenum species.