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A type of small electrode for basic studies on metal alloy powder materials for metal-hydride anodes has been proposed. The electrode holds a few milligrams of the active material and contains no inert binder material admixed to the active material. The electrode is prepared simply in a laboratory mechanical press. It was shown using cyclic voltammetry and electrochemical impedance spectroscopy that the electrode exhibits features of single-particle electrodes. Thus, it is suitable for a direct determination of performance parameters characteristic of the active particles without the need to resort to a complicated porous-electrode modeling.

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Pt-Rh-Ru alloy catalysts for methanol electro-oxidation were prepared by electrochemical deposition under constant potential conditions. The Pt:Rh:Ru ratio was varied by changing electroplating solution composition. Obtained catalysts were examined electrochemically in acidic solutions containing methanol. Stripping voltammetry was applied to study adsorption of methanol on the electrodes surfaces while oxidation of methanol from solution was studied by means of chronoamperometry and cyclic voltammetry. The highest electrocatalytic activity was observed for an alloy with the highest obtained ruthenium concentration of 31%.The methanol electro-oxidation relies mainly on binary platinum-ruthenium alloy catalysts, which were found to be the most effective anodes for methanol oxidation in direct methanol fuell cell. 1 Each of components of the alloy plays a separate role: the platinum acts as an active site for methanol adsorption while the ruthenium properties are crucial for the process of oxidation of the adsorbate. Ruthenium is able to activate water with formation of metal-(OH) ads species at much lower potentials than pure platinum catalyst. As a result, ruthenium strongly improves full oxidation of adsorbed CO species via bi-functional effect. 2,3 Further enhancement of performance of DMFC catalysts can be achieved by addition of a third metal. The effect of third metal addition on electrochemical properties of catalyst was presented in the literature widely, e.g., Kowal et al. 4,5 have studied the influence of SnO 2 on behavior of PtRhSnO 2 . Lima and Gonzalez 6 have presented the electrochemical properties of Pt-Rh-Ru alloy. Higher activity and higher selectivity of ternary alloys in comparison to platinum are explained by the lattice mismatch, electronic interaction of Pt with Rh and Ru atoms and bi-functional mechanism. 4,6 In our previous work 7 we reported that PtRh alloys are slightly more tolerant for poisoning by CO and CO 2 than pure Pt and Rh. The onset potential for methanol oxidation for Pt-Ru, Pt-Rh or Pt-Pd showed improved specific activity towards the MeOH electro-oxidation. It is interesting then to study how Rh addition influences catalytic performance of Pt-Ru alloys applied for methanol oxidation.In this contribution we present the results of studies on methanol electro-oxidation on ternary Pt-Rh-Ru alloys. We discuss the influence of the alloy composition on adsorption of methanol and on oxidation of methanol dissolved in electrolyte.Pt-Rh-Ru electrodes were prepared by electrodeposition on 0.5 mm diameter gold wires (99.99 Au with the geometric area of 0.06 cm 2 ) from the solutions containing H 2 PtCl 6 , RhCl 3 and RuCl 3 dissolved in an aqueous 0.5 M HCl in various amounts. In all the solutions platinum to rhodium ratio was the same (1:1) while ruthenium to platinum ratio was varied from 1:1 to 3:1. The electrodeposition was carried out under applied potential of 0.15 V (versus SHE) for 15 min in a typical electrochemical cell consisting of Au wire, Hg, Hg 2 SO 4 |0.5 M H 2 SO 4 and pl...