Electrochemical dissolution of Pt-Pd-Ru alloys

The electrochemical dissolution of Pt-Pd-Ru ternary alloys has been studied in 0.5 M H2SO4 aqueous solutions by cyclic voltammetry and the electrochemical quartz crystal microbalance (EQCM). The amounts of dissolved metals from Pt, Pd and Ru electrodes as well as from their alloys during voltammetric polarization to various upper potential limits have been determined. Under the conditions of a single voltammetric cycle in the range 50–1360 mV vs. SHE (0.01 V/s) Pt-Pd-Ru alloys are more resistant to dissolution than both pure Pd and Ru, but more prone to dissolution than pure Pt. The effect of continuous voltammetric cycling in a fixed potential range on alloy dissolution, composition changes and real surface area modifications was also examined. During the repeated polarization to the potentials of surface oxidation the alloys become impoverished in Ru and the surface roughness decreases. Prior hydrogen electrosorption probably leads to an increase in the surface homogeneity, which results in a greater alloy stability during prolonged voltammetric polarization to high potentials.