Carbon monoxide, methanol and ethanol electro-oxidation on Ru-decorated carbon-supported Pt nanoparticles prepared by spontaneous deposition

Carbon-supported Pt nanoparticles (Pt/C) were modified by spontaneous deposition of Ru species in 0.1 M HClO4 solutions with different Ru concentrations and treatment duration. Cyclic voltammetry (CV) of thin-layer electrodes in 0.5 M H2SO4 allowed determining the coverage θ of Pt by the Ru deposits. The CO oxidation activity of the Ru-decorated Pt specimens (Ru(Pt)/C) was evaluated by CO stripping measurements in the same background electrolyte. The activity towards methanol and ethanol oxidation was tested using CV in 0.5 M H2SO4 with 1.0 M CH3OH or 1.0 M CH3CH2OH. A promotional effect of all the anodic reactions due to the introduction of Ru species was detected, with a significant reduction of the overpotential in all cases. The optimum coverage for achieving the best CO oxidation activity and the highest current for the oxidation of these alcohols was found around θ = 0.20–0.30, indicating the involvement of CO as intermediate in the oxidation pathway of both, methanol and ethanol. The observed activation was mainly assigned to the deposited hydrous Ru oxide (RuOxHy). The Tafel slopes were analyzed and discussed on the basis of the presence of Ru species and the proposed mechanism for each oxidation reaction.