Electrooxidation of small organic molecules on mesoporous precious metal catalysts II: CO and methanol on platinum-ruthenium alloy

Mesoporous Pt-Ru alloy has been successively prepared by the chemical co-reduction of hexachloroplatinic acid and ruthenium trichloride both dissolved in aqueous domains of the liquid crystalline phases of an oligoethylene oxide surfactant using Zn metal reductant. The resultant material containing mesoporous structures has a high specific electrochemical surface area and has been examined as an electrocatalyst towards the electrooxidation of CO and methanol using cyclic voltammetry and chronoamperometry. The rate of electrooxidation of adsorbed CO on the mesoporous Pt-Ru electrode can be modelled by the nucleation and growth of CO free holes under a process that involves 2D nucleation and 2D surface diffusion-controlled growth. Methanol is oxidized mainly via a direct pathway to soluble products on the mesoporous Pt-Ru electrode and steady-state kinetics can be attained even at low potentials. The electrocatalytic activity of the mesoporous PtRu towards methanol oxidation is favourable compared to an ultrafine Pt-Ru electrocatalyst with similar bulk composition. (C) 2003 Elsevier Science B.V. All rights reserved.