Electrooxidation of small organic molecules on mesoporous precious metal catalysts I: CO and methanol on platinum

Nanostructured platinum prepared by the chemical reduction of hexachloroplatinic acid dissolved in aqueous domains of the liquid crystalline phases of oligoethylene oxide surfactants has been examined as an innovative model electrocatalyst. Owing to its high specific surface area and periodic mesoporous nanostructure, electrooxidation of both carbon monoxide and methanol has been investigated using cyclic voltammetry and chronoamperometry as a probe of the electrocatalytic properties of this material. The oxidation of CO adsorbed on the new type of platinum is determined by the rate of an adsorption and nucleation-growth controlled phase transformation occurring inside the CO adlayer. This mechanism appears to be different from the traditional Langmuir–Hinshelwood model for CO oxidation. The methanol electrooxidation reaction appears to proceed mainly through a direct pathway with CO2 as the final product and the potentiostatic current attains a steady-state value even at low potentials (<0.5 V). These results are very important since the nanostructured platinum shows a much lower poisoning rate at potentials relevant to fuel cell operation. Enhanced electrocatalytic durability to the methanol oxidation reaction is obtained on this new type of platinum in comparison to one high surface area platinum from Johnson–Matthey plc.