Modulation of electrode performance and in situ observation of proton transport in Pt–RuO₂ nanocomposite thin-film electrodes

The relationship between the properties of ruthenium oxide and its electrode performance with respect to methanol electro-oxidation was investigated using a Pt–RuO₂ nanocomposite thin-film electrode fabricated by a cosputtering system. The performance of the nanocomposite electrode, consisting of a Pt nanophase and a RuO₂, was modified by heat treatment at different temperatures (100, 250, and 400 °C) which altered the proton and electron contributions in the electrodes. The transport of protons produced during methanol electro-oxidation in the Pt–RuO₂ nanocomposite electrode was directly observed during electrochemical reaction by means of the ectrochromism of RuO₂. It is concluded that improved electrical conduction that maintains the transport of protons is responsible for the enhanced electro-oxidation of methanol for 250 °C Pt–RuO₂. © 2003 American Institute of Physics.