ANODIC-OXIDATION OF METHANOL AT A GOLD-MODIFIED PLATINUM ELECTROCATALYST PREPARED BY RF-SPUTTERING ON A GLASSY-CARBON SUPPORT

A Au-Pt bimetallic model catalyst has been prepared on a smooth carbon support by an RF sputtering method, and its electrocatalytic activity for methanol oxidation has been investigated in a sulfuric acid solution. The activity of the sputtered Pt film modified with a small amount of Au deposit was evaluated by the current density in a potential-sweep voltammogram and a steady-state polarization curve. The apparent current density for methanol oxidation based on the geometric area of the electrode was decreased by increasing the Au coverage of the catalyst. In potential-sweep voltammetry, the activity per Pt site exposed to the solution reached a maximum value at 70-80% Au coverage. However, the steady-state activity of the Au-modified Pt catalyst was almost the same as that of the pure Pt film. The XPS measurement showed that the valence band spectrum of the Au-modified Pt catalyst prepared by RF sputtering consists of a linear combination of the spectra observed at pure Pt and Au films.