SURFACE STUDIES OF PT-RU ELECTRODEPOSITS ON GOLD

Auger electron spectroscopy, energy dispersive X-ray techniques and X-ray diffraction were used for the characterization of platinum-ruthenium electrodeposits prepared on gold. SEM-EDAX analysis showed that the gold surface is totally covered by a homogeneous electrodeposit after 30 min of potentiostatic electrodeposition at 0.05 V vs. the. The AES analysis of the low kinetic energy peaks revealed that the electrodeposits with more Pt, presented more oxygen on the surface and those deposits with higher intensity ratio of Ru showed more oxygen in bulk. The composition of the deposits calculated from MNN transitions showed that the surface is enriched in Pt. On the basis of the XRD spectra, the electrodeposits, with Pt/Ru ratio higher than 1.5, form alloys. The catalytic activity was observed in 3.5 NH2SO4 + 2 M methanol solution at 70 degrees C. The electrodeposit with 80% Pt and 19% Ru and 1% O (at 5 nm) exhibited the highest apparent current density at 450 mV vs. the, for the oxidation of methanol.