Synthesis and characterisation of carbon-supported PtGe electrocatalysts for CO oxidation

Platinum-germanium catalysts supported on carbon were synthesised from orga nometallic precursors using surface organometallic chemistry (SOMC). The ca talysts were characterised using chemisorption, X-ray absorption spectrosco py, transmission electron microscopy, energy dispersive X-ray analysis, X-r ay diffraction and cyclic voltammetry. Physical characterisation provided e vidence for the selective deposition of the germanium with the platinum usi ng SOMC, existing mainly as platinum metal in association with GeO2. From a nodic stripping cyclic voltammetry it can be inferred that the presence of GeO2, at the platinum sites changes the CO oxidation profile of strongly ad sorbed CO, increasing its oxidation at 0.68 V versus RHE relative to the ma in oxidation at 0.85 V versus RHE. The peak potentials appear to be indepen dent of the germanium loading; however, significant changes were observed i n the peak current densities, with an increased promotional effect at highe r germanium content. We believe the change in the relative distribution bet ween these sites is mainly due to changes in the surface structure of the p latinum on addition of GeO2. Further promotional activity is seen, with a l imited oxidation activity evident at an onset of 0.35 V versus RHE. (C) 200 1 Elsevier Science Ltd. All rights reserved.