Carbon monoxide oxidation on bimetallic Ru/Au(111) surfaces

Abstract

The electrochemical deposition of Ru on Au(111) was performed in 0.5 M H2SO4 + 10-4 M RuCl3. The obtained bimetallic Ru/Au(111) surfaces were characterised by cyclic voltammetry and in situ STM in 0.5MH2SO4. The Ru deposit consists of nanoscale islands, which merge with increasing coverage. Two different types of bimetallic Ru/Au(111) surfaces with respect to the distribution ofRu islands over the Au(111) substrate surface were obtained.When the deposition was performed at potentials more positive than the range of Au(111) reconstruction, homogeneous nucleation occured resulting in a random distribution of Ru islands. When the deposition was performed on reconstructed Au(111) at low overpotentials, selective nucleation occured resulting in the replication of the Au(111) reconstruction. Only at higher deposition overpotentials, can multilayer deposits be formed, which exhibit a very rough surface morphology. The electrocatalytic activity of such structurally well defined Ru/Au(111) bimetallic surfaces was studied towards CO oxidation with the Ru coverage ranging from submonolayer to several monolayer. COstripping commences at about 0.2Vand occurs over a broad potential range. The observed influence of the Ru structure on the CO stripping voltammetry is explained by local variations in theCOadsorption energy, caused by differences in the local Ru structure and by effects induced by the Au(111) substrate.

Keywords

• ru deposition
• au(111)
• bimetallic surfaces
• stm
• co-oxidation