摘要：

In-situ FTIR spectroscopic and electrochemical data, and ex-situ (emersion) electron diffraction (LEED and RHEED) and Auger electron spectroscopic (AES) data are presented on the structure and reactivity, with respect to the electro-oxidation of CO, of the Ru(0001) single crystal surfaces in perchloric acid solution. In both the absence and presence of adsorbed CO, the Ru(0001) electrode shows the potential-dependent formation of well-defined and ordered oxygen-containing adlayers. At low potentials (eg. from -80 to +200 mV vs Ag/AgCl), a (2 x 2)-O phase is formed, which is unreactive toward CO oxidation, in agreement with UHV studies; increasing the potential results in the formation of (3 x 1) and (1 x 1) phases at 410 mV and 1100 mV, respectively, with a concomitant increase in the reactivity of the surface toward CO oxidation. Both linear (CO_L) and threefold-hollow (CO_H) binding CO adsorbates (bands at 2000-2040 cm^-1 and 1770-1800 cm^-1, respectively) were observed on the Ru(0001) electrode. The in-situ FTIR data show that the adsorbed CO species still remain in compact islands as CO oxidation proceeds, suggesting that the oxidation occurs at the boundaries between the CO_ad and active O_ad domains via the Langmuir-Hinshelwood mechanism. At low CO coverages,reversible relaxation, (at lower potentials), and compression, (at higher potentials), of the CO_L adlayer were observed and rationalised in terms of the reduction and formation of surface O-adlayers, The data obtained from the Ru(0001) electrode are in marked contrast to those observed at polycrystalline Ru, where only linear CO is observed.

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