In situ FTIR studies of the effect of temperature on the adsorption and electrooxidation of CO at the Ru(0001) electrode surface

The adsorption and electrooxidation of CO at a Ru(0001) electrode in perchl oric acid solution have been investigated as a function of temperature, pot ential and time using in situ FTIR spectroscopy. This builds upon and exten ds previous work on the same system carried out at room temperature. As was observed at room temperature, both linear (COL) and 3-fold-hollow (COH) bi nding CO adsorbates (bands at 2000-2045 cm(-1) and 1768-1805 cm(-1), respec tively) were detected on the Ru(0001) electrode at 10 degreesC and 50 degre esC. However, the temperature of the Ru(0001) electrode had a significant e ffect upon the structure and behavior of the CO adlayer. At 10 OC, the in-s itu FTIR data showed that the adsorbed CO species still remain in rather co mpact islands up to ca. 1100 mV vs Ag/AgCl as the CO oxidation reaction pro ceeds, with oxidation occurring only at the boundaries between the COad and active surface oxide/hydroxide domains. However, the IR data collected at 50 degreesC strongly suggest that the adsorbed CO species are present as re latively looser and weaker structures, which are more easily electro-oxidiz ed. The temperature-, potential-, and coverage-dependent relaxation and com pression of the COL adlayer at low coverages are also discussed.