IN-SITU FTIRS INVESTIGATIONS OF SURFACE PROCESSES OF RH ELECTRODE - NOVEL OBSERVATION OF GEMINAL ADSORBATES OF CARBON-MONOXIDE ON RH ELECTRODE IN ACID-SOLUTION

With the help of in situ multi-step FTIR Spectroscopy, two types of ad sorbed geminal CO have been observed for the first time at an electroc hemically modified Rh electrode. A doublet band of two broad peaks at 2166 and 2112 cm(-1) is assigned to geminal CO on Rh surface oxide (or hydroxide) produced by the electrochemical modification process, and a doublet band of two peaks near 2103 and 2033 cm(-1) is ascribed to g eminal CO on surface clusters of Rh formed by reduction of Rh surface oxide. Based on the evolution of FTIR spectra with the electrode poten tial, the surface processes of a Rh electrode, subjected to a potentia l cycling treatment at 1.5 V s(-1) between -0.275 and 2.4 V for 2 min, have been elucidated. The present results at the solid/liquid electro chemical interface were compared with those obtained at the solid/gas interface, and consistent conclusions were achieved.