Adsorption of bisulfate on the Ru(0001) single crystal electrode surface

Adsorption of anions from sulfuric acid solutions has been studied on Ru(00 01) single crystal and polycrystalline surfaces by electrochemical techniqu es and in-situ Fourier transform infrared spectroscopy. Infrared spectrosco py shows that bisulfate is the anion adsorbed on the Ru(0001) surface. The bisulfate adsorption is detected at the H-2 evolution potential and extends into the potential region where the Ru surface is oxidized. A method for e xtracting unipolar bands from bipolar bands has been presented. The tuning rate of adsorbed bisulfate in the double layer potential region of Ru(0001) was found to be significantly smaller than those observed for other platin um metals. This has been ascribed to a small change in bisulfate coverage o n Ru(0001) in this potential range. Bisulfate vibration frequencies are hig her on this surface than at any face-centered cubic metal with the (111) or ientation. Oxidation of the Ru(0001) surface is limited to one electron per Ru atom, distinctly different from the high degree of oxidation seen in po lycrystalline surfaces. For oxidized polycrystalline Ru, only solution phas e sulfates and bisulfates are observed in the IR spectra. (C) 2001 Elsevier Science B.V. All rights reserved.