Sulfate adsorption on Cu(111) studied by in-situ IRRAS and STM: revealing the adsorption site and desorption behavior

Sulfate adlayers on a copper(111) electrode were investigated by in-situ in frared reflection absorption spectroscopy (IRRAS) combined with in-situ sca nning tunneling microscopy (STM). The latter data show clear evidence for a bridging bidendate coordination of sulfate to the copper surface. The IR s pectra exhibit one single absorption band in the frequency range of 1205-12 25 cm(-1). Further analysis of the band frequency and intensity with respec t to the electrode potential leads to sulfate desorption with sulfate remai ning in islands at the surface during the desorption process. This model is supported by additional STM measurements of the desorption behavior. (C) 1 999 Elsevier Science B.V. All rights reserved.