Anion Adsorption on Pt(100) from Sulfuric Acid: Electrochemistry and Fourier Transform Infrared Spectroscopy

The adsorption of bisulfate and sulfate anions from 0.05M solution on Pt(100) was characterized by Fourier transform infrared spectroscopy (FTIR). Subtractively normalized interfacial FTIR spectra (SNIFTIRS) indicated only weak adsorption of bisulfate at potentials below 0.4 V (vs. ), in contrast to the strong adsorption seen on the (111) surface by the same technique. At potentials above 0.6 V the SNIFTIRS spectra were due entirely to diffuse layer species. At potentials between 0.4 and 0.6 V, changes in the IR bands indicated either a rearrangement (and possibly deprotonation) of adsorbed bisulfate or weak adsorption of sulfate ion.