Study of Bisulfate Adsorption on Pt(111) Single Crystal Electrodes Using In-situFourier Transform Infrared Spectroscopy

摘要

Subtractively normalized interfacial Fourier transform spectroscopy (SNIFTIRS)has yielded the first spectroscopic evidence that bisulfate anion adsorption is associated with the anomalous peaks seen in the cyclic voltammetry of Pt(111) in sulfuric acid. The infrared data indicates that the beginning of bisulfate anion adsorption coincides with the onset of the anomalous peak region (0.15 V vs. SCE in 0.05 M H2SO4). The same IR spectra afford no evidence of sulfate anion adsorption on the Pt(111) single crystal electrode, over the potential range studied (-0.26 to +0.70 V vs. SCE). Over this same potential region the adsorbed bisulfate absorption peak frequency showed a strong potential dependence. This increase in peak frequency with increasingly positive potentials is rationalized using molecular orbital arguments.