SURFACE RAMAN-SPECTROSCOPIC INVESTIGATION OF PYRIDINE ADSORPTION AT PLATINUM-ELECTRODES - EFFECTS OF POTENTIAL AND ELECTROLYTE

Surface enhanced Raman spectra of pyridine (Py) at Pt electrodes have been investigated as a function of potential and supporting electrolyt e. The results show a large difference from those reported for coinage metal electrodes of Ag, Au and Cu, emphasising the effective involvem ent of chemical enhancement on Pt surfaces. At very negative (or posit ive) potentials, Raman spectra show the competitive coadsorption of hy drogen (or oxygen-containing species) with Py, and in acidic solutions , PyH+ ions prefer to dissociate into Py adsorbed on Pt surfaces even in the presence of chloride ions. The differences in the surface bondi ng strength for Py on Pt and coinage metal electrodes are explained in terms of the different electronic configurations of the metals.