The adsorption of hydroquinone and p-benzoquinone on Pt electrodes in 1 M HClO4 has been examined by reflection-absorption infrared spectroscopy and cyclic voltammetry. At solute concentrations below 0.1 mM no spectral features were observed by RAIS in the 2700-3200-cm-1 region. Cyclic voltammetry indicated less than a twofold increase in adsorbate coverage when the solute concentration was increased from 0.075 to 0.75 mM while the infrared spectra clearly showed four absorption bands, characteristic of diphenols. These results indicate a transition from flat to edgewise orientation of the adsorbed species. The results suggest that both hydroquinone and benzoquinone adsorbed from concentration above 0.75 mM as 2,3-η2 edge-bonded diphenols. The applicability of separating the electrode from the electrolyte for spectroscopic examination is also demonstrated.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry