VOLTAMMETRY AND INSITU FOURIER-TRANSFORM IR SPECTROSCOPY OF 2 ANTHRAQUINONE DISULFONATES ADSORBED ON GRAPHITE-ELECTRODES

1,5- and 2,6-anthraquinone disulfonate irreversibly adsorbed on graphite electrodes were examined by cyclic voltammetry and in situ IR reflectance spectroscopy. Both adsorbed reactants exhibit multiple voltammetric peaks with magnitudes which change as the adsorption proceeds. Comparison of the voltammetric peaks with the IR spectroscopic responses, when they were present, indicated that the anthraquinones were adsorbed in configurations or on sites which changed with time and coverage. The results are consistent with a model in which each anthraquinone is initially adsorbed with its molecular plane parallel to the electrode surface but the orientation becomes more perpendicular to the surface as the adsorption proceeds.