Adsorption and oxidation of rhodamine B at ZnO electrodes

Abstract

The adsorption of Rhodamine B on the (0001) face of ZnO single crystals from an aqueous solution was monitored through measurement of the absorbance of the adsorbed dye. Analysis of these spectra yielded a Langmuir‐type adsorption isotherm with a plateau surface concentration of 1.1×10⁻⁷ mmoles/cm². A comparison was made between the absorbance of the adsorbed dye and that of the dye in solution. These data were correlated with electrochemical measurements of the photo‐oxidation of this dye at ZnO crystals used as electrodes. The quantum efficiency of photo‐oxidation was 0.027, which was approximately constant as a function of surface coverage. A kinetic model was formulated for the time decay of the photocurrent.