Cyclic voltammetric and surface Raman spectroelectrochemical behavior of the anion of dithizone (diphenylthiocarbazone), HDz-, has been characterized at a Au electrode in aqueous alkaline media. The cyclic voltammetric results suggest that HDz- interacts with the Au electrode surface. The surface Raman spectroelectrochemical data are consistent with weak adsorption of HDz- at the Au surface. At potentials negative of 0 V, this adsorption appears to be weak relative to the previously noted adsorption of HDz- at Ag and Cu electrode surfaces. At potentials anodic of 0 V, oxidation of HDz- to the corresponding disulfide occurs. This disulfide adsorbs at the Au surface in multilayer quantities. The effect of solubility on the extent of adsorption was also investigated. The surface Raman data indicate that adsorption of HDz- is greater from pH 10 solution than from pH 12 solution. The adsorbed HDz- is postulated to reside in the outer Helmholtz plane in which it is still solvated, based on a comparison of the adsorbed HDz- spectra and a solution HDz- spectrum. This is in contrast to the behavior observed previously at Ag and Cu wherein the HDz- is thought to be contact adsorbed.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry