Potential Dependent Chromate Adsorption on Gold

The adsorption and reduction of chromate on Au(111) were studied using cyclic voltammetry (CV), surface enhanced Raman spectroscopy (SERS), in situ atomic force microscopy (AFM), and scanning tunneling microscopy in slightly acidic media. CV results show the evolution of the species present with each subsequent scan revealing intermediate processes in the deposition of chromate on the surface. SERS indicates that the deposition involves oxidation and reduction cycles between chromate and alpha-Cr(2)O(3). The intermediate step involves a chromate species chemically bound to the surface. The final film is a mixed Cr(III)/Cr(VI) layer. In situ AFM demonstrates that the Cr(2)O(3) adlayer exhibits a (root 3 x root 3)R30 degrees adlattice relative to the underlying Au(111). (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3223665] All rights reserved.