ELECTROCHEMISTRY OF CYSTEINE ON LOW-INDEX SINGLE-CRYSTAL GOLD ELECTRODES

The chemisorption and redox properties of cysteine have been studied at Au(100), Au(111), and Au(110) single-crystal electrodes in dilute aqueous perchlorate solution using cyclic voltammetry. The appearance of the current peaks on the current potential curves depends on the the relative position of the point of zero charge. The oxidation of cysteine was found to be a two-step process, with the first step involving one electron and the second three electrons. The effects of gold surface reconstruction were pronounced for the Au(100) electrode. Resolution of the current due to gold oxidation and cysteine was realized using a transfer experiment in which an electrode with chemisorbed cysteine was transferred to and cycled in a cell containing no cysteine.