IN-SITU STM AND IR STUDIES OF PHENOXIDE ELECTROOXIDATION ON AU(111) ELECTRODE SURFACES

The STM has been used to monitor the electrooxidation of phenoxide to oligophenol on Au(lll) in alkaline solutions. Prior to oxidation, phenol associates as phenoxide to Au(111) in a (root 3 x root 3)R30 degrees structure with the molecule oriented end-on through the O atom. After oxidation, a disordered, close-packed array of oxidation products consisting of monomer, dimers, trimers, and a few higher lengths are observed. The oxidation products are oriented with the ring roughly parallel to the electrode surface. IR studies conducted prior to oxidation confirm the nonparallel orientation of the ring relative to the electrode surface and show that the orientation of the molecule does not change with potential through the double layer region of the voltammetry.