Studies on Self-Assembled Alkanethiol Monolayers Formed at Applied Potential on Polycrystalline Gold Electrodes

Abstract

1-Dodecanethiol assembly on polycrystalline gold electrodes at fixed positive potentials has been investigated by chronoamperometry and electrochemical quartz crystal microbalance and the films formed characterized by cyclic voltammetry and electrochemical impedance spectroscopy. It was found that 1-dodecanethiol adsorption on gold is enhanced by application of positive potentials to the electrode surface and that adsorption proceeds faster than in the case of open circuit deposition. Compact defect-free monolayers of capacitance values of 1.1-1.6 muF cm-2 are produced in time intervals as short as 100 s, with no roughness, as demonstrated for the first time by electrochemical impedance analysis. Control of surface potential during alkanethiol assembly appears to improve monolayer quality and to allow for shorter assembly periods. Monolayers can be removed by cycling in alkaline solution or in dilute sulfuric acid. These results are important for the fast construction of defect-free bilayers.