44 CIENCIAS Preparation, Characterization, and Electrochemical Behavior of Organothiols Self-Assembled Monolayers on Polycrystalline and Thin Films Gold Electrode Surfaces This research is focused on electrochemical behavior study of an aromatic SAM’s of 4-aminothiophenol (4-ATP), which has not been widely studied. Cyclic Voltammetry (CV) is the electroanalytical technique used in this project to correlates current(i) with applied potential (V). CV serves as a fingerprint of the electrode surface. 4-ATP adsorbs spontaneously and forms a stable (in a certain range of potential) and reproducible monolayer at polycrystalline Au electrode. Stability, electrochemical oxidation and desorption process from homogeneous and oxidized mixed surface-confined adsorbed 4ATP SAM’s were studied. Results showed that adsorbed 4ATP was stable in potentials below 0.5V and electrochemical oxidation of this monolayer occurs at 0.7V. A different structure of the monolayer was formed after the electrochemical oxidation which generates two surface-confined redox pairs. By controlling the experimental procedures, it is possible to generate different oxidized mixed SAM’s. Differences in voltammetric responses related to the SAMs desorption processes show that different structures are adsorbed onto Au surface. Electrochemical redox-probes responses were used i) to demonstrate that SAM’s were adsorbed uniformly onto Au surface and ii) to differentiate electrode surface composition. Also, it is possible to prepare, and characterize thin film Au electrodes, from Au recycled fragments, that show preferentially oriented Au (111) domains. The electrochemical oxidation of adsorbed 4ATP was carry out at thin film Au electrodes which also generates two pair redox surface-confined products. Reductive desorption voltammetric responses were found for different monolayers of adsorbed 4ATP, suggesting that different structures are adsorbed on the Au surface. lynette y. camacho caraballo maestría en ciencias con especialidad en química mentor: dra. margarita rodríguez lópez electrochemistry surface science gold electrodes organothiols self assembled monolayers
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