The Thioacetate-Functionalized Self-Assembled Monolayers on Au: Toward High-Performance Ion-Selective Electrode for Ag+

Two classes of morpholino-substitued thioacetate have been successfully synthesized and their electrochemical properties of self-assembled monolayers (SAMs) on Au electrode are measured by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The barrier property of the SAMs-modified surfaces is evaluated by using potassium ferro/ferri cyanide. The results suggest that the arenethioacetate forms higher-quality close-packed blocking monolayers in comparison with alkanethioacetate. Furthermore, it has shown that the barrier properties of these monolayers can be significantly improved by mixed SAMs formation with decanethiol. From our experimental results we find that the electron transfer reaction of $[Fe(CN)_6]^{3/4-}$ redox couple occurs predominantly through the pinholes and defects present in the SAM and both SAMs show a good and fast capacity in recognition for $Ag^+$. The morphological and elementary composition have also been examined by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS).