Application Of Self-assembled Monolayer On Gold Nanoparticle-Modified Electrode In Environmental Analysis

In this thesis, a gold nanoparticles modified glassy carbon electrode (Au/GCE) was prepared with the seed-mediated nano-metal growth method. Four kinds of phenolic compounds were first selected to study the response on the Au/GCE surface, and the results were analyzed and compared respectively with the response on bare glassy carbon and planar gold electrodes. Then, to fabricate L-cysteine monolayer on gold nanoparticle-based electrode (L-cys/Au/GCE) and 3-mercaptopropionic acid monolayer on gold nanoparticle-based electrode (MPA/Au/GCE), L-cysteine and 3-mercaptopropionic acid were assembled on the gold nanoparticle modified electrode by combining thiols with gold. Furthermore, the current responses of copper (II) on the surfaces of these modified electrodes were studied. As the results, the following descriptions were addressed.(1) Compared with bare glassy carbon electrode and planar gold electrode, the Au/GCE was proved to have electrocatalytic effect on catechol, resorcinol, hydroquinone and phenol. And the peak potentials of these phenolic compounds were found to be related with their structures.(2) Chronoamperometric responses of resorcinol, hydroquinone and phenol on the Au/GCE were found to have quick responses.(3) Copper (II) showed good electrochemical response on the L-cys/Au/GCE. The current response was observed to reach a plateau level within 2-h monolayer modification time. And the negative shifts in both the anodic and cathodic peaks potential were found to be linear with the increase of pH. In addition, a plateau response was reached after pre-concentration about 2 min. The anodic and cathodic peak currents enhanced linearly with scan rate, meaning a surface redox reaction of adsorbed copper (II) on L-cys/Au/GCE electrode surface.(4) Both the anodic and the cathodic peaks currents were found to be linear with copper (II) concentration from 1μg/L to 500μg/L. The anti-interference ability of this electrode was also studied by adding common ions and other metal ions with satisfied results. (5) Obvious redox wave was observed on the MPA/Au/GCE at low applied voltage and pre-concentration time. The redox of accumulated copper(II) on MPA/GNP/GC electrode was a surface controlled process. With increasing pH, both anodic and cathodic peak potentials shifted linearly to the negative direction. And the anodic and cathodic peaks currents were increased with prolonging pre-concentration time.(6) A linear relationship between the stripping current and the concentration of copper (II) in the range of 0.1-100μg/L was found. The recovery experiment in tap water and the reproducibility results demonstrated that MPA/GNP/GC electrode was suitable for fast detection of copper(II) in water sample with good stability.