Fabrication Of Graphene Modified Electrode And Its Application For Electrochemical Detection Of Micromolecules

Graphene (GR) based materials have been used to the modification of electrode due to the excellent properties of GR such as high specific area, high electrical conductivity and electron transfer rate. In this thesis, different kinds of GR modified electrodes were fabricated and used to investigate the electrochemical behavior of various micromolecules. The thesis can be summarized as follows:1. Chitosan-GR and Au-GR composite film were used to modify a1-ethyl-3-methylimidazolium tetrafluoroborate based carbon ionic liquid electrode (CILE) by drop coating and cyclic voltammetric reduction, respectively. The modified electrodes were characterized by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The electrochemical behaviors of bisphenol A and hydroquinone were studied on the modified electrodes and compared with the unmodified electrodes with the electrochemical parameters calculated, respectively. Under the optimal conditions the oxidation peak current was in linear with the concentration and the detection limit (3a) was calculated by differential pulse voltammetry. The modified electrodes were applied to the detection of samples with satisfactory results.2. An ionic liquid1-butylpyridinium hexafluorophosphate based CILE was prepared and used as the substrate electrode. Then a poly(methylene blue) functionalized GR and poly(crystal violet) functionalized GR composite film were coelectrodeposited on the CILE surface by cyclic voltammetric reduction and potentionstatic reduction, respectively. The fabricated PMB-GR/CILE and PCV-GR/CILE were characterized by SEM and EIS, respectively. The electrochemical behavior of dopamine was investigated on PMB-GR/CILE with its work curve obtained by differential pulse voltammetry. Separation of the oxidation peak potential for hydroquinone (HQ) and catechol (CC) was112V obtained on PCV-GR/CILE, which made it suitable for simultaneous determination of HQ and CC. Simultaneous determination and analysis application were also studied on the modified electrode, respectively.3. An ionic liquid1-hexylpyridinium hexafluorophosphate based CILE was prepared and used as the substrate electrode. Graphene oxide (GO) was modified on CILE surface (GO/CILE) and acridine orange was further electropolymerization on GO/CILE surface by cyclic voltammetriy with the simultaneously electrochemical reduction of GO to GR, which gave a poly(acridine orange) functionalized GR modified CILE. The modified electrode exhibited good electrochemical performances with higher conductivity and lower electron transfer resistance. The modified electrode was used to investigate the electrochemical oxidation of rutin and the rutin tablet samples were detected with satisfactory results.