| Graphene nanosheet, as a “rising star†nanostructured carbon material, has been widely used in the preparation of the sensor due to its excellent adsorption capacity, relatively large specific surface area, high electrical conductivity and electrocatalytic activity. Meanwhile,metal nanoparticles possess large surface area, high surface energy and catalytic activity,using to construct the sensor. However, the morphology, particle size and dispersion of metal nanoparticles closely related to their nature. The studies found that grapheme, as load matrix,can increase the loading amount of metal nanoparticles, improve their dispersibility, and maintain or enhance the catalytic activity effectively. Furthermore, the synergistic effect of graphene and metal nanoparticles can improve the properties of electrochemical sensors and promote their development effectively. This dissertation focused on the study of ionic liquid functionalized graphene by covalent functionalized approach and applied to determine 5-HT and DA simultaneous. Meanwhile, the nonenzyme hydrogen peroxide sensor was fabricated based on non-covalent functionalized graphene and metal nanoparticles. The main contents were summarized as follows:1. Ionic liquid functionalized graphene(IL-graphene) was prepared by a nucleophilic ring-opening reaction between the amine group of an amine-terminated imidazolium ionic liquid(IL-NH2) and the epoxy groups of graphene oxide, thereby improving the dispersibility and conductivity of graphene. Then IL-graphene was dropped on the surface of a GCE to determine 5-HT and DA simultaneous. The experimental results showed that the electrochemical sensor exhibited good catalytic activity toward the oxidation of 5-HT and DA.It can not only individual determine 5-HT and DA, but also determine their mixtures. A linear response was obtained between the oxidation peak currents and 5-HT concentrations in the range of 2.0×10-7to 1.0×10-5mol/L with a detection limit of 6.7×10-8mol/L(S/N=3). With regard to DA, the linear range was obtained from 1.0×10-6 to 1.0×10-4 mol/L with a detection limit of 3.3×10-7 mol/L(S/N=3). The excellent performance of electrochemical sensor was ascribed to the network-like structure of IL-graphene, which provides large surface area to contact 5-HT and DA. Meanwhile, ionic liquid have high ionic conductivity, accelerating the electron transfer rate of 5-HT and DA.2. A simple and enzymeless amperometric sensor was fabricated for hydrogen peroxide determination based on one-pot synthesis of highly dispersed PtAu nanoparticles-CTAB-graphene nanocomposites. The hydrogen peroxide can be effectively detected by the sensor because CTAB functionalized graphene provided large amounts of anchoring sites for achieving a high dispersion of small size PtAuNPs and PtAuNPs will lead to higher catalytic ability for hydrogen peroxide. The experimental results demonstrated that that the sensor exhibited excellent electrochemical responses for the electrocatalytic reduction of hydrogen peroxide, and obtained a wide linear range from 5.0 × 10-9~4.8 × 10-6mol/L with a low limit of detection(LOD) of 1.7 × 10-9 mol/L. Moreover, the sensor showed good selectivity and reproducibility, and can be applied to real samples analysis.3. The surfactant, sodium dodecyl benzene sulfonate, was used to non-covalent functionalize graphene to improve dispersibility and increase specific surface area of graphene. Then Pd nanoparticles(PdNPs) were loaded on SDBS-GR by electrodepositing,using to determine hydrogen peroxide. The experimental results demonstrated that the constructed electrode exhibited good catalytic activity toward the hydrogen peroxide, and obtained a wide linear range(1.0×10-9~1.2×10-7 mol/L), a low limit of detection(4×10-10mol/L) with good selectivity and stability, and can also be applied to real samples analysis.The excellent performance of hydrogen peroxide sensor were ascribed that SDBS functionalized graphene load large amounts of PdNPs and the synergistic amplification effect of PdNPs and SDBS-GR. |
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