Preparation And Analytical Applications Of Modified Electrodes Containing Graphene & Graphene -like Materials With Nanosemiconductors

In this paper, graphene(GN) and MoS2 were used as original material to prepare several nanocomposites. The X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and a variety of analytical methods were used to characterize these nanocomposites. Then we studied the nanocomposites in electrochemical analysis and catalysis application. The contents of this thesis were described as follows:1. CuS/GN nanocomposites were synthesized via reduction of ethylene glycol. An electrochemical sensor based on CuS/GN nanocomposites was fabricated for sensitive detection of esculetin. The nanocomposite was characterized by XRD and TEM. The electrochemical behavior of esculetin was studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The results indicated that the synergistic effect between CuS nanoparticles (NPs) and graphene enhanced the electrochemical response of esculetin. Under the optimal conditions, the DPV peak current increased linearly with the esculetin concentration in the range from 1.0×10-7 to 1.0×10-4 mol L-1, and the detection limit was 5.8×10-8 mol L-1. Furthermore, a good selectivity with high sensitivity was obtained for the determination of esculetin in real samples.2. A novel thymol electrochemical sensor based on CeO2 nanoparticles-decorated graphene hybrid was introduced. The hybrid was characterized by XRD, TEM and XPS. The electrochemical behavior of thymol on the CeO2/GN modified glassy carbon electrode was investigated by CV and DPV. Compared with bare glassy carbon electrode, the proposed electrode showed improved analytical performance characteristics in catalytic oxidation of thymol. Under the selective conditions, the modified electrode showed a linear voltammetric response for the thymol within a concentration range of 1.0×10-7 to 1.8×10-5 mol L-1, and a value of 5.0×10-8 mol L-1 was calculated for the detection limit. Furthermore, a good selectivity with high sensitivity was obtained for the determination of thymol in real samples.3. A novel honokiol electrochemical sensor based on MoS2/GN nanohybrid was introduced in this work. The hybrid was characterized by XRD, TEM, SEM and XPS. The electrochemical behavior of honokiol on the MoS2/GN modified glassy carbon electrode was investigated by CV and DPV. The proposed electrode showed improved analytical performance characteristics in catalytic redox of honokiol. Under the optimal conditions, the modified electrode showed a linear voltammetric response to the honokiol with a concentration range from1.0×10-9 to 2.5×10-6 mol L-1, and the detection limit was estimulated at 6.2×10-10 mol L-1. Moreover, the sensor also exhibited good reproducibility and stability, and could be used for the detection of honokiol in pharmaceutical samples.4. The MoS2/MoSe2 hybrid was synthesized by a solvothermal reaction. The hybrid was characterized by XRD, TEM and XPS. Due to highly exposed S and Se active edges and significant synergistic combination of MoS2 and MoSe2, the MoS2/MoSe2 catalyst exhibits superior hydrogen evolution reaction (HER) activity with a low overpotential of about 0.40 V (vs. SCE) and a large cathodic current density (4.84 mA/cm2 at an overpotential of 0.45 V). Therefore, the MoS2/MoSe2 hybrid could be expected to split water with high efficiency and ensure a renewable and economical production of hydrogen.