Fabrication Of Molybdenum Dichalcogenide Nanocomposites Modified Glassy Carbon Electrodes And Their Applications In Analytical Chemistry

In this master thesis, molybdenum dichalcogenide with the photocatalytic property were used as original materials to synthesize several kinds of nanocomposites by combining with other different functional materials. The obtained nanocomposites were used to modify glassy carbon electrodes (GCE) for fabrication of electrochemical sensors. Finally, these sensors were applied to investigate pharmaceutical analysis and hydrogen peroxide detection and so on. The contents are described as follow:1. Poly (diallyldimethylammonium chloride) (PDDA) functionalized graphene-MoS2 nanoflower materials (PDDA-G-MoS2) were successfully synthesized. And gold nanoparticles (AuNPs) were assembled on the surface of PDDA-G-MoS2 via electrostatic attractive force and theory of Au-S bond. Finally, the obtained Au/PDDA-G-MoS2 nanomaterial was modified on GCE to construct Au/PDDA-G-MoS2/GCE electrochemical sensor and applied to the sensitive detection of eugenol. The electrochemical performance of modified electrodes and the characteristic of eugenol reaction on the modified electrodes were investigated by cyclic voltammetry (CV).Different concentrations eugenol were added in 0.10 mol L"1 NaAc-HAc buffer solution (pH=5.50) at +0.582 V continuously, and the work curve of eugenol was obtained by amperecurrent response. The oxidation peak current of eugenol increased linearly with addition of concentration in the range from 0.1 μmol L-1 to 440 μmol L-1 with a low limit of detection of 0.036 μmol L-1. This analytical method has been applied to determination of eugenol in real samples with satisfactory results.2. Platinum nanoparticles (Pt) were synthesized by MoS2 as template via the facile hydrothermal method. The as-prepared nanocomposites (Pt-MoS2) were characterized by transmission electron microscope (TEM), high resolution transmission electron microscope (HRTEM), electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS). The nanomaterials were modified on GCE to fabricate Pt-MoS2/GCE biosensor for the enzyme-like catalysis towards hydrogen peroxide (H2O2). The CV and amperometry were used to study the electrochemical behaviors, and the biosensor exhibited high electrochemical activity for the reduction reactions of H2O2 in N2 saturated phosphate buffer solution (PBS). The reduction current of H2O2 increased linearly with addition of concentration in the range from 4×10-6 to 4.85×10-2 mol L-1 with a low detection limit of 0.001 mM. The present work indicated that Pt nanoparticles could be synthesized on the surface of MoS2 due to interface Pt-S bond and can be obviously enhanced the catalytic activity of platinum nanoparticles compared to the individual Pt.3. Molybdenum diselenide (MoSe2) with different morphologies were prepared through a facile hydrothermal method. The as-prepared composites were characterized by field-emission scanning electron microscopy (FESEM), HR-TEM, X-ray diffraction (XRD) and XPS. The different morphologies MoSe2 were used to modify GCE. The linear scan voltammetry (LSV), CV and tafel curves were used to investigate the electrochemical behaviors of MoSe2/GCE and catalytic activity to hydrogen evolution reaction (HER). The present work suggested that the morphology of MoSe2 could be controlled by changing the ratio of molybdenum and selenium to affect the catalytic activity to HER.