| With the development of economy, the mankind is faced with energy and environmental crisis. In order to solve the problems, molybdenum disulfide nanosheets, nanotubes and their composites were prepared by some new synthetic methods. These new materials were applied in dye sensitized solar cell, photocatalysis and anti-microbial. Specifically, the research contents are summarized as follows:1. Exfoliated MoS2 of ultra-small sheets were for the first time synthesized by embedding the precursors ((NH4)6Mo7O24·4H20 and thiourea) inside the hydrogel of the activated silicic acid (calculated as SiO2) which was obtained from hydrolysis of tetraethylorthosilicate (TEOS). It was found that the hydrogel of silicic acid can effectively be used as templates to prohibit the growth of MoS2.Analysis of TEM, Raman spectra, XRD and BET reveals that the added TEOS (the molar ratio of SiO2/MoS2=10.0) plays a vital role in forming of ultra-small exfoliated sheets and obtaining high specific surface area (101.6 m2/g) in the resultant products. The prepared exfoliated sheets of MoS2 were employed as counter electrodes (CEs) materials for dye-sensitized solar cells (DSSCs). The electrochemical analysis (cyclic voltammograms, electrochemical impedance spectroscopy) indicates that the porous MoS2 sheets CEs possess lower charge transfer resistance and a higher electro-catalytic activity in reducing I3- to I" compared to the flower-shaped MoS2 synthesized with less amount of the added TEOS. The DSSCs based on the porous MoS2 sheets CEs was demonstrated to achieve a high power conversion efficiency of 6.35% which is comparable to that of Pt CEs (6.19%).2. Leaf-shaped MoS2 nanosheets were for the first time prepared by H2SiO3 exfoliation by adding TEOS at the molar ratios (SiO2/MoS2) of 2.5. The prepared MoS2 nanosheets possess a high specific surface area of 37.8 m2/g, and present excellent UV-visible-NIR absorbance properties, and the absorption peaks of visible region are much higher than that of ultraviolet region. Therefore, they can be used as excellent catalysts for visible-light-driven degradation of methyl orange (MO). The effect of photo-degradation parameters of MO including pH value, dosage of catalyst and initial concentration was studied. The strongly acidic solution of MO facilitates producing free radicals of·OH in this catalytic system.3. Carbon nanotubes-MoS2-carbon (CNTs-MoS2-carbon) was synthesized via a method of wet impregnation and calcination with the assistance of surface-active polyethylene glycol 400 (PEG400). Characterizations of TEM, Raman spectra, XRD, XPS, BET and TG-DSC revealed that CNTs were homogenously coated with ultra-thin layers of MoS2. It was demonstrated that the unique structure is attributed to the wetting and emulsification capacity of PEG400. The CNTs-MoS2-carbon was used as counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). Analyses of electrochemistry indicate that the CEs modified by CNTs-MoS2-carbon have high activity and stability in the electro-reduction from I3- to I" due to the low charge transfer resistance. DSSCs based on CNTs-MoS2-carbon CEs were demonstrated to have a power conversion efficiency of 7.23%, which is higher than Pt CEs (6.19%).4. The pre-coated MoS2 on the surface of CNTs facilitates adsorption of silver ions, and can improve the load of silver on CNTs, The homogeneous CNTs-Ag was prepared by immersing CNTS-MoS2 into Ag+solution. XRD and XPS tests showed that the pre-coated MoS2on the surface of CNTs can react with Ag+ to form elemental silver in the Ag+ solution, and provides more active sites for Ag+ adsorption, so the silver granules on the prepared CNTs-Ag become denser. UV tests showed that the prepared CNTs-Ag has a strong absorption property for visible light. The antibacterial tests showed the products have excellent photocatalytic antibacterial property under the visible light.5. Considering that CNTs are commonly available, they can be used as the template of the synthesis of MoS2 nanotubes. Firstly, The homogeneous CNTS-MoS2 was prepared by wet impregnation and calcination with the assistance of PEG400. After the removal of carbon from the composite of CNTS-MoS2 using CO2 gas at 850℃, the MoS2 nanotubes were prepared. The advantage of the method is that the walls thickness of MoS2 NTs is controlled by adjusting the concentration of impregnation liquid ((NH4)2MoS4 solution).The tests including TEM and EDS showed that the adsorption properties of MoS2 nanotube are excellent for silver ions. XRD tests showed that silver ions can be reduced into elemental silver by MoS2 nanotubes and adsorbed on its surface, and also react with MoS2 to form Ag2S. |
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