Synthesis And Properties Of ZnO-based Nanomaterials

Nanomaterials and composites based on ZnO show unique structure and special properties, which have been widely used on optical, magnetism, photocatalysis, and sensors. Researchers have paid attention to synthesis a kind of materials with efficient properties via economic and facile method for a long time. In this dissertation, different materials based on ZnO have been synthesized by chemical precipitation and hydrothermal methods and their potential applications have also been investigated in the field of water treatment and environment protection.The main research contents of this dissertation are as follows:1. Synthesis of AgBr-ZnO nanocomposites and their photocatalytic propertyIn this process, ZnCl2 was used as precursor, NaBH4 as reducing agent and alkaline medium, CTAB as surfactant and Br source, and distilled water as solvent. Then a certain amount of AgN03 was added. The typical products were obtained at 80 ℃. The structure and phase of the synthesized samples were characterized by X-ray diffraction (XRD), field-emission scaning electron microscopy (SEM) and transmission electron microscopy (TEM), and so on. The results showed that the synthesized samples were shuttle-like ZnO decorated with AgBr nanoparticles. BET results indicated that specific surface area of as-prepared compound was lager than that of ZnO. Interestingly, the synthesized AgBr-ZnO nanocomposites displayed efficient phtocatalytic property for the decomposition of RhB.2. Synthesis of ZnFe2O4 nanoparticles and their gas sensing propertyBased on our previous work, FeCl3 and freshly prepared ZnO being used as precursor, N2H4·H2O as reducing agent, ZnFe2O4 nanoparticles were synthesized via a hydrothermal route. The phase and morphology of the synthesized samples were also investigated by XRD, TEM, X-ray photoelectron spectroscopy (XPS), and so on. The results revealed that the typical products are ZnFe2O4 nanoparticles with diameter of ca.10 nm. The magnetic test result indicated that the products have a strong paramagnetism, which is convenient for the sample collection and recycling. Meanwhile, the large special surface area of the sample was beneficial for the improvement of gas sensing property. Importantly, ZnFe2O4-based gas sensors have been fabricated and gas sensing property of several common compounds, such as acetone, ethanol, methanal, isopropanol, ethyl acetate have been detected. Results show that ZnFe2O4-based gas sensors displayed high efficient selectivity and superior response for acetone gas.3. Synthesis of Co0.85Se-ZnO nanocomposites and their catalytic propertyBased on our previous report about Co0.85Se thin film, Co(NO)3-6H20, Na2SO3 and Zn(NO3)2·6H2O were used as precursors, N2H4·H2O as reducing agent and distilled water as solvent, Co0.85Se-ZnO nanocomposites were synthesized via hydrothermal method. The phase and morphology of the synthesized samples were also investigated by XRD, TEM, XPS, and so on. A series of characterizations indicated that the mole ratio of reactant played important role on the phase and morphology of the synthesized samples. The typical products are Co0.85Se thin film decorated with ZnO nanoparticles. The large specific surface area can provide more reactive sites for the following catalytic experiments. The Co0.84Se-ZnO nanocomposites were used as catalysts for the decomposition of N2H4·H2O and showed high catalytic efficiency and reusability.