Transition Metal Iron, Copper Oxide Nanomaterials Preparation And Catalytic Application Research

As we all known that materials may exhibit unique electronic, magnetic, optical properties, which is quite different from their bulk counterparts with large size, when their sizes decreased to nanoscale range (1-100nm). As one kind of the most important functional materials, transition metal oxide nanostructures have shown great application potential in many areas, such as data storage, separation science, catalysis science, energy exploitation, biomedicine, chemical sensor, microwave absorption, environmental protection, etc. Recently, the subject, focusing on synthesis, functionalization and applications of transition metal nanomaterials, has been a topic of great current interest. Based on the above context, here the following tasks have been designed and achieved in this theme:(1) Porous magnetite (Fe3O4) nanospheres consisting of primary nanocrystals have been synthesized through solvothermal method by using FeCl3·6H2O as the single iron resource, polyvinylpyrrolidone (PVP) as the capping agent and NaAc as the precipitation agent. The as-prepared porous Fe3O4nanospheres display excellent magnetic properties at room temperature. The factors including the concentration of the precursor, capping agent, precipitation agent, the reaction temperature and reaction time were investigated to understand the formation mechanism of the porous Fe3O4nanospheres. Catalytic activity studies confirm that as-prepared porous Fe3O4nanospheres have highly catalytic activity toward the degradation of xylenol orange (XO) in aqueous solution in the presence of H2O2. The results indicated that the as-prpepared porous Fe3O4nanospheres exhibit high catalytic performance toward degradation of XO with H2O2. It is characteristic of high reaction rate and high efficiency of decolorization. Meanwhile, the catalytic activity decreases only slightly after7cycles of the catalysis experiment.(2) Two iron oxides with different morphologies and sezes have been fabricated in aqueous solution with FeCl3·6H2O serving as the single iron resource by adjusting the amount of NH2NH2·H2O under hydrothermal condition. The effect of NH2NH2·H2O concentration on the phase and morphology of the product was systematically investigated. The chemical oxidation degradation of methylene blue with H2O2was chosen as a probe reaction to test the catalytic activity of the obtained iron oxide nanomaterials in this chapter. It was found that Fe3O4nanostructures exhibit higher activity a-Fe2O3. The differences of their catalytic activities were analyzed in terms of morphology effect as well as size effect. Furthermore, taking into accountant of the magnetic property of Fe3O4nanostructures, we systematically investigated the relationship between the catalytic activity toward the oxidation degradation of MB with H2O2and the morphology. The survey result these Fe3O4nanostructures all exhibited good catalytic performance. Fe3O4nanostructures with1-dimensional nanostructure, obtained when0.6mL NH2NH2·H2O was used, showed the most excellent catalytic property.(3) One kind of bifunctional magnetic nanocomposites:Fe3O4@PANI with well-defined core/shell structures, were obtained by means of the in-situ chemical oxidative polymerization of aniline monomer in the presence of the pre-synthesized Fe3O4nanoparticles using dodecyl sulfate (SDS) as the dopant. The resultant nanocomposites not only have magnetism of Fe3O4nanoparticles which lies in the core layer of the nanocomposites but also have good electric conductivity. Furthermore, a novel type of Fe3O4@PANI nanocomposites modified glass carbon electrodes (Fe3O4@PANI/GCE) was fabricated and the electrochemical behaviors of N-acetyl-p-aminophenol (4-acetamidophenol, APAP) were studied on the Fe3O4@PANI/GCE. Fe3O4@PANI nanocomposites showed an excellent electro-catalytic activity for the oxidation of APAP and accelerated the electron transfer between the electrode and APAP.(4) Fe3O4@C nanocomposites with core@shell structure were synthesized via a two-step hydrothermal process. And then the supported Pd nanoparticle catalyst (Pd/MFC) was fabricated through in-situ reduction-precipitation method using Fe3O4@C nanocomposites as support. The morphology, inner structure, and magnetic properties of all products were studied with transmission electron microscopy, X-ray powder diffraction, Fourier translation infrared spectroscopy, X-ray photoelectron spectroscopy, and vibrating sample magnetometer. The Suzuki and Heck coupling reactions were used to demonstrate the catalytic efficiency of the as-prepared Pd/MFC nanocomposite catalyst. The results showed that the catalyst is completely recoverable with the simple application of an external magnetic field, and the catalytic efficiency shows no obvious loss for Suzuki and Heck coupling reactions even after5repeated cycles.(5) Here, an efficient hydrothermal procedure for the fabrication of CuO nanostructures with rod-like shape by using trisodium citrate as the structure directing reagent and NaOH as mineraizer. The effect of trisodium citrate on the morphology and size of the product was investigated. In addition, the application of catalyzing oxidation of two olefins (cyclohexene and styrene) was studied using the as-prepared CuO nanorods as catalysts. The result revealed that cyclohexene could be completely converted into2-cyclohexene-l-one by tert-butyl peroxide (TBHP) in CH3CN in the presence of CuO nanorods. As for oxidation of styrene, the main products are styrene epoxide and benzadehyde, and their selectivities are related to the experimental parameters including the oxidant as well as its concentration, reaction temperature. Such exciting conclusions indicate that the CuO nanorods obtained through procedure developed here might be one of the most excellent candidates to catalysts, which are used for directly synthesizing α,β-unsaturated ketones and styrene epoxide/benzadehyde from their corresponding olefins.