| Low-dimensional structure such as one-dimensional fibers, nanorods, nanotubes and other morphology, a system which contains a variety of interesting chemical and physical phenomena, has long been a popular research field. Since single material cannot break through restrictions of their own performance, effective integration and assembly are effective ways to break through the restriction. This paper focuses on ordered assembly and controlled synthesis of graphene and TiO2 nanowires, to obtain a novel class of two-dimensional reduced graphene oxide (RGO)/titanate nanowire mesh filters, which exhibits excellent performance to adsorb pollutions in water in a continuous flow reactor,. Also, another novel one-dimensional RGO/TiO2 nanowires is controllably synthesized in this article. We innovatively carried out some exploratory research on the electrical properties of a single nanowire. The main content is listed below:(1) The size of GO, which was prepared by modified Hummers’ method, has been precisely controlled from 2.3 μm to 0.5 μm or less by sonication. However, when the sonication time increased to 32 min, GO was undesirably reduced to RGO. Therefore, this article optimized the sonication time to 16 min, when GO size is less than 0.5 μm. At this time, GO maintained the oxidation state, which facilitates following assembly work with TiO2.(2) Using P25 as precursor to synthesize controlled titanate nanowires by hydrothermal method, the growth mechanism is listed as follow:ⅰ) in the hydrothermal reaction, maturation first occurs in TiO2 particles, which means the smaller size of the particles gradually dissolve while the larger particle size particles gradually grow. In the meantime, H2O and OH- in NaOH solution access into the TiO2 lattice between titanium atoms and react with the oxygen atoms, a hydroxyl group generated titanium, resulting in crisp porous TiO2 particles, and gradually form a porous large diameter balls.ⅱ) As the reaction proceeds, since the effect of intercalation of Na +ions to generate sodium titanate, sodium titanate nanoribbons is formed in the surface of the spherical particles, continuous sheet extending outwardly growth, eventually leading to the collapse of the sphere, finally only sodium titanate nanoribbons remained.ⅲ) With the mechanism of Splitting Model, sodium titanate sheet separate and occurs to form ordered nanowire bundle form, after ultrasonic dispersion, harness nanowires separated, forming nanowires. In addition, by fine regulation of the alkali species of hydrothermal reaction, hydrothermal time and pickling conditions, four different morphologies titanate nanomaterials have been synthesized:porous nanospheres, nanoribbons, nanowires, nanotubes. In accordance with different proportions graphene in different sizes and sodium titanate nanowire in different morphologies composite, we composites "sea urchin-like", "intertwined membranous" titanate nanotubes and graphene oxide orderly interwoven like complexes.(3) Using titanate nanowires and GO to make two-dimensional RGO/titanate nanowires mesh membrane under controllable assembly condition. The assembly mechanism are:ⅰ) under the action of non-covalent bond, especially in the van der Waals force, GO would attack titanate nanowires;ⅱ) GO spontaneously curled up, covering in a root or more adjacent root titanate nanowires surface;ⅲ) after adding hydrazine hydrate, GO is restored to RGO, in order to reduce the surface free energy, RGO in different nanometer line attract each other, RGO which is in the node would attract more free RGO which is in the solution to surface, thickening of the junction of RGO, crosslinking more firmLy. In the end, two-dimensional RGO/titanate nanowires mesh membrane are formed.(4) A novel microfiltration film forming apparatus has been designed, composed by syringe, micro-injector, and filter head components. Fine forming process by regulating flow rate, volume, pressure, and time variables titanate nanowires and RGO film assembly build fast and evenly. With this preparation device, two dimensional RGO/titanate nanowire mesh membrane surface will be smooth, uniform color, and can be self-supporting, and even after repeated bending, membrane structure remains intact. Rhodamine B solution chosen as a model, RGO/titanate nanowire membranes, bleaching rate of more than 98%, can efficiently remove organic contaminants in aqueous solution. Among them, the titanate nanowires role as a skeleton supporting graphene and be effective way to avoid the graphene reunion. Bare graphene has rich adsorption active sites, showing efficient adsorption. The filter with the adsorption saturation can also obtained regeneration, by using hypochlorous acid solution to remove organic matter adsorbed.(5) The RGO/TiO2 nanowires were composited by electrospinning. A single fiber of RGO/TiO2 nanowires electrical test platform was built in a chamber of transmission electron microscope (TEM), using in situ electrical characterization techniques to measure a single fiber rectifying curve successfully. With energizing for many times, variation law of nanowire microstructure is observed. This is very meaningful for the latter part of the study, especially in the electrical properties of one-dimensional fiber data analysis. |
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