Preparation Of Graphite, Nickel - Aluminum Hydrotalcite Two - Dimensional Materials And Its Application In Electrorheological, Anticorrosion And Biomimetic Imaging

Recently, two-dimensional nano-materials especially graphene and layered double hydroxide are being studied for their potential physical properties. It is found that graphene has electron mobility that exceeds 15,000 cm2 V-1 s-1 at room temperature, extremely low electrical resistance(10-6 Ω·cm), high transparency(absorbing only 2.3% of light), and excellent thermal conductivity(5300 W m-1 K-1). The layered double hydroxides(LDH) are hydrotalcite-like clays with the empirical formula, [MII1-xMIII x(OH)2]x+[An- ]x/n·mH2O, where MII and MIII are divalent and trivalent metals such as Mg, Ni, Co, Al, and Fe, An- can be almost any anion with the charge number of n. Due to their special and complicated structure and anion exchange property, LDH materials have been applied to many areas including catalysts, anion exchangers, electrodes for alkaline secondary batteries and supercapacitor.1. The core-shell structured SiO2@Ni-Al layered double hydroxide(LDH) composites were prepared via self-assembly of Ni-Al LDH on the surface of SiO2 spheres. Only coating a layer of ultrathin Ni-Al LDH sheet, the resulting SiO2@Ni-Al LDH composites exhibit significantly enhanced electrorheological(ER) characteristics compared to conventional bare SiO2 spheres. The monodispersed SiO2 spheres with average diameters of 260 nm were synthesized by the hydrolysis of tetraethyl orthosilicate(TEOS), while the shell part, Ni-Al LDH sheet was prepared by the hydrothermal procedure. The morphology of the samples was investigated via scanning transmission electron microscopy(STEM), scanning electron microscopy(SEM) and transmission electron microscopy(TEM). The structure of the samples was characterized by X-ray diffraction(XRD). The species and distribution of elements in samples were confirmed by X-ray photoelectron spectroscopy(XPS), Energy dispersive analysis of X-ray(EDX) and elemental mapping in STEM. Subsequently, the ER characteristics of the composites dispersed in insulating oil were characterized by a rotational rheometer. The electric field-stimulated rheological performances(yield stress, viscosity, modulus, etc.) were observed under an external electric field, which is different from the Newtonian state in the free electric field.2. In the present work, ion beam sputtering deposition(IBSD) was used to sputter the graphene nanodots onto the steel for enhanced anticorrosion properties. Various graphene nanodots coated steel samples were prepared by changing the IBSD time, and the inhibition efficiency of graphene nanodots coated steel can reach 91.28%. With the graphene protective barrier, the corrosion rate(CR) of the steel thin film in salt solution is reduced by 12.76 times, 0.00138 mm/year better than 0.019 mm/year for the bare steel. In addition, it’s also found that samples with 60 nm thickness of graphene nanodots coating have the saturate anticorrosion rate. The formation of the graphene coated steel was also investigated using scanning electron microscope(SEM), transmission electron microscope(TEM) and X-ray photoelectron spectra(XPS). This graphene anticorrosion structure may envision some promising applications in steel industry.3. Graphene quantum dots(GQDs) has been prepared by oxidation-hydrothermal reaction, using ball milling graphite as the starting materials. The prepared GQDs were endowed with excellent luminescence properties, with the optimum emission of 320 nm and 260 nm, blue photoluminescent(PL) emitted from the GQDs was clearly shown under ultraviolet light. The GQDs were 3 ? 0.2 nm in width and 0.5-2 nm in thickness, revealed by high-resolution transmission electron microscopy(HRTEM) and atomic Force Microscopy(AFM). In addition, Fourier transform infrared spectroscopy(FT-IR) testing showed the existence of carbonyl and hydroxyl groups, meaning GQDs can be dissolved in water easily and used in cellar imaging, and blue area inside L929 cells were clearly observed under the fluorescence microscope. Both low price of raw material and simple prepared method will contribute to the high quality GQDs widespread application in future.