Layers Of Self-assembly Techniques, Preparation Of Manganese Oxide / Graphite Oxide Thin Film Materials

In recent years, the research of the hybrid functional nanomaterials by a simple hybrid method has a potentional attention because the obtained hybrid functional nanomaterials show a particular chemical and physical property. The novel properties originated from the synergic effect between each component may compensate the drawback of single functional materials and create a new filed of material design. The inorganic layered materials have drawn much potential from both the fundamental and practical viewpoints, which can be delaminated its nanosheets. The obtained nanosheets show a characterization of signle crystallity and can be used to assemble multi-functional nanomaterials by using inorganic nanosheet assembling technology. A series of functional nanomaterials can be assembled in a favoruable condition.On the basis of the structure characterization and predominant performance of layered manganese oxide and graphite oxide, layered manganese oxide and graphite oxide were chosen as precursor, polyethylenimine as a linker, multilayer films of layered manganese oxide and graphite oxide were fabricated by a layer-by-layer method. The multilayer films are expected to apply to be used as electrode materials due to their electrical properties. This paper mainly consists of two sections, review and experiments. The development and application of graphite oxide, layered manganese oxide and LBL self-assembly technique were reviewed; and the main research work and purpose for this work were described in the review part (Chapter 1). The multilayer film materials have been synthesized using manganese oxide nanosheets and graphite oxide nanosheets as starting materials in experimental part. Meanwhile, electrochemical properties of the obtained multilayer films have also been researched (Chapter 2 and 3).The main research works were as follow:(1) Research on the fabrication of MnO₂/GO hybrid functional nanofilm. Firstly, the layered manganese oxide was prepared by using an oxidation-sedimentation under a hydrothermal condition, and GO was fabricated by a Hummer method from natural graphite power. When the layered manganese oxide and GO were soaked in a tetramethylammonium hydroxide aqueous solution for 7 days, the layered manganese oxide and GO were swelled and finial delaminated into manganese oxide nanosheet and GO nanosheet suspension, respectively, and the obtained inorganic nanosheets were also characterized. A quartz slide was firstly treated in an HCl/H₂SO₄ mixed solution. The treated quartz slide was immersed in a negatively charged solution of delaminated MnO₂ nanosheet suspension, a positively charged solution of PEI and followed in a GO nanosheet suspension, respectively, and MnO₂/GO hybrid functional nanofilm was fabricated via the layer by layer method. The multilayer film has a layered structure with a basal spacing of 0.74 nm. UV-vis absorption spectra of the obtained MnO₂/GO hybrid functional nanofilms with different deposited layers indicated that the equal adsorbort amounts of inorganic nanosheets could be assembled for each deposition cycle.(2) Under a assemble condition of fixing the adsorbort time and the concentration of GO nanosheet suspension, the effect of PEI concentration and the concentration change of GO nanosheet suspension on the assemble process of the hybrid functional nanofilm was systematically discussed. The results indicated that the adsorbort amount of nanosheets on the films was small and the distribution of nanosheets adsorbed became uniformity when the concentration of PEI and GO nanosheet suspension was low. The adsorbort amount of nanosheets on the films became equality and did not change with the deposited time when the concentration of PEI and GO nanosheet suspension reached a relative amount.(3) Electrochemical property of hybrid functional nanofilm was studied by a three electrode system. The experimental results showed that the obtained hybrid functional nanofilm showed a good capacitancer in 1mol/L Na₂SO₄ solution. Meanwhile, the obtained hybrid functional nanofilm also showed good reversibility and high power density in both different scan rates and different numbers of assembled nanosheet. The assemble way had a small influence on the capacitancer and the cycle property of the obtained hybrid functional nanofilm, but had a large influence for their position and magnitude of the redox peaks.The obtained hybrid functional nanofilms at different stages were characterized by XRD, FT-IR, UV-vis, TEM, SEM, AFM, contact angle measuring and electrochemical test.