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Graphene -based nano- composites and functional applications

Author: ZhouKangFu
Tutor: ZhuYiHua
School: East China University of Science and Technology
Course: Materials Science and Engineering
Keywords: Graphene Biosensor Solvothermal reaction Graphene composite material Class graphene
CLC: TB383.1
Type: PhD thesis
Year: 2012
Downloads: 1549
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Abstract

Graphene is sp2 hybridized carbon atoms form a two-dimensional single-atom layers, can be seen as a basic material composed of carbon family unit. Two-dimensional graphene structure and long-range π-electron conjugated given its unique thermal, mechanical, and electrical properties of graphene therefore theoretical research and practical applications in two aspects are of great value. In this paper, the existing biosensors electron transfer rate is slow, difficult to maintain enzyme activity and so on, through the introduction of gold particles having a graphene composite materials to promote the enzyme and the electron transfer between the electrodes and to maintain the catalytic activity of the enzyme, thereby enhancing the sensor performance. Meanwhile, to prepare a special functional graphene-based composite materials, paper and metal graphene oxide precursor was synthesized through Solvothermal graphene and graphene-Fe3O4-TiO2 composite materials, and the effects of its application performance. This chapter was prepared by chemical water-soluble graphene. First, a conventional method, and ultrasound obtained Hummers graphene oxide, the graphene oxide with hydrazine prior to the introduction of sulfonation step process, so that the resulting tape graphene sulfonic acid groups (-SO3-), and With this sulfonic acid group electrostatic repulsion between the role of the graphene achieve stable dispersion in water. This chapter obtained using a water-soluble graphene were built new graphene-based hydrogen peroxide sensor and a glucose sensor. (1) the graphene catalase HRP dispersed in chitosan solution was dropped onto the surface of glassy carbon electrode layer of uniform biofilm grown on the surface of the electrode by plating gold particles. Cyclic voltammetry show this electrode can achieve direct electrochemistry of HRP, and can electrocatalytic reduction of H2O2. This hydrogen peroxide biosensor response time less than 3s, the linear range from 5 × 10-6M to 5.13 × 10-3M, the detection limit is about 1.7 × 10-6M. (2) the graphene, previously prepared gold particles dispersed in the glucose oxidase together Nafion solution, and the mixture dispersed droplets onto the glassy carbon electrode surface constructed glucose biosensor. Hydroquinone present in the solution in the case, the electrode will have to join the glucose level a rapid response current, shows the typical catalytic oxidation of glucose. The linear range of the sensor from 15 × 10-6M to 5.8 × 10-3M, the detection limit is about 5 × 10-6 M. This chapter graphene oxide and a metal salt precursor was synthesized through solvothermal step graphene / metal oxide composite materials. (A) graphene oxide and ferric chloride as raw materials, through Solvothermal graphene / iron oxide composite material (G-Fe3O4). The temperature inside the reactor pressure environment containing group is decomposed is reduced graphene oxide graphene, while graphene oxide adsorbed on the surface of the iron ions generated in situ reaction of Fe3O4 particles. Fe3O4 size and distribution of the surface of the graphene material density can be adjusted in the concentration of Fe3. The resulting G-Fe3O4 at room temperature up to the saturation magnetization 45.5 emu g-1. G-Fe3O4 can be used to load and targeted drug delivery, G-Fe3O4 to doxorubicin saturated load factor reached 65% In G-Fe3O4 as the electrode material build-modified biosensor of hydrogen peroxide, but also has good performance. (2) to graphene oxide and tetrabutyl titanate as raw material, through Solvothermal graphene / titania composites (G-TiO2). The results showed that the anatase TiO2 particles uniformly distributed on the surface of the graphene and the average particle size. Compared with pure TiO2, G-TiO2 in the UV - visible absorption spectrum of the absorption edge of the apparent move to the visible region. G-TiO2 structure relies on the solvothermal reaction time, an appropriate extension of the reaction time can be beneficial and TiO2 is formed between the graphene chemical, to obtain a better combination, a more homogeneous dispersion of composite materials. Graphene can effectively prevent the introduction of electron-hole pairs TiO2 composite, which can be G-TiO2 to prove the fluorescence quenching. G-TiO2 methylene blue photocatalytic degradation activity but also with the raw material graphene oxide content related to optimal preparation conditions, the resulting G-TiO2, in the simulated sunlight irradiation, within three hours can catalyze the degradation of more than 75% methylene blue. The article also made some kind of graphene materials. In the fifth chapter, prepared by liquid-dimensional MOS2 films, to detect and block its fluorescence emission MoS2 completely different nature. By introducing Ag @ SiO2 shell composite material, the use of the mechanism of metal reinforcement can further improve the fluorescence-dimensional fluorescence intensity of MoS2.

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