基于石墨烯凝胶材料的辐射制备及其应用研究

发布时间：2018-04-06 20:32

本文选题：伽马射线　切入点：氧化石墨烯　出处：《中国科学技术大学》2017年博士论文

【摘要】：基于石墨烯的凝胶材料具有优异和独特的化学和物理性能,在吸附、催化和传感器等领域有着广泛的应用前景。目前,虽然有多种方法能有效实现基于石墨烯的凝胶材料的制备,如水热法、化学还原法和模板法等,但是通常需要高温高压、添加还原剂或者模板等条件。因此,也带来了高成本和污染等问题,不利于基于石墨烯凝胶材料的大规模生产和实际应用。本论文从氧化石墨烯(GO)的醇水分散体系出发,利用γ射线辐射一步实现GO的还原和功能化,并进一步自组装得到自支撑基于石墨烯的凝胶材料,并对其形成机理以及在吸附和电化学领域的应用进行了研究。主要研究成果如下:1.对分散在多种脂肪醇-水溶液中的GO纳米片的丫射线辐射还原改性和自组装行为进行了研究,详细探究了醇-水溶液的pH值、醇-水的体积比(φa/w)、醇的种类、GO浓度和吸收剂量等因素对3D大孔还原氧化石墨烯(rGO)水凝胶形成过程的影响。结果表明在醇-水溶液中,γ射线辐射将同时引发GO的还原和表面羟烷基链改性,此过程是控制GO纳米片自组装行为的关键。在强酸性条件(pH ≤ 2)下,表面羟烷基链改性的rGO纳米片通过疏水作用和氢键作用自组装形成自支撑3D大孔石墨烯水凝胶(SGH),经冷冻干燥后,得到低密度(4mg/cm3)的石墨烯气凝胶(SGA)。由于所制备的SGA是由表面羟烷基化的rGO纳米片构成,使得其对大多数极性和非极性有机溶剂(如DMF、甲苯、氯仿等)都具有很好的吸收性能,尤其是对醇类分子(吸收量147 g/g)。这一结果意味着本方法制备的SGA材料有望用于多种有机物的吸附分离。2.与异丙醇类似,叔丁醇也能有效清除HO·和H·,但文献中却报道γ射线辐照对分散在叔丁醇-水溶液中的GO纳米片几乎没有明显的还原作用。本论文考察了 GO的叔丁醇-水分散液在多种辐照条件下的产物形貌,发现在合适的辐照条件下,在叔丁醇-水溶液中同样能够得到自组装形成的SGH。通过SEM、FT-IR和Raman光谱以及XPS等表征方法,证明构成SGH的GO纳米片已发生部分还原,同时修饰上了叔丁醇分子。同样地,叔丁醇-水溶液中SGH的形成也需要在强酸性条件下才能形成。这个结果进一步证实了 GO纳米片在醇水溶液中的γ射线辐射效应表现为部分还原和羟烷基化,其程度和速度受到体系pH值,醇的浓度和分子结构、GO浓度和辐照条件(吸收剂量率和吸收剂量)的影响,最终决定了GO纳米片在辐照过程中的自组装行为。3.在上述γ射线辐射引发GO在醇水溶液中自组装机理的指导下,我们将H2PtCl6分散在GO的醇-水分散液中,通过γ射线辐射,在GO纳米片进行自组装的同时,进行H2PtCl6的辐射还原形成Pt纳米粒子,一步得到了负载Pt纳米粒子(粒径为1-5nm)的SGH (SGH-Pt)。经冷冻干燥后,得到负载Pt纳米粒子的SGA (SGA-Pt),并作为电容器电极材料考察了其电化学性能。研究结果表明,Pt纳米粒子含量为41%时,比电容达到206.8 F/g,经过4500次充放电循环后,比电容保留了 98 %。这说明所制备的SGA-Pt具有足够高的比电容和优异的循环稳定性,有望用做超级电容器的电极材料。4.分别将导电聚合物单体吡咯(Py)和3,4-乙撑二氧噻吩(EDOT)溶于GO的醇-水分散液中,首次利用γ射线辐射的方法,同步实现GO自组装和单体的辐射聚合,一步得到导电聚合物/石墨烯复合凝胶(CP-GH),并通过红外光谱、XPS、SEM、TEM和Raman光谱等对其化学结构和形貌进行了表征,并对单体的聚合机理进行了探讨。结果表明,在辐照过程中,GO纳米片的还原和自组装并没有受到单体以及所生成的聚合物的影响,而单体聚合生成的导电聚合物则负载在rGO骨架上。对聚吡咯-GO复合凝胶(PPy-GH)的电化学性能研究发现,Py加入量较少时(5和10μL)所制备出来的复合凝胶的充放电循环性能相对稳定,而在Py加入量较多时(20 μL)其充放电循环性能出现异常不稳定的现象。这可能是过量的Py单体导致聚合不充分造成的。本工作对于导电聚合物/石墨烯材料的高能辐射制备具有很好的指导意义。
[Abstract]:With excellent and unique chemical and physical properties, gel materials based on graphene in adsorption, catalysis and sensors and other fields have a wide application prospect. At present, although there are many kinds of methods can effectively achieve the gel material of graphene based preparation, such as hydrothermal method, chemical reduction method and template method, but usually requires high temperature and high pressure, adding a reducing agent or template condition. Therefore, brings high cost and pollution problems, the mass production of graphene gel materials and application based on not conducive to. In this thesis, graphene oxide (GO) alcohol aqueous dispersions of the gamma ray step to achieve the reduction of GO and the function of radiation, and further self-assembled gel material graphene based on self support, and the forming mechanism and application in adsorption and electrochemical field were studied. The main research results are as follows: 1. points Bulk reduction modification and self-assembly behaviors were studied in Ya radiation of various alcohols - GO nanoplates in aqueous solution, detailed study of alcohol water solution pH, ethanol and water volume ratio (a/w), alcohols, GO concentration and dose factors such as oxygen reduction of fossil graphene on 3D macroporous (rGO) hydrogel formation. The results showed that in ethanol water solution, gamma ray radiation will also lead to modification of alkyl chain reduction and surface hydroxyl of GO, this process is the key to control the self-assembly behavior of GO nanosheets. In strong acidic condition (pH = 2) under the surface hydroxyl, alkyl chain modified nano rGO by the hydrophobic interaction and hydrogen bond self-assembly to form free-standing graphene 3D macroporous hydrogels (SGH), after freeze-drying, low density (4mg/cm3) of the graphene aerogel (SGA). The prepared SGA is composed of rGO nano film the surface of Hydroxyakylation, making it Most of the polar and non-polar organic solvents (such as DMF, toluene, chloroform) has good absorption properties, especially for alcohol molecules (uptake 147 g/g). This result means that the preparation method of SGA material is expected to be used for.2. adsorption and separation of many organic compounds with similar isopropanol also, tert butanol can effectively remove HO and H, but was reported in the literature of gamma ray irradiation on dispersion of nano GO in TERT butanol aqueous solution almost no reduction effect. This paper examines the product morphology of GO TERT butanol water dispersion in various irradiation conditions, found in the irradiation under the suitable conditions, the same can self assemble to form the SGH. obtained by SEM in TERT butanol aqueous solution, FT-IR and Raman spectra and XPS spectra. The composition of nano GO SGH that has occurred at the same time on the part of reduction, modified molecular butanol. Likewise, tert butyl Alcohol formation in aqueous solutions of SGH also need to form in acidic conditions. This result further confirmed the effect of gamma ray radiation in alcohol aqueous solution of GO nano films showed partial reduction and hydroxyalkylation, its extent and velocity by the pH value of the system, the alcohol concentration and molecular junction structure, concentration of GO and irradiation conditions (absorbed dose rate and dose effect) the final decision of the GO nanosheets during irradiation the self-assembly behavior of.3. in the gamma ray radiation induced self-assembly mechanism of GO in alcohol water solution under the guidance, we will H2PtCl6 dispersed in GO alcohol aqueous dispersion, by gamma radiation, self assemble in GO nanosheets, radiation reduction of H2PtCl6 formed Pt nanoparticles, one step has been supported Pt nanoparticles (diameter of 1-5nm) SGH (SGH-Pt). After freeze-drying, the supported Pt nanoparticles (SGA-Pt SGA), And as a capacitor electrode material on its electrochemical performance. The results show that the Pt nanoparticles content is 41%, the specific capacitance reaches 206.8 F/g, after 4500 cycles, the specific capacitance retained 98. It shows that the prepared SGA-Pt has high specific capacitance and good cycle stability, is expected to used as electrode material for super capacitor.4. are conducting polymer monomer of pyrrole (Py) and 3,4- two oxygen ethylene thiophene (EDOT) dissolved in GO alcohol aqueous dispersion method, gamma ray radiation is used for the first time, synchronization of radiation GO self-assembly and monomer polymerization step by conductivity the polymer / graphene composite gel (CP-GH), and through the infrared spectrum, XPS, SEM, the chemical structure and morphology were characterized by TEM and Raman spectra, and the mechanism of polymerization of monomer were discussed. The results show that in the process of radiation, GO nanosheets and reduction Self assembly has not been affected by the monomer and polymer, and the monomer polymerization of conductive polymer generated is loaded in the rGO skeleton. Of the PPy / -GO composite gel (PPy-GH) electrochemical performance study found that the amount of Py is small (5 and 10 L) in the preparation of the composite gel the charge discharge cycle performance is relatively stable, but when the Py content is more (20 L) and the charge discharge performance of the abnormal unstable phenomenon. This may be an excess of Py monomer to polymerization is not sufficient cause. This work for the preparation of conductive polymers has a good guide for graphene high-energy radiation the material.

【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TQ127.11;O648.17

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