超轻多功能石墨烯复合海绵的制备及其应用研究

发布时间：2018-06-18 16:44

本文选题：石墨烯 + 功能填料　；参考：《哈尔滨工业大学》2016年博士论文

【摘要】：石墨烯海绵是基于石墨烯纳米片构成的三维多孔材料,它具有超轻密度、高孔隙率、高比表面积等特点,因此在石墨烯材料中备受关注。大量的研究表明石墨烯海绵在能源、环境、电子等领域中有着良好的应用价值。此外,三维石墨烯海绵比二维石墨烯纳米片更容易操控,是将石墨烯的优良性能应用在实际领域中的一种有效途径。本论文主要研究三维石墨烯海绵的不同制备方法及其带来的结构变化对海绵综合性能的影响。通过引入不同的功能填料后,根据不同的制备方法能够得到不同结构的三维石墨烯海绵,而这些结构以及功能填料的种类赋予复合海绵不同的性能,所制备的海绵不仅都能够作为超级电容器电极,还能够根据自身结构特点应用在其他领域中,因而具备多功能性的特点。首先对结构、性能与石墨烯最相近的石墨烯纳米带作为功能填料进行了研究。我们将其与石墨烯片复合,利用直接冷冻干燥的方法制备成高孔隙率、超低密度、具有优异压缩性和弹性的复合海绵。该复合海绵由石墨烯复合纳米片相互搭接构成,在海绵内部结构中,由于范德华力及碳碳双键的相互作用,石墨烯纳米带紧紧的吸附在石墨烯片表面组成了该复合海绵的孔壁,从而提高了海绵的力学强度。将复合海绵作为超级电容器的电极,其比电容最高能够达到256 F g~(-1),引入导电聚合物聚吡咯后形成的石墨烯纳米带-石墨烯-聚吡咯三元体系复合海绵的比电容可以进一步提高至537 F g~(-1)。大孔结构、稳定的性能使得复合海绵还具有较高的吸附有机溶剂及油剂性能(吸附量从100到350 g g~(-1)),可以作为水处理材料。基于上述研究结果,为了一进步提高复合海绵的力学强度,我们设计了另一种通过“浸渍-还原”法制备的以碳化纤维作为三维骨架的石墨烯海绵。该复合海绵以纤维素组成的三维材料(烟头)作为模板,通过浸泡在氧化石墨烯溶液中,随后高温还原的方法制备得到。该复合海绵具有超轻密度(ρ=7.6 mg cm-3)的同时却具有较高的力学强度,其最大压缩强度高达0.07 MPa,且能够承受自身质量4000倍的重物。海绵内部结构是由石墨烯纳米片包裹的碳化纤维相互交织缠绕,进而组成了三维多孔结构,将其组装成超级电容器后,比电容为28.9 F g~(-1);该海绵独特的结构使得其在电磁波吸收领域中具有出色的表现:其有效电磁波反射损耗(~(-1)0 d B)带宽能够达到4.1 GHz,最高反射损耗值高达-30.53 d B;引入导电聚合物聚吡咯以后,三元体系的复合海绵压缩强度进一步提高到0.09MPa,电磁波反射损耗值提升至-45.12 d B。改变制备的方法,通过引入尿素与纤维素在高温条件下发生反应,能够制备出氮掺杂石墨烯“接枝”在碳化纤维上的复合海绵。该复合海绵是由氮原子掺杂的石墨烯“生长”在碳化纤维上,再通过碳化纤维相互缠绕构成了三维多孔结构。由于杂原子的引入,该碳化纤维增强的石墨烯复合海绵电容性能得到提高,将其组装成超级电容器后,比电容值能够达到107.5 F/g~(-1)。此外,这种“接枝”的结构也使得该碳化纤维增强复合海绵具有优异的弹性性能,压缩形变达到60%时仍能完全弹性恢复;而多孔结构、亲油疏水的特点使其成为一种理想的吸附材料。除了引入碳材料以外,我们还提出了通过“电化学沉积-浸渍-还原”法制备一种尚未见报道的、以三维聚吡咯作为骨架的石墨烯复合海绵。首先将镍泡沫作为模板,通过电化学沉积的方法将聚吡咯沉积在镍泡沫上,将基底刻蚀掉得到柔性的三维聚吡咯骨架。该骨架独特的结构,使其除了能够作为制备石墨烯复合海绵的基底,还能够直接作为压力传感器电极、超级电容器电极等;通过“浸渍-还原”的方法,将石墨烯涂覆在该骨架的表面,我们制备了区别于传统结构的新型聚吡咯增强石墨烯复合海绵,该复合海绵的拉伸强度为200 k Pa,将其作为压力传感器电极进行测试,结果显示器件具有良好的电信号响应;此外,该复合海绵还是一种优异的超级电容器电极材料,通过三电极体系测试可知单电极比电容高达702.9 F g~(-1),组装成器件后,相应的超级电容器比电容值高达357.5 F g~(-1),且具有良好的循环使用性能,经过5000次充放电循环后,电容器的比电容保持率仍达到82%。
[Abstract]:Graphene sponge is a three-dimensional porous material based on graphene nanoscale. It has the characteristics of ultra light density, high porosity, high surface area and so on. Therefore, it has attracted much attention in graphene materials. A large number of studies have shown that graphene sponge has good application value in energy, environment, electronics and other fields. In addition, three-dimensional graphene sponge. It is an effective way to apply the excellent properties of graphene in practical fields than the two-dimensional graphene nanometers. This paper mainly studies the different preparation methods of the three-dimensional graphene sponge and the effect of the structural changes on the comprehensive performance of the sponge. The method can obtain three-dimensional graphene sponges with different structures. These structures and the types of functional fillers give different properties to the composite sponge. The sponge prepared not only can be used as the electrode of the supercapacitor, but also can be applied in other fields according to its own structure characteristics. We have studied the graphene nanoribbons with the most similar graphene as functional fillers. We compounded it with Shi Moxi to prepare a composite sponge with high porosity, ultra-low density and excellent compressibility and elasticity by direct freeze-drying. The composite sponge is made up of graphene composite nanoscale with each other, in the sea. In the internal structure, due to the interaction of van Edward force and carbon carbon double bonds, the graphene nanoribbons tightly adsorb on the surface of the graphene sheet to make up the pore wall of the composite sponge, thus improving the mechanical strength of the sponge. The composite sponge as the electrode of the supercapacitor can reach the highest specific capacitance of 256 F g~ (-1) and introduce conductive polymerization. The specific capacitance of the composite sponges of the graphene nanband - graphene polypyrrole three element system after the compound polypyrrole can be further improved to 537 F g~ (-1). Large pore structure and stable properties make the composite sponge also have high adsorption organic solvent and oil properties (adsorption capacity from 100 to 350 g g~ (-1)), which can be used as a water treatment material. In order to improve the mechanical strength of the composite sponge in order to improve the mechanical strength of the composite sponge, we designed another kind of graphene sponge prepared by the "impregnation reduction" method with carbonized fiber as a three-dimensional skeleton. The composite sponge is made of a three-dimensional material of cellulose (cigarette) as a template, and then soaked in the solution of graphene oxide. The composite sponge has a super light density (P =7.6 mg cm-3) and a high mechanical strength. The maximum compressive strength is up to 0.07 MPa, and it can withstand the weight of 4000 times of its mass. The internal structure of the sponge is interwoven with graphene nanoscale carbon fibers, and then compose. After the three-dimensional porous structure is assembled into a supercapacitor, the specific capacitance is 28.9 F g~ (-1); the unique structure of the sponge makes it excellent in the field of electromagnetic wave absorption: its effective electromagnetic wave reflection loss (~ (-1) 0 d B) bandwidth can reach 4.1 GHz, the highest reflection loss value is as high as -30.53 D B; the conductive polymer polypyrine is introduced. After that, the compression strength of the composite sponge in the three element system is further improved to 0.09MPa. The reflection loss value of the electromagnetic wave is raised to -45.12 D B. to change the preparation method. By introducing the reaction of urea and cellulose under the high temperature condition, the composite sponge with nitrogen doped graphene "graft" on the carbonized fiber can be prepared. The nitrogen atom doped graphene "grows" on the carbonized fiber and then intertwine with the carbon fiber to form a three-dimensional porous structure. Due to the introduction of the heteroatom, the carbon fiber reinforced graphene composite sponge has improved the capacitance performance. After assembling it into a supercapacitor, the specific capacitance can reach 107.5 F/g~ (-1). Besides, the capacitance of the carbon fiber reinforced graphene composite sponge can be reached. This "graft" structure also makes the carbonized fiber reinforced composite sponge with excellent elastic properties, and the compression deformation is still fully resilient when the compression deformation reaches 60%, while the porous structure, the characteristics of hydrophobic and hydrophobicity make it an ideal adsorption material. Besides the introduction of carbon materials, we also put forward by "electrochemical deposition leaching". A new type of graphene composite sponge, which has not been reported, is prepared with three dimensional polypyrrole as a skeleton. First, the nickel foam is used as a template. Polypyrrole is deposited on the nickel foam by electrochemical deposition, and a flexible three-dimensional polypyrrole bone frame is obtained by etching the substrate. In order to prepare the substrate of the graphene composite sponge, it can be directly used as the pressure sensor electrode, supercapacitor electrode and so on. Through the "impregnation reduction" method, the graphene is coated on the surface of the skeleton, and a new polypyrrole reinforced graphene composite sponge, which is different from the traditional structure, is prepared. The tensile strength of the composite sponge is 2. 00 K Pa is tested as a pressure sensor electrode, and the display device has a good electrical signal response. In addition, the composite sponge is an excellent supercapacitor electrode material. Through the three electrode system test, the single electrode specific capacitance is up to 702.9 F g~ (-1), and the corresponding supercapacitor is compared to the capacitance after assembly. The value is as high as 357.5 F g~ (-1) and has good cycling performance. After 5000 cycles of charge and discharge, the specific capacitance retention rate of the capacitor is still 82%..
【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TQ127.11;TM53

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