超临界二氧化碳协助制备多组分复合材料及在超级电容器方面的应用

Fabrication of hierarchical nanohybrids with assistance of supercritical CO_2 for high-performance supercapacitor applications

采用绿色水热方法合成石墨烯/吡咯气凝胶(G-Py),原位聚合的方法制备碳纳米管/聚苯胺复合材料(CNT/PANI),而后通过超临界二氧化碳的协助制备了一系列G-Py和CNT/PANI的复合材料,并通过红外光谱(FTIR)、X射线衍射(XRD)和Raman光谱研究其结构变化,电化学工作站测试其电性能,从而探究超临界二氧化碳对其结构和性能的影响.研究结果表明,经过超临界二氧化碳协助一步法得到的复合材料具有最优的电性能.电化学测试表明其比电容高达373 F/g,是未经超临界二氧化碳处理制备的复合材料的1.4倍,说明超临界二氧化碳辅助制备是构筑多组分复合材料的一种有效方法.

Graphene, a novel one-atom-thick two-dimensional （2D） nanomaterial, has attracted much attention, owing to its outstanding chemical and physical properties. In order to expand the application of graphene-based materials in environment, energy, biological and sensing fields, it is necessary to assemble 2D graphene sheets into three-dimensional （3D） architectures. It may furnish graphene materials with higher specific surface areas, stronger mechanically strengths and faster mass and electron transport kinetics because of the combination of 3D porous structure and the outstanding intrinsic properties of graphene. Building 3D graphene-based hybrid nanostructures with anticipated function has become one of the most active research fields. Considering the single-phased nanomaterials always have their intrinsic defects, scientists are inclined to combine unique properties of individual nanostructures and explore their synergistic effect. Considering its low viscosity, high diffusivity, zero surface tension, and plasticization to polymer, supercritical CO2 （scCO2）has been applied in the fabrication of nanomaterials. In view of the soft matter theory and the great tunabililty of scCO〉 it is anticipated that nanocomposites of tailored structure and controlled assembly of nanoparticles can be achieved with the help of scCO2. Graphene-pyrrole （G-Py） aerogel was prepared by a green hydrothermal route, while carbon nanotube/polyaniline （CNT/PANI） composite dispersion was obtained via in-situ polymerization method. Then a series of nanohybrids were successfully prepared with the assistance of scCO2. The obtained nanohybrids were characterized by FTIR, X-ray diffraction, Raman, and their electrochemical performance were further evaluated. It was fascinating to observe that the nanohybrid prepared through one step method with the assistance of scCO2 had superior performance. Such hybrid materials exhibit significant specific capacitance of up to 373 F g-1, which is 1.4 times that of the nanocomposite without the assistance of scCO2 electrode. The experimental results are a proof of concept that scCO2 is an efficient method to help achieve hierarchical multi-component nanohybrids and as well as it may guide the way for designing new functional materials that can be used as electrode materials for lightweight and flexible energy storage device in the near future.