Fabrication of hierarchical nanohybrids with assistance of supercritical CO_2 for high-performance supercapacitor applications
YANG HongXia;XU Qun;College of Materials Science and Engineering,Zhengzhou University;
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(sc CO2)has been applied in the fabrication of nanomaterials. In view of the soft matter theory and the great tunabililty of sc CO2,it is anticipated that nanocomposites of tailored structure and controlled assembly of nanoparticles can be achieved with the help of sc CO2. 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 sc CO2. 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 sc CO2 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 sc CO2 electrode. The experimental results are a proof of concept that sc CO2 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.