Preparation Of Graphene/polyaniline Hollow Spheres By Pickering Template Method And Its Electrochemical Performance

The energy crisis and environmental issues have stimulated people's demand for energy storage equipment.As a new type of energy storage equipment with many unique advantages,supercapacitors have become a hot spot in recent years.Supercapacitors can fill the gaps in the application of batteries and traditional capacitors,thus attracting the attention of scientists.Electrode materials play a decisive role in the performance of supercapacitors.Composite materials usually show better capacitance performance than single materials.Graphene and polyaniline have been widely used as double-layer capacitor materials and pseudocapacitor materials,respectively.Therefore,graphene/polyaniline composite is a strong competitor for supercapacitor electrode materials.Two dimensional sheet material is prone to stacking due to the ?-? interaction between layers,which will reduce the effective contact area between the electrode material and the electrolyte.It is not conducive to the capacitance performance of electrode material.The construction of three-dimensional hollow structure can effectively avoid this problem.Among various preparation strategies of hollow spheres,Pickering emulsion method has unique advantages in the preparation of hollow spheres,such as simple steps,mild conditions,controllability.In this paper,Pickering emulsion is employed to prepare graphene/polyaniline hollow spheres emloying modified graphene as particle emulsifier.Factors affecting electrochemical performance of the hollow microspheres are explored,and their application as electrode materials for supercapacitors is discussed.(1)The preparation of ionic liquid modified graphene/polyaniline hollow spheres and its application in supercapacitorsIonic liquid 1-(3-aminopropyl)-3-methylimidazole bromide(IL-NH2)was used to modify graphene oxide.The prepared ionic liquid-modified reduced graphene oxide(rGO-IL)was used as a particle emulsifier to stabilize the oil phase containing aniline to prepare stable and uniform Pickering emulsion.After initiating the polymerization of aniline,graphene/polyaniline hollow spheres(rGO-IL/PANI HS)was obtained.The wettability of rGO-IL was adjusted by controling modification degree of graphene by IL-NH2.The influence of wettability and concentration of rGO-IL as well as oil-water ratio on the properties of Pickering emulsion was explored.The preparation of rGO-IL and rGO-IL/PANI HS was proved by FT-IR and Raman spectrum,the water contact angle and Zeta potential of rGO-IL were also explored.The Pickering emulsions stabled with rGO-IL were observed by super deep scene 3D microscope and the morphology of rGO-IL/PANI HS was observed by scanning electron microscope.The capacitance performance of rGO-IL/PANI HS was explored by cyclic voltammetry and galvanostatic charge-discharge.The specific capacitance of rGO-IL/PANI HS was able to reach a maximum of 451.8 F/g at a current density of 1 A/g,which was nearly double that of two-dimensional materials.rGO-IL/PANI HS also showed excellent rate performance.The capacitance retention rate of rGO-IL/PANI HS was as high as92.4% when the current density was increased from 0.5 A/g to 10 A/g.(2)The preparation of MnO₂ decorated graphene/polyaniline hollow spheres and its application in supercapacitorsMnO₂ was used to modify graphene oxide.The prepared MnO₂-modified graphene oxide(MnO₂/GO)was used as a particle emulsifier to stabilize the oil phase containing aniline to prepare stable and uniform Pickering emulsion.After initiating the polymerization of polyaniline,the polyaniline@MnO₂/GOaphene ternary hollow sphere(PANI@MnO₂/GO HS)was obtained.The wettability of MnO₂/GO was adjusted by controling the degree of modification of graphene by MnO₂.The influence of wettability and concentration of MnO₂/GO,oil-water ratio and aniline content in oil phase on the properties of Pickering emulsion was explored.The preparation of MnO₂/GO and PANI@MnO₂/GO HS was proved by FT-IR and Raman spectrum.The properties of MnO₂/GO were studied by TGA and Water contact angle measuring instrument.The Pickering emulsions stabled with MnO₂/GO were observed by super deep scene 3D microscope and the morphology of PANI@MnO₂/GO HS was observed by scanning electron microscope.The capacitance performance of PANI@MnO₂/GO HS was explored by cyclic voltammetry and galvanostatic charge-discharge.The specific capacitance of PANI@MnO₂/GO HS was able to reach a maximum of 743.8 F/g at a current density of 1 A/g,which was 2.2 times that of two-dimensional materials.PANI@MnO₂/GO HS also showed excellent rate performance.The capacitance retention rate of PANI@MnO₂/GO HS was as high as 82.5% when the current density was increased from 0.5 A/g to 10 A/g.After 2000 cycles of scanning,PANI@MnO₂/GO HS retained 93% of its initial capacitance,showing good cycle stability.