关键词: 石墨烯复合材料, 聚苯胺, Pickering乳化剂, 空心微球, 电化学性能

In recent years, hybrid nanomaterials of graphene and polyaniline have attracted extensive interest and have been considered as promising electrode materials for supercapacitor combining the advantages of both materials with synergistic effects. In contrast to the well-developed two-dimensional planar structure of graphene-PANI, the pursuit of hollow gra-phene-PANI hybrid structure is relatively less investigated. The hollow micro/nanostructured graphene-PANI materials with the nanoscale shell, inner cavity and pore structures, is highly expected to exhibit remarkable enhanced supercapacitor performance owing to the enhanced specific surface area and shortened diffusion length for both charge and mass transport. In this work, a novel kind of graphene-polyaniline hollow capsules (PANI-SGR HS) was prepared via Pickering emulsion polymerization using sulfonated graphene (SGR) as Pickering stabilizer. Amphiphilic sulfonated graphene is prepared by a covalent modification and used to stabilize oil phase containing aniline monomer. Aniline molecules were adsorbed to the oil-water interface owing to the electrostatic interaction between amino groups of aniline and sulfonic groups of SGR, which subsequently underwent interfacial polymerization at the oil/water interface upon the addition of initiator ammonium persulfate (APS). The effects of the sulfonation degree of graphene, the SGR concentration as well as the oil/water volume ratio on the stability and morphology of SGR stabilized emulsions were investigated in detail. The SGR with appropriate sulfonation degree can produce stable emulsions. The average diameter of the emulsion droplet decreased with the increasing concentration of SGR stabilizer. The emulsion stability can be improved with the increased water phase infraction. After polymerization of aniline and removal of the oil phase, three-dimensional hollow graphene-polyaniline sphere (PANI-SGR HS) was obtained. The morphology of PANI-SGR HS was observed by scanning electron microscopy (SEM). The special hollow sphere structure not only enlarged the liquid contact area but also improved charge carrier mobility. The hollow sphere modified electrode exhibited excellent performance with a specific capacitance of 480.59 F·g^-1 at 1 A·g^-1, which is much higher than 251 F·g^-1 of the common two-dimensional stacked graphene-polyaniline film. This novel three-dimensional PANI-SGR HS material may have potential applications in energy storage.

Key words: graphene composite, polyaniline, Pickering stabilizer, hollow sphere, electrochemistry