Preparation And Electrochemical Performance Of Hollow Conducting Polymer Nanosphere@ Nitrogen-Doped Graphene Composites

In this paper, hollow polypyrrole (PPy) microspheres and hollow polyaniline (PANI)spheres had been prepared by a new copolymer as templates, then hollow PPy nanospheres and nitrogen-doped graphene (NG/H-PPy) composites were synthesized by electrostatic interaction. The nanobeads have been characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD),X-ray photoelectron spectroscopy (XPS),Raman spectra and Fourier transform infrared spectra (FTIR). What's more, different electrochemical methods including cyclic voltammetry (CV),galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) have been applied to study the electrochemical properties.The main research of this paper is as follows:1. Uniform poly (methyl methacrylate-butyl methacrylate-methacrylic acid) (PMMA-PBMA-PMAA) latex microspheres as sacrificial templates were synthesized by using an emulsion polymerization method. Using this copolymer as template and hydrochloric acid as dopant, the hollow microspheres were prepared by in situ polymerization. The shell thickness of hollow PPy microspheres were controlled by the amount of pyrrole monomer, and then investigated the electrochemical properties of different shell thickness. With the increase of the amount of pyrrole monomer, the specific capacitance of the hollow microspheres increases gradually, and then tends to be stable. The specific capacitance reaches 506 F g-1 while the volume of pyrrole is 2.0 ml.2. Uniform poly (methyl methacrylate-butyl methacrylate-methacrylic acid) (PMMA-PBMA-PMAA) latex microspheres as sacrificial templates were synthesized by using an emulsion polymerization method. Using this copolymer as template and hydrochloric acid as dopant, the hollow PANI microspheres were prepared by in situ polymerization. The specific capacitance of H-PANI is as high as 583 F g-1 at a current density of 1 A g-1 and enhanced stability about 69 % after 500 cycles at a current density of 5 A g-1, indicating that H-PANI has an impressive capacitance and excellent cycling performance.3. NG/H-PPy composites were synthesized by electrostatic interaction. In this process,NG sheets provided huge areas for H-PPy to attach on effectively and due to the large specific surface area of the NG and H-PPy, the electrochemical performance of the composite is excellent. The specific capacitance of NG/H-PPy composites based on the three-electrode system is as high as 575 F g-1 at a current density of 1 A g-1 and enhanced stability about 90.1 % after 500 cycles, indicating that the composite has an impressive capacitance and excellent cycling performance.