Studies On Synthesis And Properties Of Poly (3,4-ethylenedioxythiophene)/Gra-Phene?Carbon Nanotube Composites

With the rapid development of technology, conducting polymer and their composites have been paid widely attention since its exhibit super property. Among the variety of conducting polymers, poly(3,4-ethylenedioxythiophene) widely applied in solar cell, supercapacitor and sensor because its good environmental stability, high conductivity and electrooptic activity. Meanwhile single-walled carbon nanotubes(CNT) and graphene oxide(GO) also widely used in supercapacitor with their ultrahigh mechanical strength, superior electrical and thermal conductivity. The conducting polymer/carbon material composites can exhibit porperty includ organic and inorganic characters, and also emerge new properties with their synergetic effect or complementary behaviors, which greatly opened up composites applications.In this paper, the functionalized carbon materials were synthesized by Suzuki coupling reaction, and the thiophene type units were grafted on carbon material surface. Subsequently, the functionalized carbon materials were covalently linked with PEDOT chains via thiophene type units. Structure and surface morphology of the composites were characterized by using Fourier transform infrared spectroscopy(FTIR), ultraviolet–visible(UV–vis), Raman spectroscopy absorption spectroscopy, Xray diffraction(XRD), scanning electron microscopy(SEM), energy-dispersive X-ray spectroscopy(EDS) and thermogravimetric analysis(TGA) studies. The electrochemical and photocatalytic performances of composites were investigated by galvanostatic charge/discharge measurement(GCD), cyclic voltammetry(CV), electrochemical impedance spectroscopy(EIS), cycle lifetimes and photocatalytic degradation. The details are summarized as follows:(1) Grafting different thiophene units on single-walled carbon nanotubes, and then incorporated into PEDOT, respectively. The different proportion of 2-ThCNT/PEDOT, 3-Th-CNT/PEDOT, EDOT-CNT/PEDOT composites were synthesized by situ polymerization. We discussed the influence of carbon nanotubes for electrochemical properties of composites, which based on its different content and modification units. Comparative result showed that 10wt% 3-Th-CNT composite had the highest electrochemical activity with a specific capacitance value of 190 F/g than others.(2) By modified graphene oxide on its surface and introduction of 3-thienyl unit(Th-GO), and then Th-GO covalently linked with PEDOT chains via in situ polymerization of 3,4-ethylenedioxythiophene(EDOT) monomer to yield Th-GO /PEDOT, the structure and electrochemical properties of PEDOT/Th-GO composite with the loading of different weight percentage of thiophene-grafted GO ranging from 40 to 70 % in reaction medium were studied. Comparative result showed that the composite prepared from 50 wt% with the high doping level and good conjugation among all composites. Electrochemical analysis suggested that the highest specific capacitance of 320 F/g at a current density of 1 A/g with good cycling stability(capacitance retention of 80 % at 1 A/g after 1000 cycles) was achieved for the composite prepared from 50 wt% Th-GO content in reaction medium.(3) By synthesizing GO/PEDOT and Th-GO/PEDOT composites, compared the effects on the electrochemical and photocatalytic properties of the composites. And synthesizing Th-GO/PEDOT(without CTAB) composite shows that the effect of CTAB on the electrochemical and photocatalytic properties of the composite. The results indicate that the conjugation degree, doping level and thermal stability of composite were improved through introducing thiophene unit on GO surface and adding CTAB in the reaction system,and further improve the electrochemical performance. However, the thiophene units on GO surface hinder the reception and transmission electron, and then reducing the composite's photocatalysis. While the CTAB can greatly improve the photocatalytic performance of the composite.(4) The PEDOT, Th-GO/PEDOT and GO/PEDOT composites were successfully synthized by solid-state heating method. The characterization results indicate that modified GO has good dispersion and corresponding composite exhibited excellent electrochemical properties. However, the photocatalytic performance testing results indicate that GO/PEDOT has the best photocatalytic performance.