Studies On Controllable Synthesis Of Two Dimensional Conducting Polymers By Salt-templated Method And Their Properties

Owing to its environmental friendliness,biocompatibility,and high electrical conductivity,conducting polymers with unique one-dimensional delocalized conjugated structures have been widely applied in energy related application including solar cell,photocatalysis and supercapacitors.In most cases,the performance of these energy conversion and storage devices is determined by the electrical and optical properties of conducting polymers.Meanwhile,these properties can be tailored by adjusting the molecular structure of the polymers and the dimensionality of their nanostructure.Two-dimensional（2D）morphology are promising for the realization of fascinating physical and chemical properties when the molecular is confined to a plane.Furthermore,the ultrathin feature of2D morphology usually owns the high specific surface area and lead a fast-ionic diffusion which are well-suited for energy related applications.However,it is difficult to synthesis conducting polymer nanosheets due to the strong intermolecular bonds between different molecular chains that give rise to the molecular chain crosslinking and the formation of bulk structure.Thus a simple and efficient method for fabricating 2D conductive polymer is urgently needed.Herein,we focus on the controllable preparation of 2D conducting polymers and optimize its electrochemical performance for supercapacitors.The main contents for this thesis are as following:（1）The 2D conducting polymers（PPy,PANi,PEDOT）were successfully fabricated by using salt（Cu Cl₂·2H₂O）template method.The Cu Cl₂·2H₂O salt was used as template and oxidant in the vapor phase polymerization.The size and thickness of conducting polymers nanosheets could be controlled by the size of Cu Cl₂·2H₂O template and reaction time.Furthermore,a highly conductive,flexible and large-area PPy film with a high transparency was prepared on the surface of large Cu Cl₂·2H₂O crystal.We believe that other 2D conducting polymers could be synthesized by using a suitable oxidant in this system as well.（2）The growth mechanism of the conducting polymer nanosheet was discussed.The confinement effect of the gas-solid interface played a critical role in the bottom-up growth of the 2D conducting polymers.We assumed that the partial reduction of Cu Cl₂·2H₂O could release some freedom H₂O molecules and form the Cu Cl₂ liquid layer and diffuse to the top surface of the polymer,continuing the growth of the PPy nanosheets.Thus the thickness could be controlled by the reaction time.（3）The electrochemical performance of PPy nanosheet was studied as electrode material for supercapacitor.The free-standing PPy"gel"electrode was prepared by filtration and soaking,which was used to assemble symmetric supercapacitor using 1M H₂SO₄ as electrolyte.This free-standing electrode exhibited a high specific capacitance of 355 F/g and volumetric capacitance of 320 F/cm³.When the scan rate was increased to 5000 m V/s,the specific capacitance of this electrode still reached up to 196 F/g.Furthermore,the power density of the symmetric device was extremely high,suggesting the advantages of two-dimensional conducting polymers for energy storage application.