Micron Dimension Highly Oriented PEDOT And PEDOT/α-ZrP Film: Facile Fabrication And Applications

Poly （3,4-ethylenedioxythiophene）（PEDOT） has been recognized asone of the most promising conducting polymers for electrochemicalsupercapacitor. But specific capacitance of PEDOT is limited because of itscompact globular or irregular strings morphology. In fact, the capacity of theelectrochemical supercapacitor is controlled by the structure of the interfacebetween electrode and electrolyte solution. This has been a motivating factor forfabricating porous electrodes with structure elements down to nanometer scale.A single crystal with highly b-axis oriented arrangement poly （3,4-ethylenedioxythiophene）（PEDOT） has been fabricated in a novel unipolarpulse electro-polymerization method （UPEP） from an aqueous solution.Nucleus of PEDOT oligomer grows into rod sprouting branches further. Lots ofpronged rods grow and cross together to form a spongy dendritic networkstructure under the nanoscale. The formation mechanism of PEDOT was basedon the mass change of conducting polymers measured by the electrochemicalquartz crystal microbalance （EQCM）. Structure–properties relationships in PEDOT based supercapacitor were examined. A conformational mechanismduring nucleation and growth process of PEDOT is proposed. The structure,surface morphology and crystallographic ordering of PEDOT films werecharacterized by Fourier transfer infrared spectroscopy （FT-IR）, scanningelectron microscopy（SEM）and X-ray diffraction（XRD）, respectively. Theresults indicate that regular spongy structured PEDOT film prepared by UPEPmethod is consisted of PEDOT branched nano-rods. Electrochemicalperformances of PEDOT films prepared by UPEP and PS were compared usingcyclic voltammetry （CV）, galvanostatic charge/discharge tests andelectrochemical impedance spectroscopy （EIS） in0.3M HClO4,0.1MNaClO4electrolyte. PEDOT film using UPEP method possesses higher specificcapacitances （239.1F g1）, electroactivity and cycling stability than PEDOTfilm prepared by PS method.Organic/inorganic composite has attached more attention owing to itsexcellent electrochemical, electrocatalysisproperties and compatibility. However,many researches showed that the morphology and electrochemical performanceof composites were greatly impacted by preparing conditions. In present work,the influence of different prepared method on physicochemical property ofα-zirconium phosphate is examined. The result indicates that α-zirconiumphosphate prepared in reflux method shows better wettability than hydrothermalmethod. Poly （3,4-ethylenedioxythiophene）/-zirconium phosphate（PEDOT/-ZrP） nanocomposite particles were synthesized on Pt substrate by one-step electrosynthesis using unipolar pulse electro-polymerization method（UPEP） method. The structures of the as-prepared composite particles werecharacterized by X-ray diffraction （XRD）. The optimal mass growth rate onthe Pt substrate is under0.01M EDOT, reflux-ZrP, ton/toff=（0.1s/1.0s）condition, which indicates that PEDOT/-ZrP film is prepared throughwrapping with the organic polymer containing highly b-axis orientedarrangement on the surface of inorganic compound. Combined with CV plot ofPEDOT/-ZrP film in different concentration of Pb2+, Cd2+mixture solution, theelectrochemical behavior and the mechanism of cation exchange wasinvestigated. The result indicates that PEDOT/-ZrP film have strong Pb2+ionselectivity. The wrapping PEDOT on-ZrP processes highly b-axis orientedarrangement with8.04lattice spacing, which is maching with the hydratedradii of Pb2+compared with Cd2+. PEDOT/-ZrP film prepared by UPEPmethod processes excellent selectivity to Pb2+benefitting from suitable latticespacing through molecular-scale design.