Two types of overoxidized poly (3, 4-ethylenedioxythiophene) films on Au microelectrode: Electrochemical preparation and characterization

Poly (3, 4-ethylenedioxythiophene) (PEDOT) films were prepared by electro-oxidation in an aqueous solution on Au microelectrode. Electrolyte solutions and polymerization parameters were optimized previously for further overoxidation. The effect of overoxidation time has been optimized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), which signifies that overoxidation film with 45s at 1.35V presents strong adsorption as well as good conductivity. The other one-step overoxidation film by direct CV ranging from −0.6V to 1.35V was polymerized for comparison. Scanning electron microscope (SEM) and fourier transform infrared (FTIR) spectroscopy were used for monitoring the functional groups evolution and morphological changes. Both of them presents increased abundant oxygen functional groups and roughness, yet exhibit dendritic morphology and piles of spherical protrusions respectively. Moreover, double-step overoxidized film show better electrochemical performance toward lead ion sensing. These characterizations may bring out the appearance of novel properties that may be beneficial for specific sensing applications.