Electrochemical impedance spectroscopy study of electron transfer at poly(3,4-ethylenedioxythiophene) containing gold nanoparticles coating

Abstract

Electrochemical impedance spectroscopy (EIS) was used for characterization of electron transfer in various redox probes, such as the redox couple ferrocyanide-ferricyanide, ferrocene, ferrocenemethanol, and the poly(3,4-ethylenedioxythiophene) (PEDOT) conducting polymer containing gold nanoparticles. The PEDOT coating was deposited onto platinum (Pt) and glassy carbon (GC) electrodes by galvanostatic electrochemical polymerization from an aqueous solution containing 10^–2 M EDOT and 10^–1 M LiClO₄ as supporting electrolyte. The PEDOT-Au nanoparticles composite coating was prepared by droplet deposition of Au nanoparticles on top of the Pt/PEDOT and GC/PEDOT modified electrodes. The pure PEDOT and PEDOT-Au nanoparticles composite coatings were investigated using EIS and cyclic voltammetry (CV) in 10^–1 M LiClO₄ solution containing various redox probes. The impedance spectra were recorded at the formal redox potential of the redox probes. The charge transfer resistance (R_ct), solution resistance (R_s), exchange current density (i₀), standard rate constant (k₀), and double-layer capacitance (C_dl) were calculated from the EIS data.