A Study On The Electrochemical Degradation Of Polyaniline

Among the virious kinds of conducting polymers, polyaniline(PANI) has importantapplication prospect in chemical power supply, electronic devices, special coatings due tothe advantages of its ease of synthesis, good electrical conductivity. However,electrochemical stability is the key whether the conducting polymer can be applied in thefield of electronics.In this paper, PANI film on Pt electrode was prepared as working electrode, and theelectrochemical degradation behavior was studied by cyclic voltammetry(CV) andelectrochemical impedance spectrum measurements (EIS). The relative peak current Iprel=Ip(B1+B2)/IpA（B1and B2represent the oxidation peak of degradation products, Arepresents the oxidation peak of the leucoemeraldine to emeraldine）was used to describethe degradation kinetics of PANI-H2SO4（PANI doping with H2SO4）film. The resultsshowed that the overall degradation was limited by first-order reaction kinetics. The effectof pH，electrochemical polarization and counter anion was also studied: the electrochemicalactivity didn’t change when the PANI film was submerged in different concentration of H+,but the concentration of H+in the electrolyte affected the electrochemical activity andstability, the higher concentration of H+, the higher the doping level of PANI is, and it ismore vulnerable for PANI to suffer the attact of the nuclephilic particles; the degradationproducts in the electrolyte increased with the increasing polarization potential; the molarconcentration of the degradation products of PANI doping with different counter anion wasin step with the cyclic voltammogram relative peak current and the size of the particle sizeof the PANI, it is PANI-H2SO4> PANI-HNO3>PANI-HCl>PANI-HClO4.The PANI doping with copper ion was synthesised using cyclic voltammetry,theconductivity of the PANI film was improved after doping with copper ion, but it isvulnerable to be damaged by an electrochemical polarization owing to the interactionbetween the copper ion and the chain of PANI was very weak. The presence of Cu2+inelectrolyte significantly impoved the conductivity and capacitance of PANI film, while thepresence of Cu2+in a copper ionic concentration corrosion cell accelerated the electrochemical degradation of PANI film.