Electrochemical property of organosulfide-conducting polymer composite electrode

Abstract

DMcT (2,5-dimercapto-1,3,4-thiadiazole)/ polyaniline (PAn) composite electrode is prepared by DMcT electrochemical oxidation on PAn film electrode in the DMcT solution with a different pH. The electroactivity, DMcT concentration profile in the PAn film and the in-situ resistivity of the composite are investigated in the electrolyte solution with DMcT or without DMcT. The composite film prepared in acidic condition shows the higher current density and the better electroactivity than those prepared in neutral and basic conditions because the protons may contribute to the protonation of PAn film. When DMcT/PAn composite is transferred into the solution without DMcT, it has the enhanced electroactivity such as the anodic peak shift to a lower potential and the increased cathodic current. The enhancement of electroactivity is considered to be caused by the increase of ion diffusivity coefficient and the decrease of electrical resistivity. The ion diffusivity increases due to the detachment of excess DMcT from the film and the resistivity decreases by the dissociation of DMcT from the imine group of PAn. Annealing effect on the electroactivity of polyaniline (PAn) complexed with various acids has been investigated. The polyaniline - p-toluene sulfonic acid complex (PAn-pTSA) and polyaniline - hydrochloric acid complex (PAn-HCl) show the decreased electroactivities with annealing temperature, but the polyaniline - dodecylbenzene sulfonic acid complex (PAn-DBSA) shows an increase in electroactivity upto 150℃ annealing process and then a decrease at 180℃ annealing process. The increase of the electroactivity for PAn-DBSA can be explained by an additional thermal doping of undoped DBSA with annealing. The electrical conductivities at a high temperature of 230℃ are in the order of PAn-pTSA > PAn-DBSA > PAn-HCl. The PAn-pTSA shows the highest conductivity because pTSA shows the most thermal stability. The decreased conductivity at a high temperature may be due to the dedop...