Role of supporting electrolyte on the corrosion performance of poly(carbazole) films deposited on stainless steel

•Poly(carbazole) deposited on 304-SS in presence of three different perchlorate salts.•Tetrabutylammonium, sodium and lithium perchlorate salts were used in the study.•Effect of counter cation of the dopant on protection performance was explored.•Poly(carbazole) produced from tetrabutylammonium salt exhibited the best corrosion performance. This work presents a comparative study of supporting electrolyte effect on the protection ability of poly(carbazole) films deposited on 304 stainless steel. Tetrabutylammonium, sodium and lithium perchlorate salts were used as supporting electrolyte in the investigation. Poly(carbazole) films were synthesized by electropolymerization of carbazole using cyclic voltammetry from acetonitrile medium containing monomer and supporting electrolyte. Protective properties of poly(carbazole)s were investigated in 1M H2SO4 solution using Eocp–t curves, Tafel polarization and electrochemical impedance spectroscopy. Corrosion test results revealed that supporting electrolyte affects conductivity of deposited films. Poly(carbazole) synthesized from tetrabutylammonium perchlorate exhibited better protection performance than the other poly(carbazole)s.