Electropolymerization and corrosion protection performance of the Nb:TiO2 nanofibers/polyaniline composite coating

A Nb:TiO2 nanofibers/PANI electrically conductive composite coating is electropolymerized on 316 stainless steel for bipolar plates of a proton-exchange membrane fuel cell. The corrosion behavior of the composite coating in the simulated cathodic and anodic environments (0.3 M HCl bubbled with air or H-2 at 25 degrees C) is investigated by the potentiodynamic polarization, potentiostatic polarization, open circuit potential and electrochemical impedance measurements. The experimental results indicate that the corrosion current density of the composite coating coated 316 stainless steel decreases to about 2.75 and 6.31 mu A cm(-2) in the simulated cathodic and anodic environments, respectively. The corrosion potential increases by more than 400 mV vs. SCE. During the 180 h immersion, the composite coating shows high chemical stability and provides effective protection for the 316 stainless steel through its physical barrier effect and in-situ anodic protection effect. (C) 2019 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.