Polypyrrole nanowire/TiO2 nanotube nanocomposites as photoanodes for photocathodic protection of Ti substrate and 304 stainless steel under visible light

A new photoanode polypyrrole nanowire/TiO2 nanotube (PPy NW/TiO2 NT) nanocomposite material with a coaxial heterojunction structure is constructed by electrodeposting p-type polypyrrole nanowire into n-type TiO2 nanotubes. Photo-induced open circuit potential, photocurrent density, electrochemical impedance spectroscopy, and Tafel curves are measured under visible light to evaluate the photocathodic protection effect and anticorrosion properties of the nanocomposite. The results indicate that the synergistic effect between the photogenerated cathodic protection and the favorable corrosion resistance of the nanocomposite makes PPy NW/TiO2 NTs nanocomposite a promising material for protecting Ti substrate and the coupled 304 stainless steel from corrosion. (C) 2015 Elsevier Ltd. All rights reserved.