Fabrication of heterostructured β-Bi2O3-TiO2 nanotube array composite film for photoelectrochemical cathodic protection applications

Highlights: • A β-Bi₂O₃ sensitized TiO₂ nanotube film was fabricated. • The β-Bi₂O₃-TiO₂ composite film exhibited a broader light absorption region. • The enhanced photoelectrochemical properties were obtained for the β-Bi₂O₃-TiO₂ film. • The composite film provided effective photocathodic protection for stainless steel. - Abstract: An ordered TiO₂ nanotube array (NTA) film was first fabricated on a Ti substrate by anodization, β-Bi₂O₃ nanoparticles were then electrodeposited on the film for obtaining a heterostructured β-Bi₂O₃-TiO₂ NTA composite film with enhanced photocathodic protection performances. Compared to the bare TiO₂ NTA film, the composite film showed a wider light absorption region and higher charge carrier separation efficiency. Under white light illumination, the composite film as a photoanode made the potential of 403 stainless steel in a 0.5 M NaCl solution decrease by 450 mV relative to its corrosion potential, showing an effective photoelectrochemical cathodic protection effect.