Photocathodic Protection of 304 Stainless Steel by Bi2S3/TiO2 Nanotube Films Under Visible Light

Abstract

We report the preparation of TiO₂ nanotubes coupled with a narrow bandgap semiconductor, i.e., Bi₂S₃, to improve the photocathodic protection property of TiO₂ for metals under visible light. Bi₂S₃/TiO₂ nanotube films were successfully synthesized using the successive ionic layer adsorption and reaction (SILAR) method. The morphology and structure of the composite films were studied by scanning electron microscopy and X-ray diffraction, respectively. UV-visible diffuse reflectance spectra were recorded to analyze the optical absorption property of the composite films. In addition, the influence of Bi₂S₃ deposition cycles on the photoelectrochemical and photocathodic protection properties of the composite films was also studied. Results revealed that the heterostructure comprised crystalline anatase TiO₂ and orthorhombic Bi₂S₃ and exhibited a high visible light response. The photocurrent density of Bi₂S₃/TiO₂ was significantly higher than that of pure TiO₂ under visible light. The sensitization of Bi₂S₃ enhanced the separation efficiency of the photogenerated charges and photocathodic protection properties of TiO₂. The Bi₂S₃/TiO₂ nanotubes prepared by SILAR deposition with 20 cycles exhibited the optimal photogenerated cathodic protection performance on the 304 stainless steel under visible light.