Fabrication of multi-layered TiO2/CdS@ZnS nanocomposite film for highly stable and efficient photocathodic protection of carbon steel

To effectively protect carbon steel in marine environments, TiO2 nanobelts were synthesized on the surface of the Ti sheet via electrochemical anodization, and CdS@ZnS semiconductors were deposited on the TiO2 surface using the SILAR method. The results showed that under light irradiation, the OCP of the TiO2/CdS@ZnS4 nanocomposite film coupled with carbon steel reached the most negative value of-1.05 V (vs. SCE), with a corresponding photocurrent density of 0.939 mA/cm2, approximately three times higher than that of pure TiO2. This enhancement is attributed to the multi-layered structure formed by the differing Fermi levels of various semiconductors, which facilitates the effective separation of photogenerated electrons and holes. Consequently, the multi-layered composite system exhibits highly stable and efficient photocathodic protection performance for carbon steel.