Zn3In2S6/TiO2 Nanocomposites for Highly Efficient Photocathodic Protection to Carbon Steel

Photocathodic protection has evoked great attention in stainless steel protection; however, it has not been fully studied on carbon steel. This study has prepared a series of TiO2/Zn3In2S6 nanocomposite films by combining anodic oxidation with hydrothermal methods, in which composition and morphology together with optical properties have been characterized. This heterojunction TiO2/Zn3In2S6 has allowed access to visible-light absorbance. Photoelectrochemical tests suggest that this film can supply effective photocathodic protection to carbon steel. The maximum photogenerated potential drop achieved on TiO2/Zn3In2S6-30 coupled to carbon steel is about −0.49 V even after 80 h of illumination, and the corresponding photocurrent is 1.91 mA·cm–2, which is about 5 times higher than that of pure TiO2. This is benefited from the effective photogenerated charge separation by the built-in electric field in the heterojunction. The detailed mechanism has been discussed in the paper.