TiO2 is an attractive semiconductor suitable for photocathodic protection, but its weak absorption of visible light and low quantum yield limit its usage. Here, a new heterostructured SnIn4S8 nanosheet/TiO2 nanotube photoanode was prepared and its photocathodic protection performance was analyzed. SnIn4S8 nanosheets were uniformly deposited on the surface of the TiO2 nanotube via a solvothermal treatment. The SnIn4S8/TiO2 composite exhibited better photocathodic protection performance compared with pure TiO2 nanotubes, owing to its good visible-light response and photogenerated carrier separation efficiency. Moreover, the composite exhibited a maximum photocurrent density of 100 μA cm-2 for a 6 h solvothermal reaction under visible light irradiation. The negative shift of the photoinduced potential of Q235 carbon steel connected to the composite could reach 0.45 V versus SCE. Therefore, the SnIn4S8/TiO2 composite can offer efficient photocathodic protection for Q235 carbon steel against corrosion in 3.5 wt% NaCl solution. This work provides a new approach for the development of high-efficient photoanode materials for the photocathodic protection of metals.
Keywords: Carbon steel; Photocathodic protection; SnIn4S8; TiO2 nanotubes.