Preparation and photocathodic protection property of ZnIn 2 S 4 /RGO/TiO 2 composites for Q235 carbon steel under visible light.

For improving the photocathodic protection performance of TiO2 photoanode, ZnIn2 S4 /reduced graphene oxide (RGO)/TiO2 nanotubes (NTs) composite was synthesized by electrochemical anodizing combined with hydrothermal method. The photoelectrochemical and photocathodic protection properties of the ZnIn2 S4 /RGO/TiO2 composite were investigated in detail. Compared with pure TiO2 NTs, the ZnIn2 S4 /RGO/TiO2 composite showed a significant improvement in photocathodic protection performances. The photogenerated open circuit potential drop of ZnIn2 S4 /RGO/TiO2 coupled with Q235 carbon steel in 3.5 wt% NaCl solution under visible light could reach 420 mV versus saturated calomel electrode, which was more than twice as much as that of pure TiO2 . The photogenerated current density of ZnIn2 S4 /RGO/TiO2 could reach 5.6 mA cm-2 , which was twice as much as that of pure TiO2 . The appearance of the adsorbed oxygen (OA ) enabled the ZnIn2 S4 /RGO/TiO2 to have better photo-carrier separation efficiency and better photogenerated cathodic protection than pure TiO2 . The present work demonstrated ZnIn2 S4 /RGO/TiO2 could be a potential material for photoanodes because of its better visible-light response, higher electrical conductivity and smaller charge transfer resistance.