Enhanced photoelectrochemical performances of ZnS-Bi2S3/TiO2/WO3 composite film for photocathodic protection

A novel platelike ZnS-Bi2S3/TiO2/WO3 composite film was constructed on a fluorine-doped tin oxide substrate through hydrothermal treatment combined with thermal hydrolysis and successive ion layer absorption and reaction. The composite film showed enhanced photoelectrochemical performances compared with a pure WO3 film. The ZnS-Bi2S3/TiO2/WO3 film under white light illumination could negatively shift the potential of the coupled 403 stainless steel in a 0.5 M NaCl solution by 540 mV relative to its corrosion potential, showing effective photocathodic protection. After the light was stopped, the composite film continuously provided the cathodic protection for 18 h owing to its charge storage ability.