Enhanced photocathodic protection performance of Ag/graphene/TiO composite for 304SS under visible light.

Ag and graphene co-sensitized TiO composites were successfully fabricated and used as photoanodes for photogenerated cathodic protection of 304 stainless steel (304SS) under visible light. Graphene films was firstly deposited onto the TiO nanotube (NT) films via cyclic voltammetric electrodeposition. Ag/graphene/TiO films were then fabricated via dipping and photoreduction method. The morphology, composition and optical response of the Ag/graphene/TiO NT composites were characterized by scanning electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, UV-vis diffusion reflectance spectroscopy, respectively. The photocathodic protection performance of the Ag/graphene/TiO composites were systematically studied through open-circuit potential and potentiodynamic polarization measurements in 3.5 wt% NaCl solution under visible light (λ > 400 nm). The composites exhibited enhanced photogenerated cathodic protection performance for 304SS under visible light irradiation compared to pure TiO. Graphene and Ag have a synergistic effect on the enhancement of photocathodic protection performance of TiO. The composites prepared with 30-cycle graphene film and 15 mM AgNO solution showed the optimal corrosion protection performance.