Dual-function photoelectrode of TiO2 nanotube array/CdZnS/ZnS heterojunction for efficient photoelectrochemical cathodic protection and anti-biofouling

The low photoelectric conversion efficiency of photoelectrode is an important factor that limits the application in photoelectrochemical cathodic protection (PECCP) field for marine anti-corrosion of metallic structures. In this work, a photoelectrode of TiO2/CdZnS/ZnS triple-phase heterojunction was fabricated by loading the narrow-band CdZnS associated with the broad-band ZnS via hydrothermal and continuous ion layer adsorption methods, respectively. The composite of CdZnS enhances the photoelectric conversion ability of TiO2, while the ZnS composite can prevent the CdZnS from photo-corrosion and suppress the spillover of the photogenerated electrons. The three-phase heterostructure effectively improves the PECCP performance on 316L stainless steel (SS) under simulated solar irradiation, especially in 3.5 wt% NaCl solution without the sacrificial agent. In addition, the prepared TiO2/CdZnS/ZnS photoelectrode also performs anti-biofouling effect evidenced by the high removal efficiency of Pseudomonas aeruginosa (P. aeruginosa), which can be attributed to the oxidizability of photogenerated holes. The TiO2/CdZnS/ZnS triple-phase heterojunction with desirable performance is a promising semiconductor material for the applications of PECCP and anti-biofouling.