Photoelectrochemical cathodic protection of Cu2O/TiO2 p-n heterojunction under visible light

The Cu 2 O/TiO 2 p-n heterojunction composite photoelectrodes were prepared by depositing Cu 2 O nanoparticles on the surface of TiO 2 nanotubes via anodic oxidation and constant current deposition. Field emission scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) analyses showed that Cu 2 O nanoparticles not only deposited on the surface of TiO 2 nanotube array, but also on the wall of TiO 2 nanotubes. The Cu 2 O deposition amount could be adjusted by changing the deposition time. The photoelectrochemical cathodic protection (PECCP) performance of the prepared photoelectrodes for 316L stainless steel (SS) was tested under visible light. The constant current deposition time had a significant effect on the PECCP performance of Cu 2 O/TiO 2 -X photoelectrodes and Cu 2 O/TiO 2 -20 had the best PECCP performance for the coupled 316L SS. This was attributed to the appropriate amount and thickness of Cu 2 O to form p-n heterojunctions with TiO 2 , in which separation of the photogenerated carriers was accelerated and transfer of the photogenerated electrons to 316L SS for PECCP was facilitated.