Fabrication of TiO₂/CdS/Co(OH)₂ composite and its application in photoelectrochemical cathodic protection of 304 stainless steel under visible light

CdS quantum dots (QDs) and Co(OH)2 were deposited on the surface of TiO2 nanotube arrays (NTAs) by successive ionic layer adsorption and reaction (SILAR), and the performance of the composite in photoelectrochemical (PEC) cathodic protection was studied. Due to the narrow band gap of CdS QDs and the formation of type II heterojunction with TiO2, the TiO2/CdS (Ti/Cd) composite exhibited enhanced PEC properties in 3.5 wt% NaCl solution. After deposition of Co(OH)2, the valence conversion of Co(II) and Co(III) improves the separation efficiency of charge carriers, the cathodic protection performance of TiO2/CdS/Co(OH)2 (Ti/Cd/Co) composite is further improved.