Morphology controlled synthesis of Co(OH)2/TiO2 p-n heterojunction photoelectrodes for efficient photocathodic protection of 304 stainless steel

Flower-like and bulk-like Co(OH)2-modified TiO2 p-n heterojunctions were successfully fabricated by a solvothermal method. Different morphologies resulted in difference in the photoelectrochemical performance; as revealed by the experimental results, flower-like Co(OH)2 microsphere-modified TiO2 showed a narrower bandgap, an upwardly shifted conduction band (CB), and a faster separation and migration of interfacial carriers than bulk-like Co(OH)2. Furthermore, flower-like Co(OH)2 microsphere-modified TiO2 photoelectrode showed a rather low photogenerated potential of −0.53 V in 3.5 wt% NaCl solution, which provided effective photocathodic protection for 304 stainless steel (304SS). The excellent photoelectrochemical performance of flower-like Co(OH)2 microsphere-modified TiO2 photoelectrode results in considerable application prospects of these electrodes as photoanode materials for photocathodic protection.