Preparation,Modification And Photo-generated Cathoodic Protection Performance Of Ti Based TiO₂ Nanotube Arrays

Photogenerated cathodic protection is an environmentally friendly metal anticorrosion technology.TiO2 is a candidate for photoanode due to its high conduction band energy level and chemical stability.However,the application of is restricted by low quantum yield and unsustainability in dark state.In this paper,we use organic and inorganic semiconductor with narrow band gap sensitized Ti based TiO2 nanotube arrays to construct multiple-orderly heterostructures,thus improving photo-generated cathodic protection performance;Establishing the relationship between electric field and charge transfer in a photo-generated cathodic protection system by constructing different metal-semiconductor heterojunctions,which will provides a theoretical basis for the development of photo-generated cathodic protection technology and the selection of semiconductors.The main research contents and results are as follows:(1)P-type organic semiconductor polythiophene(Pth)sensitized TNAs composites were synthesized through a electrochemical two-step anodic oxidation and anodic polymerization methods.The morphology,optical property and photoelectrochemical performance of Pth/TNAs samples with different polymerization time were investigated.Pth with appropriate deposition amount increases light absorption as well as the inner electric field that drives electrons transfer from semiconductor to the connected metal.This enhances the photoelectrochemical performance of Pth/TNAs composites,thus improving photo-generated cathodic protection of 304 stainless steel with irradiation.Meanwhile,electrons reflux from metal corrosion will be retarded for the unidirectional continuity of electrons in p-n heterojunction and Schottky heterojunction without irradiation,which shows application potential for photo-generated cathodic protection in dark.(2)In2S3 quantum dots were deposited onto the TiO2 nanotube array surface by facile ultrasonic assisted continuous ion layer adsorption and reaction method.Suitable deposition amount of In2S3 was investigated by controlling the deposition times.The In2S3/TNAs sample with two deposited cycles possesses the optimal photoelectrochemical and photo-generated cathodic protection performance,which mainly benefit from the In2S3 with narrow band gap broadening the optical absorption range,the n-n heterojunctions at the interface between In2S3 and TiO2 improves the photo-generated electron-hole pairs separation efficiency.High quantum yield increases the potential difference in metal-semiconductor heterojunction,thus improving the photo-generated cathodic protection performance for coupled 304 stainless steel.(3)TiO2??-Fe2O3 and NiO nanoparticles electrode electrically connected to metal to investigated the effect of inner electric field in metal-semiconductor heterojunction on metal corrosion.Photo-generated cathodic protection and photo-induced corrosion performance of semiconductor for metals were analyzed by photoelectrochemical and corrosion morphology.N-type semiconductor TiO2 and p-type semiconductor NiO provide photo-generated cathodic protection for coupled 304 stainless steel and Q235 carbon steel.While ?-Fe2O3 will cause corrosion acceleration of Q235 carbon steel and inhibit the corrosion of 304 stainless steel under illumination.Photo-generated cathodic protection and photo-induced corrosion are determined by flat band potential of the semiconductor and corrosion potential of metal,which induced the information of the inner electric field to drive charge transfer.