Fabrication Of TiO₂ Composite Films With Energy Storage Ability And Their Photocathodic Protection Effects On 403 Stainless Steel

A TiO2 material may be used as a non-sacrificial anode and provide a photocathodic protection effect on a metal under illumiatnion without an extra power supply,which is great importance for corrosion control of metals.Improving the visible light absorption and enhancing the photoelectric conversion efficiency of TiO2 materials are the key issues for the practical application and the future development of the photoelectrochemical anticorrosion.In addition,it is very important to develop the Ti02 materials with energy storage ability which could maintain the cathodic protection after the illumination is cut off.Therefore,in this work,the modifications of TiO2 films were carried out by coupling other semiconductors with the films.And the photoelectrochemical and photochcthodic protection properties of the modified TiO2 composite films with different heterostructures or a cascade type energy band structure were studied.The main progresses are listed as follows:(1)A WO3/TiO2 nanotube composite film was successfully fabricated by the anodization process and the electrodeposition method.When the composite film was used as a photoanode and coupled to 403 stainless steel(403SS)in a 0.5 mol/L NaCl solution,the potential of 403SS was about 370 mV lower than its corrosion potential under white light illumination.The composite film could provide an effective photocathodic protection effect for the 403SS.Because of the reductive energy storage ability of WO3,the composite film could provide cathodic protection after the light illumination was turned off.(2)A WO3/SrTiO3/TiO2 composite film with a cascade band structure was fabricated from the TiO2 nanotube array film by the hydrothermal reaction and electrodeposition.The separation efficiency of photogenerated electron-hole pairs was higher and the composite film presented a better photoelectrochemical property as compared to the pure TiO2 nanotube film.The potential of 403SS in a 0.5 mol/LNaCl solution was shifted negatively and the interface charge transfer resistance decreased when it was coupled to the composite film,which had a photocathodic protection effect and an energy storage ability.(3)A hydrothermal method followed by calcination treatment was used to prepare a p-n heterojunction NiO/TiO2 composite film from a TiO2 nanotube array film.The results showed that the composite film prepared by 1 h hydrothermal reaction and annealing at 500 ? exhibited strong visible light absorption and an excellent photoelectric conversion efficiency.The photocathodic protection of 403 SS in a 0.5 mol/L NaCl solution by the composite film was better than that by the pure TiO2 nanotube film.The composite film could provide continuous cathodic protection for the 403SS for 15.5 h after 2.5 h illumination,resulting from the oxidative energy storage ability of NiO in the film.