| As the functional material develop rapidly. Nano-structured semiconductors are of vital importance on the development of functional material.The photoelective performance are essential properties for this king of materials. The investigation of titanium dioxide for photogenerated cathode protection of metals has received great attention. In addition, if illuminated titanium dioxide is in contact with metal, electrons are injected from the semiconductor to the metal via the conduction band. As a result, the potential of the metal will be shifted in the negative direction to the flatland potential of titanium dioxide. If the potential is more negative than the potential at which the metal beings to oxidize, the metal can be protected from corrosion. So titanium dioxide can realize corrosion protection of the marine material as non-sacrificial protective material. The photocathodic protection performance of titanium dioxide is dependent on the photoelectrochemical efficiency, which select the appropriate doped in order to obtain high photoelectric conversion efficiency and visible-light response of the electrode material is of the greatest concern.In this dissertation, Ti (OC4H9)4 was used as precursor, C4H11NO2 was used as inhibitors to prepared nano-titanium dioxide film on the stainless steel substrate by neutral sol-gel method. In the preparation process, Modified titanium dioxide thin films were prepared by adding PEG; respectively, iron-doped titanium dioxide thin films were prepared with ferric nitrate as iron source, nitrogen-doped titanium dioxide thin films were prepared with urea as nitrogen source. Modified and doped titanium dioxide thin films were prepared to look forward to enhance photoelectric conversion efficiency and to broaden the scope of photoelectric response. This paper used laser particle size analysis and Zeta potential to test the modification on the properties of titanium dioxide sol; the crystal structure, properties and surface morphology of modified titanium dioxide were characterized using X-ray diffraction (XRD), thermal analysis (DTA-TG), infrared absorption (IR), and scanning electron microscopy (SEM). The photophysical properties of samples were tested using UV-visible transmission (UV-vis) and fluorescence spectra; Using modified TiO2 thin film as the working electrode, titanium dioxide films interface parameters were calculated in simulated seawater such as flat-band potential, space charge layers carrier concentration as well as space-charge layer width by titanium dioxide semiconductor properties and Mott-Schotty theory. Finally photoelectric propertie of modified titanium dioxide is studied in a simulated seawater using cyclic voltammetry (U-I curve), open circuit potential test, Electrochemical Impedance Spectroscopy(EIS) and polarization curves with photoelectrochemical cell, comprehensive evaluation of its stainless steel substrate photogenerated protection performance.(1) Modified titanium dioxide, which is prepared titanium dioxide sol by adding PEG experiments showed that modification reduced the particle size and increase networking structure of titanium dioxide sol, made titanium dioxide crystal transition temperature to lower temperature direction and of good quality films were successfully prepared with porous structure of titanium dioxide thin films. The porous structure increased light reflection times in the film surface to improve light absorption and utilization. The porous structure of the film increased the contact area, at the same time was conducived to photogenerated-carrier transmission, which greatly improved the efficiency of photoinduced charge separation. Photoelectrochemical properties showed that the photoelectrochemical performance of modified titanium dioxide thin-film was improved significantly in simulated seawater. Comprehensive analysis conclusion of heat treatment temperature, porous structure, Best modified experimental conditions are below 500℃,1g PEG addition.(2)Fe-doped titanium dioxide was conducived to form small, stable particles sol. Fe-doped titanium dioxide was conducived to crystal transfer process, Fe-doped nano-titanium dioxide film decrease the grain size and crystallization excellent, film surface was more uniform and dense, Through optical performance analysis, absorption spectra of Fe-doped titanium dioxide turned red-shift; Fe-doped titanium dioxide can inhibit the photo-generated electron and hole recombination. By the Mott-Schottky curves analysis, Fe-doped titanium dioxide thin-film double-layer exist p-type and n-type micro-district co-exist; the electric field of the p-n junction is conducive to photocurrent generation in simulated sea water. Photoelectrochemical experiments confirm this conclusion, Fe-doped titanium dioxide thin film increase effectively the photocurrent and photogenerated electrons driving force, enhanced photogenerated cathode protection to stainless steel in simulated seawater. At the same test conditions, the amount of the best value is Fe/Ti ratio of 0.5% by synthesis of different quantity of the above-mentioned and comparation of properties of different Fe-doped.(3) N-doped titanium dioxide is conducive to form small, stable particles sol.. N doping transformation of crystalline titanium dioxide, N-doped nano-crystalline titanium dioxide film decreases the grain size and improvement significant film quality. Through optical performance analysis, Absorption spectra appear red-shift; in the context of significant absorption of visible light. Photoelectrochemical tests showed that in the visible light source, the, N-doped titanium dioxide samples had still electronic transition because N-doped changed after the electronic transition energy level, optical-carrier produced anodic photocurrent, can be effective on stainless steel substrate light cathodic protection. There exists an optimum amount of nitrogen doping. Experimental prove that the optimum N/ Ti ratio of the visible light photoelectric is 20%.
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