Micromixing-assisted Fabrication And Photo-Electrochemical Performance Investigation Of TiO₂ Photoanodes With Visible Light Response

TiO₂ semiconductor is expected as the most important photoanode material applied for the novel green and environmental friendly metal anticorrosion technology,because of its unique photoeleetrochemical properties.Nevertheless,the inherent disadvantages of the TiO₂,lies in their limited visible light utilization and quajntum yield,have extremely restricted their practical applications.Moreover,the synthesis of well-ordered TiO₂ thin films from alkaline solution is still challenging due to the fact that the traditional mixing process possesses several disadvantages in controllable homogenous chemistry.Therefore,the work described in this paper is devoted to the preparation of TiO₂ thin film photoanodes from alkaline solutions with controllable morphology.In addition,several reactants are employed to doping anions and cations into the TiO₂ product.The effects of the operation conditions and doping modifications on the photoelectrochemical performance of the Ti02 thin film photoanodes are investigated based on the numerical simulation and experimental measurements.The main research contents and results of this work were summarized as follows:1.Based on the use of home-built micromixer,the liquid-liquid reaction system with fast precipitation process is investigated through numerical simulation and experimental measurements.It is found that the micromixer is advantageous for the ultrafast mixing at the microscale,and the homogeneous chemistry in the reactant solutions can be efficiently inhibited.The initial iulet velocity of the reactant solutions and the diameter of the microfiltration membrane have major impacts on the average size and distribution of the primary nano particles.2.A novel micromixing-assisted route is designed to efficiently synthesize well-ordered anatase-TiO₂ thin films from alkaline solutions at low temperatures.The experimental results indicate that the surface morphology of the product can be controlled by carefully operating the parameters of micromixing and liquid phase deposition process.The quality of the of the surface morphology can be significantly increased when the microxming mass flow rate,deposition time and preparation temperature is 0.60 m/s,50 min and 80℃,respectively.3.The TiO₂ thin films photoanodes with various N contents are successfully synthesized through adjusting the concentration of the N-containing compounds.It is found that the N is well incorporated into the TiO₂ lattice and thus shifting the absorption zone of the TiO₂ to the visible domain.Intriguingly,we find that the concentration of CO（NH2）2 plays a significant role in affecting the films growth rate and the N-doping capability.The as-prepared N-TiO₂ photoanodes exhibit excellent visible light-induced photoelectrochemical activities and can provide an effective photogenerated cathodic protection for the eoupled metal electrode.4.The TiO₂ thin films photoanodes co-doped with N/AI and N/Fe are successfully synthesized by using Al（NO3）3 and FeCl3 as Al and Fe source,respectively.The results indicate that the Ti4+ in TiO₂ lattice is substituted by Al3+ and Fe3+ ions.The synergistic effect of N/Al and N/Fe co-doped has the benefit to restrain grain growth,as well as improving the visible light response activity of the TiO₂ photoanodes.Moreover,the recombination rate of photogenerated electron-hole is efficiently restricted due to the impregnation of Al and Fe.