Fabrication And Photoelectrocatalytic Degradation Properties Of Vib Race Of Elements-doped Titanium-film Electrodes

The techniques of liquid phase deposition, electrochemical oxidation, Sol-hydrothermal method and dye sensitizied were developed for the preparation of TiO2doped with sexivalent metal ions in this study, respectively. And doped TiO2have been used for degrading waste water under UV and visible light. The characterization of modified TiO2, such as the crystal, energy band, surface morphology and photoelectrochemistry ability, were characterized with X-ray diffraction (XRD), X-ray photoelectron dispersive (XPS), transmission electron microscopy (TEM), field scanning electron microscopy (FSEM), FT-IR Spectrometer (FTIR), UV-Vis and photoelectrochemistry analysis. On the other hand, first principle calculation has been used to get the energy band and density of states of doped TiO2so that it could be explained the essence of doped TiO2. There are some main results are as follows:(1) Liquid phase deposition method was used to fabricate W, Cr and Mo doped TiO2electrode, respectively. Compared with pure TiO2, the photocatalytic activity (PC) of doped TiO2has been developed. After theramal treatment at400℃, the photoelectrocatalytic (PEC) degradation of MO under UV and applied1.5V at the same time over W-STiO2, Cr-STiO2and Mo-STiO2electrode were55%,47.9%and38.3%, respectively. The5%W-STiO2film showed the highest degradation efficiency. Therefore, the PEC degradation of dodecyl-benzenesulfonate (DBS) was tested over it and the PEC efficiency up to92%in case of+1.0V anodic bias potential and visible light were simultaneously applied. The effects of anodic bias potential, initial pH value, and initial concentration of DBS on the PEC degradation of DBS were investigated. On the other hand, the PEC efficiency of MO over Cr0.4%-Fe0.7%-TiO2electrode showed the best degradation effieciency up to58%within2h under UV because of the NP heterojunction construction in the TiO2film.(2) Highly ordered sexivalent metal ions doped TiO2nanotube (NT) were prepared by the electrochemical oxidation of Ti substrate in glycerol/fluoride electrolyte solution. The PEC activity of doped NT has been improved.0.005M W-NT sintered at400℃showd the best PEC efficiency of MO up to78.9%within2h under UV illumination and1.5V potential simultaneously applied. On the other hand,0.015M Cr-NT have also showed high PEC efficiency of MO up to about80%. The XRD paterns of Cr-NT showed that anatase phase of TiO2dominated the crystal structure on Cr-NT enver after sintered at600℃. It was good for PEC reaction and also means that the dopant has been doped into TiO2lattice successfully.(3) Sol-hydrothermal method was used to fabricate the sexavalence metal ion (VIB) and nitrogen (N) co-doped titanium oxide (TiO2) nanoparticles. N-TiO2sintered at600℃showed the better PC activity and the degradation efficiency of MO achieved totally degraded within30min under UV illumination and51.5%under visible light within2h. The codoped W/N-TiO2showed the better PC activity. The PC degradation efficiency of MO was68.1%over W/N-TiO2within2h under visible light illumination. The pictures of TEM showed that the shape of W/N-TiO2has been clearly changed. The crystal lattice of TiO2and W/N-TiO2were0.349nm and0.433nm supported by HRTEM, respectively. It was demonstrated that the dopant has been doped into TiO2lattice and improved PC activity was improved.(4) N-TiO2and W/N-TiO2nanoparticles electrode have been sensitized with sodium-iron-chlorophyllin (Fe-chl) and used for PEC degradation of MO under visible light illumination. When the concentration of Fe-chl at2mM, the sensitized W/N-TiO2showed the highest PC efficiency of MO at64.3%within4h under visible light illumination due to Fe-chl could adsorb visible light and the porphyrin molecular could be excited with visible light which was available for PEC activity of TiO2.(5) The energy band structure of doped TiO2have been calculated with first principle. The conduction and valence band edge of doped TiO2have been reconstructed at a lower location compared with undoped TiO2. The band gap of TiO2, N-TiO2, W-TiO2and W/N-TiO2were3.01eV,2.77,2.85and2.62eV, respectively. The high PC activity of W/N-TiO2was due to the conduction and valence band were controlled by3d orbit of W and Ti,2p orbit of N and O, respectively.