Dissertation > Excellent graduate degree dissertation topics show

Study on the Doped Anatase TiO2 by First-principle Calculation

Author: WanWei
Tutor: WangHaiDong
School: Central South University
Course: Materials Science
Keywords: First-principles Materials Studio Anatase TiO2 Doping Electronic structure Photocatalytic Activity
CLC: O471
Type: Master's thesis
Year: 2011
Downloads: 110
Quote: 0
Read: Download Dissertation

Abstract


TiO2 as semiconductor photocatalytic oxidation technology, the use of solar energy oxidation at room temperature decomposition of pollutants, is a the environmental governance new technology has broad application prospects. However, as a wide band gap semiconductor TiO2 only accounts for about 3% of the UV irradiation in sunlight response, solar energy utilization is low. By regulation, so as to obtain the band gap of TiO2 Doped TiO2-based visible light photocatalyst can respond to visible light has been the target of people's efforts. Using first-principles based on density functional theory (DFT) plane wave pseudopotential method, Applied Materials Studio Materials simulation software, through the establishment of the supercell doping model of anatase phase TiO2, metal ions (Co2, Fe3 Zr4 V5, W6) replace Ti4 doping of the lattice spacing and metal ions doped S under three different doping doping Fe3-S2-co-doped anatase TiO2 electronic structure and optical properties of the analog calculations. The thesis main conclusions are as follows: (1) anatase TiO2 the valence band and the conduction band is mainly composed of the O 2p orbital and Ti 3d orbital contribution to strong UV absorption peak at 220nm, optical absorption thresholds at 400nm near. (2) metal ion doping, the formation of impurity levels in the different ions and different doping position different, have different effects on TiO2 energy band structure produced. The formation of the impurity level Metal Co. 3d, Fe 3d, Zr 4p and 4d, V 3p and 3d W5p and 5d orbit contribution. Metal ion doping leads to a red shift of the absorption edge in the absorption spectra of TiO2 or the emergence of new absorption peak in the UV - visible. Light metal ion substitution doping the response energy threshold from small to large order: Fe3, Co2, V5, Zr4, W6 doping. Which of Co2, Fe3 Zr4, V5 doped absorption edge with redshift, W6 doping strong new absorption band appears in the visible region; metal gap doped TiO2 in the visible region of 400-600nm range the large absorption coefficient. (3) three S-doped (cation substitution anion substitute doping gap) in the form of the local area above the valence band items there are S 3p impurity states in the impurity states in the band gap of the doped TiO2 regulation; valence electron transitions from the valence band to the conduction band shift by the S 3p transitions to the conduction band, resulting in the S-doped TiO2 absorption edge redshifts. S2-anion impurity state level position doping impurity states position lower than the corresponding concentrations S6 cation showed stronger photocatalytic activity modified light response threshold up to 600nm. Gap doped: is unique in that the clearance S doping two alternative doped produce an energy band transitions as the valence electron transition impurities, having a higher response in the visible range, the visible light response wave up to 600 - 700nm. (4) Fe3-S2-co-doped with a structure similar to Fe3 S2-single ion doped superimposed. Composite valence band top and to local in the Fe 3d impurity states in the band gap of TiO2 regulation under the bottom of the conduction band; across the Fermi surface impurities Fe 3d and S 3p orbital contribution to the state, to change the electronic transition process, indirectly reduce the energy required electronic transitions. Codoped modified optical response compared to the single-ion modified and a further expansion of the light response range widened to 600-700nm long wave visible region. The simulation results clarify the different ions with the doping concentration of TiO2 electronic structure of the role of law, reveals a modified TiO2 photocatalytic activity of different ions and different doping to improve the internal mechanism of doping modified experiments to explore the ion The study provides a theoretical basis.

Related Dissertations

  1. Preparation and Photocatalytic Properties for Water Decomposition of Titanate Photocatalyst,O643.36
  2. Studies on Synthesis, Characterization and Properties of Fe-V Co-doped TiO2 Catalyst,O614.411
  3. The Study of Preparation and Photocatalytic Activity of TiO2 by Electrospinning,O614.411
  4. Study and Preparation of BaTiO3-based NTC Ceramic Thermistors,TQ174.1
  5. First- principles calculations of doped anatase titanium dioxide photocatalytic properties,O643.36
  6. Investigation of Fabrication, Characterization and Property of Fuctional Titanium Dioxide Nanoporous Materials,TB383.1
  7. Preparation of One-dimensional Nano TiO2 and Study on the Decolorization of Dyeing Wastewater,TB383.1
  8. First-Principles Studies of Blacl Phosphorus and LiMn2O4 as Electrode Material for Lithium Ion Batteries,TM912
  9. First-Principles Studies of Cathode Material LiMO2 （M=Co, Ni, Mn） of Lithium Ion Batteries,TM912
  10. Iron, lanthanum -doped nano TiO \u003csub\u003e 2 \u003c/ sub\u003e Preparation and photocatalytic properties,O614.411
  11. First-Principles Studies of Cathode Material Srn+1TinO3n+1（n=1,2,3,∞） for Solid Oxide Fuel Cell,TM911.4
  12. Eu- doped α-SiAlON phosphor First-principles study,TB34
  13. First-principles study of the structure and optical properties of the high-pressure alkali metal (Li, Na, K),O521.2
  14. A Study for Structure and Properties of OsnN0, ± （n=1-6） Clusters,O641.1
  15. Influence of Doping Effect on Zinc Oxide by First Principles Studies,O614.241
  16. First-principles Study on the Influence of Doping on the Strength of Super-hard Materials,O469
  17. Doped Modification and Application of Titania Photocatalyst,O643.36
  18. Preparation and Properties of Crystalline Glaze for Low Temperature and Fast Firing,TQ174.65
  19. Research on Luminescence of Nanoporous Glass Composite Materials,TB383.1
  20. First-principles Study on Magnetic and Optical Properties of Rutile TiO2,O614.411
  21. Preparation of Zeolite Doping Nano-TiO2 and Research of the Photocatalytic Properties,TB383.1

CLC: > Mathematical sciences and chemical > Physics > Semiconductor physics > Semiconductive Theory
© 2012 www.DissertationTopic.Net  Mobile