Dissertation > Excellent graduate degree dissertation topics show

Synthesis and Characterization of Modified TiO2Nanoparticles and Their Applications in Photocatalysis

Author: Muhammad Nasir
Tutor: ZhangJinLong
School: East China University of Science and Technology
Course: Applied Chemistry
Keywords: Photocatalysis Cerium Titania Carbon Nitrogen Sulfur Scandium Doping Codoping
CLC: O643.36
Type: PhD thesis
Year: 2013
Downloads: 72
Quote: 0
Read: Download Dissertation

Abstract


Titanium dioxide has been proved as a promising photocatalyst for the environmental cleanup in the field of photocatalysis because of its high activity, low cost, easy availability, non-toxicity and chemical robustness. However, there are certain shortcomings, which hinder its photoactivity such as its large band gap of3.2eV and fast recombination of electrons and holes. Therefore, there is a dire need to modify it in order to make it feasible for the photocatalysis under visible light irradiation and to reduce the recombination of electrons and holes.The main focus of the thesis was laid upon the single element doping and codoping with the nonmetals and transition metals in order to shift the absorption of TiO2towards the visible light region and reduce the recombination of photoexcited charge carriers to make it active under the visible light irradiation. The details of my works are as follows:1-In my first work, Ce and N codoped TiO2samples were successfully prepared by keeping in mind the advantages of Ce as a very powerful electron scavenger (even more than oxygen) with the ability to generate labile oxygen vacancies and bulk oxygen species, also N proved as a good candidate for the narrowing of the band gap and enhancement of the visible light response. The samples were prepared through the hydrothermal method by using less expensive precursors such as cerium nitrate, tetrabutyl orthotitanate (TBOT) and urea. These prepared samples were characterized by various techniques such as, X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Raman spectroscopy, X-ray Photoelectron Spectroscopy (XPS), Fourier Transformation Infrared Spectroscopy (FTIR), Thermogravimetric Analysis and Differential Thermal Analysis (TG/DTA), UV-Visible Diffuse Reflectance Spectroscopy (UV-vis DRS) and Photoluminescence Spectroscopy (PLS). The XRD and Raman spectra showed only anatase phase of TiO2for the single doped and codoped samples. The XPS of Ce showed the presence both Ce3+and Ce4+oxidation states. The PLS of the samples showed first decrease in the recombination centers when Ce was introduced in codoped TiO2with the maximum decrease for0.05Ce/N codoped TiO2and then started increasing with the increase of Ce in the samples. There have been founded a direct relationship between the number of recombination centers and photoactivity of the samples, which was measured by the decolorization of25mg/L solution of Acid Orange7(AO-7). The activities of codoped samples were highly increased by the incorporation of Ce with the maximum degradation exhibited by0.05Ce/N-TiO2sample.2-Inspired by the previous results of the idea of codoping Ce with the N, here in this part we tried the replacement of N with S, to check its effect on the efficiency of the degradation of the pollutant under the visible light. Hence, Ce and S codoped TiO2nanoparticles were prepared through simple sol-gel method and various characterization techniques were applied. The prepared samples showed the anatase type of structure with the increase of the specific surface area and decrease of the pore size with the increase in the Ce amount in the samples as indicated by the XRD and BET. The photoluminescence spectra revealed first decrease in the intensity of the spectra sync with the reduction of recombination of electrons and holes. Also, the Ce and S codoping induces the formation of Ti3+together with the increase in the surface hydroxyl radical with the increase in the amount of Ce in the samples. Thus, the increased photoactivity of the samples was attributed to the increase of the surface area, increase of the surface hydroxyl groups and decrease of the recombination of electrons and holes as well as the formation of Ti3+by the synergistic effect of the Ce and S.3-In the third part we replaced the S with the C in the Ce-TiO2to find out the effect on the photocatalytic activity of the prepared samples. The samples showed a slight increased in the surface area and decrease in the crystal sizes with the increase in the Ce amount in the samples. Also, the XPS of the samples indicated the decrease in the electron density on the Ti and an increase in the surface hydroxyl groups with the increase in the Ce concentration in the samples. The visible light photocatalytic activity of the prepared codoped samples was significantly increased as compared to the single C-doped TiO2due to the number of factors, such as a decrease of the crystal size and increase of the surface area, increase of the surface hydroxyl groups along with the decrease of the recombination of electrons and holes etc.4-In the fourth part we tried scandium and carbon codoped TiO2catalyst prepared through simple sol-gel synthesis method by using scandium nitrate as scandium dopant precursor, glucose as carbon and tetrabutyl orthotitanate as titanium precursor and calcined at450℃for3h. The XRD of the samples showed the decrease in the crystal size with the subsequent increase in the specific surface area as shown by BET. The UV-vis DRS displayed the blue shift in the absorption together with the PLS revealed first the decrease in the recombination of electrons and holes by the addition of the scandium and then after the certain optimum value the further increase of the scandium further increased the recombination of electrons and holes. The photocatalytic activity of the samples was investigated by the help of degradation of AO-7, which showed that the codoped samples significantly improved the photocatalytic activity.

Related Dissertations

  1. Preparation and Photocatalytic Properties for Water Decomposition of Titanate Photocatalyst,O643.36
  2. Preparation of Based on the Phenolic Resin of Activated Carbon and Adsorption-Photopcatalytical Character of Supported TiO2,TQ424.19
  3. Study of Interaction between Epoxy Molecules and Carbon Fiber Surface with Molecular Simulation,TB332
  4. Research on Welding Characteristics of CO2 Laser-GMA Hybrid Welding for Ultra-Low Carbon Bainitic Steel,TG456.7
  5. Experimental Research on Influence of Coal Reburning Reaction Conditions on NO_x Reduction by Non-Catalytic Reduction of Ammonia,X701
  6. Preparation and Properties of Silicon Carbon Anode for Lithium Ion Battery,TM912.9
  7. The Preparation and Research of Magnetically Separable TiO2 Photocatalyst Nanofibers,TB383.1
  8. Cultivation and Effects of Environmental Factors on Carrying WSSV Virus of Litopenaeus Vannamei,S945
  9. The Study about Carrying Out Low-carbon Education in the Teaching of Geography in the Middle School,G633.55
  10. Methane and Carbon Dioxide Fluxes from Spartina Alterniflora Marsh in Minjiang River Estuary,X502
  11. Study on Activated Carbon Supported Cerium Catalytic Ozone Oxidation of Chloramphenicol,X703
  12. Effects of Light, Temperature and Nitrogen on the Growth of Three Kinds of Aquatic Plants,Q945
  13. The Study of Preparation and Photocatalytic Activity of TiO2 by Electrospinning,O614.411
  14. Under microaerobic conditions closed calcium carbide furnace exhaust COS gas adsorption purification,X781
  15. Study and Preparation of BaTiO3-based NTC Ceramic Thermistors,TQ174.1
  16. Design, Synthesis and Antitumor Activities Study of Quinoxaline-1,4-dioxide Derivatives,R914
  17. The Preparation and Electrochemical Tests of Carbon Foam,O613.71
  18. The Preparation of Polyaniline-Metal Complex and the Study on Its Catalytical Property,O634
  19. First- principles calculations of doped anatase titanium dioxide photocatalytic properties,O643.36
  20. The Research on the Formation and Application of Carbonaceous Mesophase,TQ127.1
  21. Study on the Synthesis and Adsorption Behaviour of Chitosan Derivative,TS254.9

CLC: > Mathematical sciences and chemical > Chemistry > Physical Chemistry ( theoretical chemistry ),chemical physics > Chemical kinetics,catalysis > Catalytic > Catalyst
© 2012 www.DissertationTopic.Net  Mobile