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Chemical Doping of Metal Oxide Nanomaterials And CHEMICAL DOPING OF METAL OXIDE NANOMATERIALS AND CHARACTERIZATION OF THEIR PHYSICAL-CHEMICAL PROPERTIES by JUNWEI WANG Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy Dissertation Advisor: Dr. Clemens Burda Department of Chemistry Case Western Reserve University May, 2012 CASE WESTERN RESERVE UNIVERSITY SCHOOL OF GRADUATE STUDIES We hereby approve the thesis/dissertation of ______________________Junwei Wang__________________________ Candidate for the ________PhD_______________________degree*. (signed) __________Carlos E. Crespo Hernández___________________ (chair of the committee) ___________Alfred B. Anderson__________________________ ____________John E. Stuehr_____________________________ _____________Jeffery Dyck_____________________________ _____________Clemens Burda___________________________ _____________________________________________________ (date)________3/28/2012_______________ *We also certify that written approval has been obtained for any proprietary material contained therein. TABLE OF CONTENTS TABLE OF CONTENTS .............................................................................................. 1 LIST OF TABLES ........................................................................................................ 4 LIST OF FIGURES ...................................................................................................... 5 ACKNOWLEDGEMENTS ......................................................................................... 13 LIST OF ABBREVIATIONS ...................................................................................... 14 ABSTRACT ............................................................................................................... 16 CHAPTER 1 INTRODUCTION ................................................................................. 18 1.1 MOTIVATION: ENERGY AND ENVIRONMENT CRISIS ............................................... 18 1.2 POTENTIAL SOLUTIONS: PHOTOCATALYSIS .......................................................... 20 1.3 CURRENT RESEARCH ON METAL OXIDES AS PHOTOCATALYSTS ............................... 24 1.4 ABOUT THIS DISSERTATION ................................................................................. 28 1.5 REFERENCES ...................................................................................................... 30 CHAPTER 2 HYDROTHERMAL NITROGEN-DOPED TITANIUM DIOXIDE WITH SWITCHABLE SURFACE WETTABILITY .............................................................. 31 2.1 INTRODUCTION ................................................................................................... 31 2.2 EXPERIMENTAL PROCEDURES .............................................................................. 32 2.3 RESULTS AND DISCUSSION................................................................................... 34 2.4 CONCLUSION ...................................................................................................... 41 2.5 REFERENCES ...................................................................................................... 42 1 CHAPTER 3 MODIFYING TITANIUM DIOXIDE WITH TUNGSTEN..................... 44 3.1 INTRODUCTION ................................................................................................... 44 3.2 EXPERIMENTAL PROCEDURES .............................................................................. 45 3.3 RESULTS AND DISCUSSION................................................................................... 47 3.4 CONCLUSION ...................................................................................................... 52 3.5 REFERENCES ...................................................................................................... 53 CHAPTER 4 A COMPARATIVE STUDY OF COBALT ION DOPING OF TIO2 AND TIO2-XNX AT THE NANOSCALE: EVIDENCE FOR ROOM TEMPERATURE CONVERSION FROM ANATASE TO RUTILE PHASE .......................................... 54 4.1 INTRODUCTION ................................................................................................... 54 4.2 EXPERIMENTAL PROCEDURES .............................................................................. 55 4.3 RESULTS ............................................................................................................ 56 4.4. DISCUSSION ...................................................................................................... 71 4.5 REFERENCES ...................................................................................................... 76 CHAPTER 5 FACILE CHARGE TRANSFER, PHASE TRANSFORMATION, AND THE ANALOG OF NITROGEN FIXATION IN HEAVILY IRON ION DOPED TITANIUM OXIDE AND OXYNITRIDE NANOCOLLOIDS ................................... 79 5.1 INTRODUCTION ................................................................................................... 79 5.2 EXPERIMENTAL PROCEDURES .............................................................................. 80 5.3 RESULTS ............................................................................................................ 83 5.4 DISCUSSION ..................................................................................................... 106 5.5 CONCLUSION .................................................................................................... 110 2 5.6 REFERENCES .................................................................................................... 111 CHAPTER 6 SYNTHESIS AND CHARACTERIZATION OF NANO-SCALED GALLIUM, NITROGEN CO-DOPED TITANIUM DIOXIDE WITH HIGH NITROGEN CONCENTRATION............................................................................. 114 6.1 INTRODUCTION ................................................................................................. 114 6.2 EXPERIMENTAL PROCEDURES ............................................................................ 115 6.3 RESULTS .......................................................................................................... 117 6.4 CONCLUSION .................................................................................................... 126 6.5 REFERENCES .................................................................................................... 127 CHAPTER 7 INTERACTIVE IRON-SILICON OXIDATION/REDUCTION PROCESSES ON FUMED SILICA .......................................................................... 129 7.1 INTRODUCTION ................................................................................................. 129 7.2 EXPERIMENTAL PROCEDURES ............................................................................ 130 7.3 RESULTS .......................................................................................................... 131 7.4 CONCLUSION .................................................................................................... 146 7.5 REFERENCES .................................................................................................... 148 CHAPTER 8 SUMMARY AND OUTLOOK ............................................................ 149 BIBLIOGRAPHY ..................................................................................................... 151 3 LIST OF TABLES Table 2.1 Relative XRD peak intensities (at 2θ = 25.2º, 53.8º and 55.0º) for the prepared samples and standard anatase TiO2 (For comparison, the intensities of the peak at 2θ = 55.0º are set to be 1.0). ........................................................................................ 36 Table 2.2 Contact angle measurements for the N-doped TiO2 samples before and after visible-light illumination ............................................................................................. 39 Table 4.1 Composition of the prepared samples ........................................................... 57 Table 5.2 2s and 2p Core level XPS Binding Energies as Function of Fe2+ Doping Level (eV) - for several mole fractions (peak intensities for 2p3/2 (2p3) and 2p1/2 (2p1) are indicated) .................................................................................................................... 88 Table 5.3 Calculated 2s and 2p Binding Energies in eV. .............................................. 89 Table 6.1 Particle size calculated based on Scherrer equation. .................................... 120 Table 6.2 Percentage and Binding Energies of N1s in the samples based on XPS analysis. ................................................................................................................................. 122 Table 7.1 XPS de-convoluted peaks for Fe Cab samples using Gaussian functions ..... 135 Table 7.2 XPS results of the Silicon 2p in the Fe-CAB-O-SIL samples ...................... 136 Table 7.3 Predicted and Observed Fe(II) and Fe(III) amounts on the Cab-O-Sil Surface. ................................................................................................................................. 140 Table 7.4 Detailed analyses of IR peaks. ................................................................... 143 4 LIST OF FIGURES Figure 1.1 Crude oil prices from January 2nd, 1986 to March 6th, 2012. Data from http://www.eia.gov/dnav/pet/hist/LeafHandler.ashx?n=PET&s=RWTC&f=A ................................................................................................................ 19 Figure 1.2 Average gasoline prices in US from 1986 to 2011. ....................................... 20 Figure 1.3 Illustration of photocatalytic
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