by Leung Yat-chor, Calvin. / Includes bibliographical references / Thesis (M.Ph.)--Chinese University of Hong Kong, 1984

by Kwok Chun-kiu. / Thesis (M.Ph.)--Chinese University of Hong Kong, 1987. / Bibliography: leaves 69-74.

Leung Cheuk-wan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references. / Abstracts in English and Chinese. / Abstract --- p.i / Abstract (Chinese) --- p.ii / Acknowledgement --- p.iii / Table of Contents --- p.v / Lists of Tables --- p.ix / Lists of Figures --- p.x / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- TiO2 Photocatalysis --- p.1 / Chapter 1.1.1 --- Mechanisms of TiO2 Photocatalysis --- p.1 / Chapter 1.2 --- Visible Light Photocatalyst --- p.4 / Chapter 1.2.1 --- Preparation of Visible Light Ti02 Photocatalysts --- p.5 / Chapter 1.2.1.1 --- Dye Sensitization --- p.5 / Chapter 1.2.1.2 --- Metal Doping --- p.6 / Chapter 1.2.1.3 --- Coupling of Semiconductors --- p.6 / Chapter 1.2.1.4 --- Nonmetal Doping --- p.7 / Chapter 1.3 --- Enhanced TiO2 Photocatalytic Activity under UV Light --- p.8 / Chapter 1.3.1 --- Preparation of TiO2 Photocatalyst with Enhanced Activity in UV Light --- p.8 / Chapter 1.3.1.1 --- Loading of Metal --- p.8 / Chapter 1.3.1.2 --- Impurity Co-doping --- p.9 / Chapter 1.3.1.3 --- Morphological Control --- p.10 / Chapter 1.3.1.4 --- Increasing Surface Area --- p.10 / Chapter 1.4 --- Summary --- p.11 / Chapter 1.6 --- Aim of This Research and its Significance --- p.12 / Chapter 1.7 --- References --- p.13 / Chapter Chapter 2 --- Preparation of N-doped TiO2 with Enhanced Surface Area: A Detailed Characterization and Mechanism --- p.19 / Chapter 2.1 --- Introduction --- p.19 / Chapter 2.2 --- Experimental --- p.21 / Chapter 2.2.1 --- Materials and Catalyst Preparation --- p.21 / Chapter 2.2.2 --- Characterization --- p.21 / Chapter 2.2.3 --- Photocatalytic Activity --- p.23 / Chapter 2.3 --- Results and Discussion --- p.24 / Chapter 2.3.1 --- XRD Analysis --- p.24 / Chapter 2.3.2 --- UV-Vis Absorption Spectroscopy and Bandgap Energies --- p.27 / Chapter 2.3.3 --- N2 Sorption Analysis --- p.29 / Chapter 2.3.4 --- SEM Analysis --- p.33 / Chapter 2.3.5 --- TEM Analysis --- p.35 / Chapter 2.3.6 --- FT-IR Spectroscopy --- p.36 / Chapter 2.3.7 --- Raman Spectroscopy --- p.39 / Chapter 2.3.8 --- XPS Studies --- p.44 / Chapter 2.3.9 --- PL Measurements --- p.49 / Chapter 2.3.10 --- Photocatalytic Activity Measurements --- p.50 / Chapter 2.3.11 --- Advantages of Using Urea as a N-doping Source --- p.54 / Chapter 2.3.12 --- Mechanisms for N-doping --- p.56 / Chapter 2.4 --- Conclusions --- p.58 / Chapter 2.5 --- References --- p.59 / Chapter Chapter 3 --- Preparation of Nanoporous Interstitial B-doped TiCO2 with Enhanced Photocatalytic Activity --- p.63 / Chapter 3.1 --- Introduction --- p.63 / Chapter 3.2 --- Experimental --- p.65 / Chapter 3.2.1 --- Materials and Catalyst Preparation --- p.65 / Chapter 3.2.2 --- Characterization --- p.66 / Chapter 3.2.3 --- Photocatalytic Activity --- p.67 / Chapter 3.3 --- Results and Discussion --- p.68 / Chapter 3.3.1 --- XRD Analysis --- p.68 / Chapter 3.3.2 --- UV-Vis Absorption Spectroscopy and Bandgap Energies --- p.71 / Chapter 3.3.3 --- N2 Sorption Analysis --- p.73 / Chapter 3.3.4 --- SEM and TEM --- p.76 / Chapter 3.3.5 --- FT-IR Spectroscopy --- p.80 / Chapter 3.3.6 --- Raman Spectroscopy --- p.82 / Chapter 3.3.7 --- PL Measurements --- p.84 / Chapter 3.3.8 --- XPS Studies --- p.85 / Chapter 3.3.9 --- Photocatalytic Activity Measurements --- p.89 / Chapter 3.3.10 --- State and Form of Boron in TiO2 Lattice and its Effects --- p.91 / Chapter 3.4 --- Conclusions --- p.93 / Chapter 3.5 --- References --- p.94 / Chapter Chapter 4 --- Conclusions --- p.97

Anodised titanium dioxide (titania, TiO2) nanotubes have been widely studied over the last few years, following the discovery in 1999 of nanoporous TiO2 films prepared via anodisation in aqueous solution containing small quantities of hydrofluoric acid. The synthesis of nanotubular titania by anodisation, a relatively simple and low cost technique, represents a motivation for scientists, considering the impact that such a material could have on a variety of applications, including gas-sensing, biomedical, photocatalysis, and photovoltaics. This research project has focused on the optimisation of the growth process of anodic titania nanotubes, both in an aqueous (NaF/Na2SO4) and an organic (Glycerol/NaF) electrolyte containing fluorine ions. Reproducibility and the ability to generate anodic films having a thickness of several micrometers are fundamental steps to be achieved before investigating any possible application of the nanotubes. To characterise the anodic specimens and build upon the general lack of information on the growth mechanism, a comprehensive study of the different stages of the process has been performed, using Scanning and Transmission Electronic Microscopy (SEM and TEM). Among the questions to be addressed in this thesis, is to establish whether the anodic film undergoes a transition from pores to tubes or develops a tubular morphology from the beginning of its growth. Additional characterisation of the anodisation process includes the study of current-time curves, and chemical composition analysis of the anodic layers using X-ray Photo-Electron Spectroscopy (XPS). The thermal stability of the nanotubes and structural/morphological changes as a result of heat treatment at different temperatures were also studied, again using SEM, TEM, XPS and Raman spectroscopy. The final part of the thesis is dedicated to preliminary work on the use of anodised TiO2 nanotubes in Dye Sensitized Solar Cells (DSSCs), along with suggestions for future works and general conclusions.

by Lin Jun. / "Nov. 28, 2000." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Another study was to prepare hierarchically mesoporous titania materials with well-defined grape-like morphology in the presence of a triblock copolymer using bubbling-mediated hydrolysis approach. The effects of bubbling time and calcination temperature on both physicochemical and photocatalytic properties were investigated. / Furthermore, thermally stable ordered mesoporous CeO2/TiO 2 visible photocatalysts were prepared by the evaporation-induced self-assembly method. Introducing highly dispersed CeO2 species into the mesoporous TiO2 framework could effectively extend the response of TiO 2 to visible light region and improve the thermal stability of the mesoporous TiO2. / In addition, visible-light-driven mesoporous TiO2-xN x photocatalysts were developed via in-situ pyrolysis of the product from a chelation reaction between TiCl4 and ethylenediamine under sonication. The effects of ultrasound bombardment on the physicochemical properties and photoactivity of mesoporous TiO2-xNx were discussed. / Part I. Ordered and well crystallized cubic Im 3¯ m mesoporous Cr-TiO2 photocatalysts were fabricated through EISA (evaporation induced self assembly) process. The as prepared photoactalysts exhibited very strong photoactivity in the degradation of methylene blue under visible light irradiation owing to the excitation of 3d electron of Cr3+ to the conduction band of TiO2. / Part II. New approaches have been developed for the fabrication of visible light photocatalysts, BiVO4 and Bi 2WO6. In the case of BiVO4, ordered mesoporous bismuth vanadate (BiVO4) crystals were synthesized via nanocasting method. Compared to the conventional BiVO4, the product exhibited superior photocatalytic performance in the photochemical degradation of methylene blue and photocatalytic oxidation of NO gas in air under visible-light irradiation. In addition, hierarchical flower-like Bi2WO6 was synthesized via microwave-assisted route. Compared to the samples prepared by the hydrothermal method, the products exhibited excellent photocatalytic activities of degrading methylene blue and photocatalytic oxidation of NO gas in air under visible light irradiation. The effects of microwave irradiation on both physicochemical and photocatalytic properties of the as prepared products were investigated. / Two different types of porous visible light photocatalysts were studied in this thesis. The first part reports on the improvement of photocatalytic performance of porous TiO2 through metal/nonmetal doping and morphology controlling. The second part describes the fabrication of porous non-TiO2 photocatalysts including BiVO4 and Bi2WO6. / . / Adviser: Jimmy C. Yu. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3527. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Studies were conducted into the mechanism and kinetics of the dissolution of synthetic zinc sulfide and zinc concentrate in aqueous solutions containing sulfur dioxide.Experiments at ambient temperature established that the dissolution of ZnS in aqueous solutions of sulfur dioxide proceeds via acidic non-oxidative dissolution and not by direct reaction of the sulfide with S02(aq). The non-oxidative dissolution reaction generates H2S(aq) or HS-(aq) species which are thought to rapidly react with sulfurous acid species, S02(aq) or HS03-(aq), to possibly produce initially sulfane monosulfonates as intermediates, followed by sulfane disulfonates and elemental sulfur. The formation of sulfane monosulfonates is postulated based upon inhibition observed in ZnS / S02 leaches which is not attributable to either H2S(aq) or occlusion elemental sulfur.At elevated temperatures (100oC - 200oC) the rate of ZnS dissolution in sulfurous acid is affected by the thermal decomposition of sulfurous acid, which produces sulfuric acid, which leaches the mineral non-oxidatively. Increasing the temperature increases the rate of thermal decomposition of sulfurous acid and consequently, the rate of sulfuric acid formation, increasing the rate of ZnS dissolution.The kinetics of the dissolution of ZnS in solutions of sulfuric acid and sulfur dioxide were investigated at temperatures up to 200oC. At 100oC and 150oC, the dissolution of ZnS in H2SO4 was found to obey the relationd[Zn2+]/dt = kfAs[H+] krAs[H2S(aq)]1/2[Zn2+]1/2and equilibria and rate constants for the ZnS / H2S04 reaction were obtained over the range, 100oC to 200oC. The activation energies of the forward and reverse reactions were found to be 56 +/- 11 kJ mol-1 and 45 +/- 15 kJ mol-1, respectively. The equilibrium constants were 4.99x10-4, 1.26x10-3 and 2.83x10-3 at 100oC, 150oC and 200oC, respectively.In the presence of added S02, ++ / at low ZnS pulp density (0.5 g L-1), the rate of ZnS dissolution in sulfuric acid increased due to the removal of H2S(aq) by reaction with S02(aq) or HS03-(aq). However the increase in rate was much less than that expected for the complete removal of H2S(aq). As with leaches of ZnS in sulfurous acid at ambient temperature, the inhibition was not attributable to the presence of residual H2S(aq) or to occlusion of unreacted ZnS by elemental sulfur, but is thought to be due to aqueous species that are like "H2S", in that they may react with Zn2+ to reprecipitate W.To this end, sulfane monosulfonates have again been postulated. The rate of ZnS dissolution, under conditions of low pulp density, was independent Of S02 concentration, suggesting that under these conditions the rate of the H2S / S02 reaction is also independent of the S02 concentration.At higher pulp densities (200 g L-1), similar to those expected in an industrial application, synthetic zinc sulfide leached rapidly in H2S04 / S02 solutions to approximately 60% zinc extraction, but was then inhibited by the large amounts of sulfur that formed. These caused agglomerates of zinc sulfide and elemental sulfur to form, even at temperatures below the melting point of sulfur, reducing the surface area of zinc sulfide available for reaction.Leaches of zinc concentrate at low pulp densities in H2S04 / S02 solutions and at temperatures above sulfur's meting point, were inhibited by the formation of molten sulfur. In contrast to synthetic zinc sulfide, zinc concentrate is readily wet by molten sulfur. Three surfactants orthophenylenediamine, quebracho and sodium ligninsulfonate were found to be reasonably effective in preventing molten sulfur from occluding the mineral surface. At high pulp densities, the H2S04 / S02 leach solution was unable to effect, the extraction of zinc from a zinc concentrate beyond approximately ++ / 10%.Integral S02 / H2S04 leaching of zinc concentrate was found not to be a commercial prospect. However, sidestream processing of zinc concentrate in an acid leach stage followed by reaction of generated H2S with S02 from the roasting stage to produce elemental sulfur may be viable.

<p>This thesis considers the effect of a large scale wind power introduction into an electricity system and the focus has been on the carbon dioxide emissions. Two different systems were studied, the Swedish and the Danish electricity system. When studying the Swedish electricity system different scenarios were created to see what might happen with the CO₂ emissions with an introduction of a large amount of wind power. The model that was used is based on parameters such as regulating power, transmission capacity, export possibility, and the electricity generation mixes in the Nordic countries. Given that the transmission capacity is good enough, the conclusion is that the carbon dioxide emissions will be reduced with a large scale introduction of wind power. In the Danish electricity system wind power is already introduced to a large extent. The main purpose here was to investigate the development of the CO₂ emissions and if it is possible to decide the actual change in carbon dioxide emissions due to the large scale introduction of wind power. The conclusions to this part are that the CO₂ emissions per kWh produced electricity have decreased since the electricity generation mix has changed but the total amount of CO₂ emissions fluctuates depending on weather, in a dry year less hydro power from Norway and Sweden can be used and more electricity from the fossil fuelled CHPs are generated. It has not been possible to determine the influence of the wind power on the CO₂ emissions.</p>

Graduation date: 1968

The carbon is photoelectron spectrum of CO��� has been measured with very high photon energy resolution. The natural lifetime of the carbon is hole state has been determined from a series of spectra taken at photon energies of 308, 320, and 330 eV. The measured values of the lifetimes show a dependence on photon energy; this is attributed to failure of the theory of post-collision interaction to predict correctly the observed electron spectrum near threshold. The lifetime widths reported here are critically compared with those values from the literature that are based on other spectroscopic techniques. The oxygen 1s photoelectron spectrum for CO��� has been calculated using ab initio electronic structure theory, a localized hole simulated by the equivalent-cores approximation, and the harmonic oscillator approximation. There is good agreement between the calculated spectrum and a recently reported experimental spectrum. / Graduation date: 1999