Thesis (Ph.D.)--Oklahoma State University, 2006. / Adviser: Allen Apblett. Includes bibliographical references.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment for the degree of Master of Science in Chemistry. Johannesburg 2016. / In the current study, different platinum-hollow carbon sphere catalysts were synthesized for use as electrocatalysts in low temperature fuel cells such as proton exchange membrane fuel cells (PEMFCs). The support material was synthesized via a hard templating method using mesoporous silica (synthesized using a modified Stöber method) as a sacrificial template. In fuel cells, one aim is to ensure that as much platinum as possible is present on a given electrode while keeping the entirety of the catalytic layer as thin as possible (i.e. with the minimum amount of carbon). One approach to achieving this was to make the hollow carbon spheres as small as possible, starting of course with the templating material. It was found that tailoring the molar ratios between the two co-solvents (that is water and ethanol) during Stöber synthesis was the key to achieving particles as small as approximately 150 nm with a uniform shape, size, and significant yields of up to 5.00 g. Another focal point in terms of the template material was achieving a silica structure that consisted of a solid core, and a distinctly mesoporous shell. Two different surfactants were explored in order to fabricate these structures; namely octadecyltrimethoxysilane (C18TMS) and cetyltrimethylammonium bromide (CTAB). It was found that of the two, the C18TMS resulted in more distinctly formed mesoporous silica layers with higher measured specific surface areas. Because the type of support material greatly influences the catalytic behaviour of the loaded catalysts, two different carbonization techniques were explored; namely the bubbling method using toluene as a carbon source, and a nanocasting method where resorcinol formaldehyde (RF) was the carbon source. The toluene-synthesized hollow carbon spheres had advantages over their RF-synthesized counterparts in that they were more thermally stable and had a more graphitic crystalline carbon framework. The RF-synthesized carbon, however, possessed a pseudo-capacitance due to surface carbon-oxygen groups, as well as a higher specific surface area, which resulted in the RF-carbon cyclic voltammetry profile spanning a larger current range in microampere per square centimetre. The effect of the size of the support materials was also explored; comparing 350 nm and 150 nm hollow carbon spheres. Besides the type of carbon, the metal precursor used to synthesize the catalyst nanoparticles was also explored, with either platinum(II)chloride (PtCl2) or platinum(II)acetylacetonate [Pt(acac)2] being used as the platinum source. It is also known that achieving high metal yields using conventional methods is quite difficult, and so an easier, quicker and less wasteful method was also explored; comparing the traditional wet-impregnation (WI) method with a chemical vapour deposition (CVD) method. Ultimately, it was found that platinum loaded on top of small-sized toluene-synthesized hollow carbon spheres using the CVD method and Pt(acac)2 as the metal precursor was the better catalyst in terms of oxygen reduction (determined using linear sweep voltammetry measurements); outperforming even commercial Pt/C catalysts as a result of improved mass transfer afforded by the voided cores of the hollow carbon spheres. The ability of a catalyst to withstand the reaction conditions present in a PEM fuel cell (i.e. oxygen-rich environments) was also considered. The stability of the catalysts was tested using chronoamperometry measurements in an oxygen-saturated perchloric acid solution. It was evident that the platinum loaded on the inner shells of the hollow carbon spheres showed far superior stability to those loaded on the outside surface. This was attributed to the qualities bestowed by the carbon shell around the platinum nanoparticles, protecting said platinum against the consequences of support corrosion due to the oxygenated environment; consequences such as metal sintering and interaction with surrounding carbon supports for example. These encapsulated catalysts, however, displayed a decrease in electrocatalytic activity compared to the catalysts with top-loaded platinum. In conclusion, the study of different platinum-carbon catalysts studied in the current work revealed that (a) loading platinum on top of small sized toluene-synthesized hollow carbon spheres using a CVD method and Pt(acac)2 as a metal precursor resulted in a highly active oxygen reduction catalyst, while (b) loading platinum on the inside surface of the hollow carbon spheres under the dame conditions resulted in a more electrocatalytically stable catalyst. / LG2017

Li, Li = 多功能介孔微米球 / 李麗. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 97-111). / Abstracts in English and Chinese. / Li, Li = Duo gong neng jie kong wei mi qiu / Li Li. / Abstract --- p.i / 摘要 --- p.iii / Acknowledgement --- p.v / Table of Contents --- p.vii / List of Figures --- p.x / Chapter 1 --- Introduction / Chapter 1.1 --- Multifunctional microspheres --- p.1 / Chapter 1.1.1 --- Preparations --- p.3 / Chapter 1.1.2 --- Applications --- p.8 / Chapter 1.2 --- Photophysical properties of rare earth ions --- p.13 / Chapter 1.3 --- Outline of thesis --- p.20 / Chapter 2 --- Preparation of Mesostructured Microspheres by Spray Pyrolysis / Chapter 2.1 --- Nanomaterials prepared by spray pyrolysis --- p.22 / Chapter 2.2 --- Our spray pyrolysis system --- p.29 / Chapter 3 --- Luminescent Mesostructured Titania Microspheres / Chapter 3.1 --- Rare earth-doped titania nanomaterials --- p.32 / Chapter 3.2 --- Experimental --- p.34 / Chapter 3.3 --- Results and discussion --- p.35 / Chapter 3.3.1 --- As-prepared undoped mesostructured titania microspheres --- p.35 / Chapter 3.3.2 --- Thermally-treated undoped mesostructured titania microspheres / Chapter 3.3.3 --- Rare earth-doped nanocrystalline titania microspheres --- p.43 / Chapter 3.3.4 --- Nanocrystalline titania microspheres co-doped with europium and samarium --- p.54 / Chapter 3.4 --- Conclusion --- p.55 / Chapter 4 --- Luminescent Mesostructured Silica Microspheres / Chapter 4.1 --- Rare earth complex-doped mesostructured silica matrices --- p.57 / Chapter 4.2 --- Experimental --- p.61 / Chapter 4.3 --- Results and discussion --- p.62 / Chapter 4.3.1 --- Rare earth complex-doped mesostructured silica microspheres --- p.62 / Chapter 4.3.2 --- Rare earth-doped mesostructured silica microspheres --- p.70 / Chapter 4.4 --- Conclusion --- p.72 / Chapter 5 --- Magnetic Luminescent Mesostructured Silica Microspheres / Chapter 5.1 --- Multifunctional microspheres containing magnetic components --- p.73 / Chapter 5.2 --- Experimental --- p.74 / Chapter 5.3 --- Results and discussion --- p.76 / Chapter 5.3.1 --- Magnetic mesostructured silica microspheres --- p.76 / Chapter 5.3.2 --- Magnetic luminescent mesostructured silica microspheres --- p.80 / Chapter 5.4 --- Conclusion --- p.83 / Chapter 6 --- Magnetic Photosensitive Mesostructured Silica Microspheres / Chapter 6.1 --- Mesostructured composite materials for optical applications --- p.84 / Chapter 6.2 --- Experimental --- p.87 / Chapter 6.3 --- Results and discussion --- p.89 / Chapter 6.3.1 --- Photosensitive mesostructured silica microspheres --- p.89 / Chapter 6.3.2 --- Magnetic photosensitive mesostructured silica microspheres --- p.91 / Chapter 6.4 --- Conclusion --- p.92 / Chapter 7 --- Summary --- p.94 / References --- p.97

Thesis (Ph.D.)--Kent State University, 2008. / Title from PDF t.p. (viewed May 28, 2009). Advisor: Mietek Jaroniec. Keywords: mesoporous carbons, inverse replication, hard templating, OMC, CMK-3, CMK-5, mesoporous silicas, OMS, SBA-15, MCM-48, KIT-6, colloids, colloidal crystal, nanomaterials, gas adsorption. Includes bibliographical references (p. 184-194).

Thesis (Ph.D.) - University of St Andrews, March 2009. / Restricted until 31st March 2010.

Thesis (Ph.D.) - University of St Andrews, June 2009. / Restricted until 5th June 2011.

貴金屬納米顆粒催化劑因其獨特的性質而備受關注。他們的高比表面積和可控的形貌使得他們表現出於同類體相材料所不同的催化性能。為了避免催化反應過程中由於納米顆粒本身形貌的改變而引起的催化活性降低，貴金屬納米顆粒通常被負載在固體氧化物載體上。同時，由於協同作用的產生，固體金屬氧化物載體在反應過程中也能對納米顆粒的催化效果產生影響。本論文系統介紹了利用超聲噴霧法製備貴金屬納米顆粒負載的金屬氧化物微納米球的過程，以及為研究這種微纳米球的催化性能而進行的實驗檢測。氧化物存在不仅为催化剂提供了载体，而且其介孔结构亦有利于反应物扩散到纳米催化剂的周围，从而提高反应的速率。 / 本論文首先介紹了一步法製備貴金屬納米顆粒負載的金屬氧化物微纳米球及其在催化反应中的應用。我們選擇了金、鉑和鈀來分別負載在二氧化鈦、二氧化鋯和三氧化二鋁微納米球上。這幾種貴金屬和氧化物都是在環境污染控制、石油化工產業和醫藥產業中具有代表性的催化劑及襯底。除了檢測我們所製備的微納米顆粒的結構形貌等特徵外，我們還利用對硝基苯酚還原為對胺基苯酚的這個催化反應檢驗了這些貴金屬納米顆粒負載的氧化物微納米球的催化活性。考慮到三種貴金屬和三種氧化物的排列組合，以及金屬含量可能產生的影響，我們準備了九類共18份樣品，逐個進行催化反應。最後的結果顯示，含鈀0.1%摩爾比例的二氧化鈦表現出最強的催化活性。同时，這種方法也可以推廣到其他的貴金屬以及氧化物襯底，從而可以簡單方便地製備各种氧化物负载貴金屬催化劑，并可以對他們之間的協同作用進行研究。 / 此外，我根據同樣的超聲噴霧法製備了貴金屬負載的空心介孔氧化物微納米球。這個研究課題引入了聚苯乙烯球作為模板。同時利用聚苯乙烯球表面修飾過的金屬納米顆粒之间的相互作用，實現了金屬納米顆粒在球表面的吸附，进而聚苯乙烯球可以作為載體將金屬納米顆粒帶入介孔氧化物中。通過熱分解將聚苯乙烯球除去後，金屬納米顆粒就可以吸附在空心介孔氧化物球的內表面。在這個實驗中，我們先製備好據有特殊形貌的金屬納米顆粒，比如金納米棒、鈀納米立方体和金納米棒外面包覆鈀的納米殼鞘結構。然後借助聚苯乙烯球將其帶入介孔二氧化鈦和二氧化鋯及二氧化硅中。在對硝基苯酚還原的實驗中，这种介孔微纳米球表现出良好的催化性能并在一定程度上提高了催化剂的循环性。 / 为了尽可能的提高催化剂的循环性，我希望能獲得據有良好磁性的介孔微納米球。我們嘗試了兩種方法，一是將磁性納米顆粒比如鐵的氧化物納米顆粒引入介孔氧化物微納米球，另一種方法是製備據有磁性的介孔氧化鐵微納米球。我们相信通過這種方法，貴金屬納米顆粒負載的介孔氧化物微納米球的催化性能，尤其是循環性能必然會顯著的提高。 / Noble metal nanoparticles/nanocrystals have attracted much attention as catalysts due to their unique characteristics, including high surface areas and well-controlled facets, which are not often possessed by their bulk counterparts. To avoid the loss of their catalytic activities brought about by their size and shape changes during catalytic reactions, noble metal nanoparticles/nanocrystals are usually dispersed and supported finely on solid oxide supports to prevent agglomeration, nanoparticle growth, and therefore the decrease in the total surface area. Moreover, metal oxide supports can also play important roles in catalytic reactions through the synergistic interactions with loaded metal nanoparticles/nanocrystals. In this thesis, I use ultrasonic aerosol spray to produce hybrid microspheres that are composed of noble metal nanoparticles/nanocrystals embedded in mesoporous metal oxide matrices. The mesoporous metal oxide structure allows for the fast diffusion of reactants and products as well as confining and supporting noble metal nanoparticles. / I will first describe my studies on noble metal-loaded mesoporous oxide microspheres as catalysts. Three types of noble metals (Au, Pt, Pd) and three types of metal oxide substrates (TiO₂, ZrO₂, Al₂O₃) were selected, because they are widely used for practical catalytic applications involved in environmental cleaning, pollution control, petrochemical, and pharmaceutical syntheses. By considering every possible combination of the noble metals and oxide substrates, nine types of catalyst samples were produced. I characterized the structures of these catalysts, including their sizes, morphologies, crystallinity, and porosities, and their catalytic performances by using a representative reduction reaction from nitrobenzene to aminobenzene. Comparison of the catalytic results reveals the effects of the different noble metals, their incorporation amounts, and oxide substrates on the catalytic abilities. For this particular reaction, I found that Pd nanoparticles supported on mesoporous TiO₂ exhibit the best catalytic performance. The demonstrated low-cost and high-productivity preparation method can be extended to other catalysts, which can contain various metals and oxide substrates and will have high potential for industrial applications. Our preparation method also provides a platform for the studies of the synergetic catalytic effects between different oxide substrates and metals. / I further fabricated hollow mesoporous microspheres containing differently shaped noble metal nanocrystals. Hollow structures are strongly desired in many applications because of their high pore volumes, surface areas, and possible light-trapping effect. In my study, the hollow structures were obtained by simply dispersing polystyrene (PS) nanospheres into the precursor solution for aerosol spray. The PS spheres were removed by thermal calcination to produce hollow mesoporous microspheres. In my first study, the noble metal salts were dissolved in the precursor solutions, and the noble metal nanoparticles were obtained through thermal calcination. In this way, the size and shape of the metal nanoparticles cannot be well controlled. In my second study, I first grew noble metal nanocrystals and then incorporated them into the oxide supports. This preparation route allowed me to incorporate metal nanocrystals with controlled sizes, shapes, and compositions into the oxide matrices. The metal nanocrystals I used in this experiment included Pd nanocubes, Au nanorods, and Au corePd shell nanorods. These nanocrystals were functionalized with thiol-terminated methoxypoly(ethylene glycol) . The surface functionalization allowed them to adsorb on the PS spheres. After thermal calcination, the noble metal nanocrystals were left inside and adsorbed on the inner surface of the hollow mesoporous metal oxide microspheres. I investigated the catalytic activities of the Pd nanocube-embedded hollow mesoporous TiO₂ and ZrO₂ microspheres for the reduction of 4-nitrophenol to 4-aminophenol. I also examined the recyclability of the Pd nanocube-embedded hollow mesoporous ZrO₂ microsphere catalysts. The results showed that the combination of the noble metal nanocrystals and oxides prevents the aggregation of the nanostructures and reduces the loss of the catalysts during the recycling processes, leading to the remarkable recyclability of the hybrid catalyst. This method for the preparation of noble metal nanostructure-embedded hollow mesoporous oxide microspheres can greatly facilitate the investigation on the catalytic properties of noble metal nanocrystal and metal oxide hybrid nanostructures and therefore guide the design and fabrication of high-performance catalysts. / Last but not least, I investigated the magnetic mesoporous microspheres to enable a better recyclability of the mesoporous oxide catalysts. Both magnetic nanoparticle-included mesoporous metal oxides and mesoporous magnetic oxides were presented. The successfully syntheses of these microspheres will greatly improve the catalytic performance of the noble metal nanoparticle-loaded mesoporous oxide microspheres. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Jin, Zhao = 貴金屬納米顆粒負載的介孔金屬氧化物微納米球及其催化應用 / 金釗. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Jin, Zhao = Gui jin shu na mi ke li fu zai de jie kong jin shu yang hua wu wei na mi qiu ji qi cui hua ying yong / Jin Zhao. / Abstract --- p.i / 摘要 --- p.iii / Acknowledgement --- p.v / Table of Contents --- p.vii / List of Figures --- p.x / List of Tables --- p.xvii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Mesoporous metal oxide materials --- p.1 / Chapter 1.1.1 --- Overview on mesoporous materials --- p.1 / Chapter 1.1.2 --- Syntheses of mesoporous metal oxides --- p.3 / Chapter 1.1.2.1 --- Preparation of mesoporous metal oxides through soft-templating methods --- p.3 / Chapter 1.1.2.2 --- Preparation of mesoporous metal oxides through hard-templating methods --- p.8 / Chapter 1.1.3 --- Applications of mesoporous metal oxides --- p.11 / Chapter 1.1.3.1 --- Catalysis --- p.12 / Chapter 1.1.3.2 --- Energy conversion and storage --- p.13 / Chapter 1.1.3.3 --- Sensing --- p.13 / Chapter 1.2 --- Noble metal nanopartilces --- p.15 / Chapter 1.2.1 --- Overview of noble metal nanoparticles --- p.15 / Chapter 1.2.2 --- Catalytic applications of noble metal nanoparticles --- p.19 / Chapter 1.2.2.1 --- Automotive converter --- p.19 / Chapter 1.2.2.2 --- Suzuki cross-coupling reaction --- p.20 / Chapter 1.3 --- The overview of this thesis --- p.22 / References --- p.24 / Chapter 2 --- Ultrasonic Aerosol Spray --- p.30 / Chapter 2.1 --- Working principle and our ultrasonic aerosol spray system --- p.30 / Chapter 2.2 --- Materials synthesized by the AASA method --- p.34 / References --- p.37 / Chapter 3 --- Materials Characterization Methods and Catalytic Studies --- p.39 / Chapter 3.1 --- Characterization methods --- p.39 / Chapter 3.2 --- Model catalytic reaction --- p.41 / References --- p.45 / Chapter 4 --- Noble Metal Nanoparticle-Loaded Mesoporous Oxide Microspheres --- p.46 / Chapter 4.1 --- Experiments --- p.48 / Chapter 4.2 --- Results and discussion --- p.50 / Chapter 4.2.1 --- Mesoporous metal oxide microspheres --- p.50 / Chapter 4.2.2 --- Noble metal nanoparticle-loaded mesoporous oxide microspheres --- p.55 / Chapter 4.3 --- Summary --- p.73 / References --- p.75 / Chapter 5 --- Metal Nanostructure-Embedded Hollow Mesoporous Oxide Microspheres Prepared with Polystyrene Nanospheres as Carriers and Templates --- p.78 / Chapter 5.1 --- Experiments --- p.83 / Chapter 5.2 --- Results and discussion --- p.88 / Chapter 5.2.1 --- Hollow mesoporous oxide microspheres prepared with the PS spheres as templates --- p.88 / Chapter 5.2.2 --- Noble metal nanostructure-embedded hollow mesoporous oxide microspheres --- p.90 / Chapter 5.3 --- Summary --- p.106 / References --- p.108 / Chapter 6 --- Magnetic Mesoporous Microspheres --- p.113 / Chapter 6.1 --- Experiment --- p.115 / Chapter 6.2 --- Results and discussion --- p.117 / Chapter 6.2.1 --- Magnetic nanoparticle-included mesoporous TiO₂ microspheres --- p.117 / Chapter 6.2.2 --- Mesoporous iron oxide microspheres --- p.125 / Chapter 6.3 --- Summary --- p.128 / References --- p.130 / Chapter 7 --- Conclusions --- p.131

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.

Thesis (Ph. D.)--Michigan State University. Dept. of Chemistry, 2006. / Title from PDF t.p. (viewed on Apr. 16, 2009) Includes bibliographical references. Also issued in print.

Thesis (Ph.D.)--Drexel University, 2009. / Includes abstract and vita. Includes bibliographical references (leaves 462-468).