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Vật liệu MOFs
NANOSCALE METALORGANIC FRAMEWORKS: SYNTHESIS AND APPLICATION OF BIMODAL MICRO/MESO-STRUCTURE AND NANOCRYSTALS WITH CONTROLLED SIZE AND SHAPE Thèse MINH-HAO PHAM Doctorat en génie chimique Philosophiae Doctor (Ph.D.) Québec, Canada © Minh-Hao Pham, 2013 iii Résumé Les composés à réseau moléculaire organométalliques (MOFs) ont émergé comme de nouvelles classes de matériaux hybrides organo-inorganiques avec des potentialités significatives en séparation, stockage de gaz, catalyse et support de médicaments. Ces lliques sont 2 g 1 et des volumes de pores supérieurs à 4.3 cm 3 g 1 . Dans cette thèse trois différentes approches ont été développées pour la synthèse des nanocristaux MOFs à deux modes micro-mésoporeux, ainsi que des nanocristaux MOFs à taille et forme contrôlable. En plus, ces nanocristaux MOFs ont été utilisé comme un agent structurant pour la synthèse de nanocomposite hybride platine-oxyde de titane (metal-oxideTiO 2 PtO x ) qui ont été utilisé visible. Dans ce travail: (i) La première approche implique une méthode utilisant un surfactant, suivi de traitement solvo-thermale en présence nanocristaux MOFs micro- -ionique tell que F127 (EO 97 PO 69 EO 97 ) pour induire une structure mésoporeuse provoque labilité de la cristallisation du mur des pores de la structure MOF. acétique contrôle la vitesse de cristallisation du réseau MOFs pour former une des nanocristaux de [Cu 3 (BTC) 2 ] et [Cu 2 (HBTB) 2 ] de structure mésoporeuse avec des diamètres de pores autour de 4.0 nm et des micropores intrinsèques ont été synthétisés. (ii) La méthodologie de modulation de la coordination a été développée pour contrôler la forme et la taille des nanocristaux MOFs. Des nanocubes et nanofeuilles de [Cu 2 (ndc) 2 (dabco)] n pyridine ou la pyridine uniquement, respectivement comme modulateurs sélectifs. Ces nanocristaux MOFs possèdent une cr 2 . (iii) La synthèse hydrothermale en contrôlant la taille de nanocristaux de carboxylates de structure iv MOFs, en utilisant simultanément des réactifs stabilisants et des réactifs contrôlant la déprotonation a été démontrée. Dans le cas de FeMIL-88BNH 2 , la molécule triblock copolymer a été utilisée comme un réactif stabilisant en coordonnant avec le métal et contrôlant la un agent déprotonant des liants carboxyliques en variant sa concentration dans le milieu réactionnel, ainsi il régule la vitesse de nucléation, conduisant à aussi contrôler la taille ainsi que le rapport longueur/largeur des nanocristaux. (iv) Finalement, des nanocomposites hybrides Fe 2 O 3 TiO 2 PtO x performante ont été développés en utilisant des nanocristaux FeMIL-88B composés de centres Fe 3 ( 3 O) liés par coordination insaturée comme template solide. Ce type de nanocomposites non seulement absorbe la lumière visible mais aussi améliore la séparation des électrons et des trous photo-les deux co- catalyseurs (Fe 2 O 3 and PtO x ) localisés sur deux opposites surfaces du creux. En conséquence, l'efficacité en photocatalyse de ce type de nanocomposites est élevée pour la production d'H 2 à partir de l'eau sous la lumière visible. v Abstract Metalorganic frameworks (MOFs) have emerged as an important new class of porous inorganicorganic hybrid solids with the potential for a significant impact on separation, gas storage, catalysis and biomedicine. These materials are formed by assembly process in which metal ions are linked together by rigid organic ligands, which creates enormous surface areas (up to 6500 m 2 g 1 ) and high pore volumes (up to 4.3 cm 3 g 1 ). In this thesis, three different synthetic approaches have been developed to achieve bimodal micro/mesoporous MOF nanocrystals as well as nanosized MOFs with controlled size and shape. In addition, using the synthesized MOF nanocrystals as templates, a new hollow hybrid metal-oxideTiO 2 PtO x nanocomposite has also been prepared, and used as the visible-light driven photocatalyst for the hydrogen production from water. In this work, (i) the first approach involves nonionic surfactant-templated solvothermal synthesis in the presence of acetic acid toward hierarchically micro-mesoporous MOF nanocrystals. The use of a nonionic surfactant such as F127 (EO 97 PO 69 EO 97 ) as mesostructure template induces the ability to crystallize a MOF structure of pore wall, while the presence of acetic acid allows control of the crystallization rate of the framework to form well-defined mesostructures within the crystalline MOF nanocrystals. Using this approach, [Cu 3 (BTC) 2 ] and [Cu 2 (HBTB) 2 ]-based MOF nanocrystals containing mesopores with diameter around 4.0 nm and intrinsic micropores have been successfully synthesized. (ii) Secondly, the coordination modulation methodology has been developed to control shape and size of MOF crystals at the nanoscale. Nanocubes and nanosheets of [Cu 2 (ndc) 2 (dabco)] n MOF have been rationally synthesized by using simultaneously acetic acid and pyridine or only pyridine, respectively, as selective modulators. These MOF nanocrystals exhibit high crystallinity and high CO 2 sorption capacity. Their morphology- dependent CO 2 sorption property has also been demonstrated. (iii) Thirdly, the size- controlled hydrothermal synthesis of uniform carboxylate-based MOF nanocrystals using simultaneously stabilizing reagent and deprotonation-controlled reagent has been demonstrated. In case of FeMIL-88BNH 2 , the molecular triblock copolymers as stabilizing reagents coordinate with the metal ions and thus stabilize nuclei, which suppress vi the crystal growth to form nanocrystals. Acetic acid as deprotonation-controlled reagent adjusts the deprotonation of the carboxylic linker via varying its concentration in the reaction mixture, and thus regulates the rate of nucleation, leading to tailoring the size and aspect ratio (length/width) of the nanocrystals. (iv) Finally, a new hollow hybrid metal- oxideTiO 2 PtO x nanocomposite as an efficient photocatalyst has been developed by using iron-based MIL-88B nanocrystals consisting of coordinatively unsaturated Fe 3 3 O) clusters as template. The hollow nanocomposite not only absorbs visible light, but also enhances the separation between photogenerated electrons and holes because of its thin wall and the surface separation of two distinct functional cocatalysts (Fe 2 O 3 and PtO x ) on two different surface sides of the hollow. As a result, the efficient photoactivity of the nanocomposite photocatalysts has been found for the H 2 production from water under visible light irradiation. vii Table of Contents Résumé iii Abstract v Abbreviations ix Acknowledgements xi Preface xiii Chapter 1 Introduction 1 1.1 General introduction 1 1.2 Objectives of the thesis 2 1.3 References 3 Chapter 2 Literature Review 5 2.1 Metalorganic frameworks 5 2.2 Mesoporous metal-organic frameworks 13 2.2.1 MOFs with mesocages 13 2.2.2 MOFs with mesochannels 21 2.2.3 Mesoporous MOFs from supramolecular templates 26 2.2.4 Prospective applications of MOFs involving mesopores 30 2.3 Nanosized metal-organic frameworks 33 2.3.1 Coordination modulation 34 2.3.2 Stabilizing reagent 36 2.3.3 Microemulsion 38 2.3.4 Synthetic parameters 41 2.3.5 Top-down approach 44 2.3.6 Potential application of MOFs involving nanosize 45 2.4 Photocatalytic water splitting 51 2.5 References 54 Chapter 3 Characterizations 65 3.1 Introduction 65 3.2 X-ray diffraction 65 3.3 Electron microscopy 67 3.4 X-ray photoelectron spectroscopy 69 3.5 Fourier transform infrared spectroscopy 71 3.6 Ultraviolet-visible spectroscopy 72 3.7 -Potential analysis 73 3.8 Thermal analysis 74 3.9 Elemental analysis 75 3.10 Gas sorption 76 3.10.1 Physisorption isotherm and surface area measurement. 76 viii 3.10.2 Micropore analysis 78 3.10.3 Size distribution of mesopores 80 3.11 Gas chromatography analysis 81 3.12 References 81 Chapter 4 Route to Bimodal MicroMesoporous MOF Nanocrystals 83 4.1 Introduction 89 4.2 Experimental 90 4.3 Results and discussion 91 4.4 Conclusions 100 4.5 Appendix 101 4.6 References 104 Chapter 5 Rational Synthesis of MOF Nanocubes and Nanosheets Using Selective Modulators and Their Morphology-Dependent Gas-Sorption Properties 107 5.1 Introduction 113 5.2 Experimental 115 5.3 Results and discussion 117 5.4 Conclusions 123 5.5 Appendix 123 5.6 References 126 Chapter 6 Novel Route to Size-Controlled FeMIL-88BNH 2 MOF Nanocrystals 129 6.1 Introduction 135 6.2 Experimental 137 6.3 Results and discussion 139 6.4 Conclusions 150 6.5 Appendix 151 6.6 References 152 Chapter 7 Hollow Fe 2 O 3 TiO 2 –PtO x Nanostructure with Two Distinct Cocatalysts Embedded Separately on Two Surface Sides for Efficient Visible Light Water Splitting to Hydrogen 157 7.1 Introduction 163 7.2 Results and discussion 166 7.3 Conclusions 172 7.4 Experimental 172 7.5 Appendix 175 7.6 References 179 Chapter 8 Conclusions and Prospects 181 8.1 General conclusions 181 8.2 Prospects 182 List of Publications 185 ix Abbreviations AAS Atomic absorption spectroscopy BDC 1,4-benzenedicarboxylic acid BET BrunauerEmmettTeller BJH BarrettJoynerHalenda BPDC -biphenyldicarboxylic acid BPY -bipyridine BTB 1,3,5-tris[4-carboxyphenyl]benzene BTC 1,3,5-benzenetricarboxylic acid BTE -(benzene-1,3,5-triyl-tris(ethyne-2,1-diyl))tribenzoate BTTC Benzo-(1,2;3,4;5,6)-tris(thiophene--carboxylate) CB Conduction band cbIM 5-chlorobenzimidazole CTAB Cetyltrimethylammonium bromide DABCO 1,4-diaza-bicyclo[2.2.2]octane DBA 4-(dodecyloxy)benzoic acid DMF N,N-dimethylformamide DOT 2,5-dioxidoterephthalate EDS Energy dispersive X-ray spectroscopy FTIR Fourier transform infrared spectroscopy GC Gas chromatography H 6 L 1,3,5---biphenyl]-4-yl)benzene IUPAC International Union of Pure and Applied Chemistry x MOF Metalorganic framework MTN Mobil thirty-nine NDC 1,4-naphthalenedicarboxylic acid 2,6-NDC 2,6-naphthalenedicarboxylic acid N-EtFOSA N-ethyl peruorooctylsulfonamide NHE Normal hydrogen electrode PCP Porous coordination polymer PTEI 5,5'-((5'-(4-((3,5-dicarboxyphenyl)ethynyl)phenyl)-[1,1':3',1''-terphenyl]-4,4''- diyl)-bis(ethyne-2,1-diyl))diisophthalate SAXS Small angle X-ray scattering SBU Secondary building unit SDC 4,4'-stilbenedicarboxylic acid SEM Scanning electron microscopy ST Super tetrahedron TATAB -s-triazine-1,3,5-triyltri-p-aminobenzoate TATB -s-trizaine-2,4,6-triyltribenzoic TCPP Tetrakis(4-carboxyphenyl)porphyrin TEM Transmission electron microscopy T 2 DC Thieno[3,2-b]thiophene-2,5-dicarboxylate TTEI 5,5',5''-(((benzene-1,3,5-triyltris(ethyne-2,1-diyl))tris(benzene-4,1-diyl))tris- (ethyne-2,1-diyl))triisophthalate UV-vis Ultraviolet-visible spectroscopy VB Valence band XPS X-ray photoelectron spectroscopy XRD X-ray diffraction [...]... nanoscale MOFs with desired shape and size 1.2 Objectives of the thesis The aim of this thesis is to develop synthetic methods for preparing bimodal micro- and meso-porous MOF nanocrystals, uniform nanosized MOFs with controlled- shape and size and subsequently, the extensive application of the prepared nanosized MOFs The first objective is nonionic surfactant-templated solvothermal method in the presence of. .. Stabilizing- and capping-reagents have been employed to suppress the crystal growth of MOFs which lead to nanosized MOFs.35 But in general, it is difficult to control the shape and size of MOF nanoparticles and the resulted nanoparticles usually appear as aggregation rather than individual nanocrystals. 36 Up to date, there is a great challenge to the preparation of mesoporous MOF nanocrystals and uniform nanoscale. .. features of representative mesoporous MOFs Mesoporous structure (Å) MOFs Linkers Apertures (Å) Cages Channels Ref Templates MIL-101 BDC 29 and 34 12.0 and 14.7 64 MIL-101_NDC 2,6-NDC 39 and 46 13.5 and 18.2 114 MIL-100 BTC 25 and 29 4.8 and 8.6 26 Tb-mesoMOF TATB 39 and 47 13.0 and 17.0 115 UMCM-2 T2DC and BTB 26 32 116 DUT-6/MOF-205 NDC and BTB 2530 117, 66 MOF-210 BTE and BPDC 26.9 48.3 66 PCN-53 BTTC... performance of MOFs, several strategies to enlarge their pore size toward the mesopore regime (pore size of 250 nm)24,25 and to downsize their crystal size to the nanometer scale have thus emerged.26 The mesopores and nanosizes promote the diffusion of guest molecules through MOFs and increase accessible active sites.27 Furthermore, the mesopores also allow complex substances to be encapsulated within MOF... deprotonation-controlling reagent for the preparation of uniform nanosized carboxylatebased MOFs with desired crystal sizes The control of the stabilizing reagent and deprotonation-controlling reagent over the size of the nanosized MOFs has been demonstrated Finally, after the successful synthesis, the extensive application of the nanosized MOFs to preparing a new hollow hybrid nanocomposite as an efficient... of conventional mesoporous materials 2.2.1 MOFs with mesocages A number of MOFs having large cavities within the range of 2 50 nm (so-called mesocages) have been prepared from one type of organic linker or the mixture of different linkers in coordination with metal-containing SBUs that possess different geometric shapes One of these MOF structures is MIL-101.64 The structure of MIL-101 consists of. .. size of < 2 nm) with large crystal sizes in the micrometer scale The small apertures of the micropores and the large crystal sizes of MOFs significantly limit extensive applications of MOFs, especially in the participation of large substances such as enzymes or in applications requiring nanoscale sizes such as drug delivery.22,23 Moreover, the long micropores within MOF microcrystals also induce diffusion... morphology of MOF nanocrystals The effects of the nature and the concentration of selective modulators on the shape and size of MOF nanocrystals have been demonstrated In addition, the morphology-dependent CO2 sorption property has also been illustrated The third objective is hydrothermal approach using simultaneously stabilizing reagent and deprotonation-controlling reagent for the preparation of uniform... field,14 and biomedicine.15 The prospective applications of MOFs are accounted for their stable framework,16 high porosity with enormous surface area and pore volume,17,18 the ability to systematically vary and functionalize their pore structure,19,20 and to rationally achieve pre-determined topologies with desired properties.21 Most of MOFs are microporous materials (pore size of < 2 nm) with large... largest mesocage with a dimension of 26.9 48.3 Å in MOF-210 consists of eighteen Zn4O(COO)6 SBUs, fourteen BTE and six BPDC linkers The material exhibits an enormous BET surface area of 6240 m2g-1 and a total carbon dioxide storage capacity of 2870 mg.g-1 BPDC BTE MOF-210 Figure 2.11 Structure of MOF-210 The yellow and orange spheres indicate spaces in the cages Reproduced with the permission of Science.66 . preparing bimodal micro- and meso-porous MOF nanocrystals, uniform nanosized MOFs with controlled- shape and size and subsequently, the extensive application of the prepared nanosized MOFs. The. NANOSCALE METALORGANIC FRAMEWORKS: SYNTHESIS AND APPLICATION OF BIMODAL MICRO/MESO-STRUCTURE AND NANOCRYSTALS WITH CONTROLLED SIZE AND SHAPE Thèse MINH-HAO PHAM. been developed to achieve bimodal micro/mesoporous MOF nanocrystals as well as nanosized MOFs with controlled size and shape. In addition, using the synthesized MOF nanocrystals as templates,