Mesostructured Crystalline Ceria with a Bimodal Pore System Using Block Copolymers and Ionic Liquids as Rational Templates

Brezesinski, Torsten; Erpen, Christian; Iimura, Ken–ichi; Smarsly, Bernd M.

doi:10.1021/cm0479180

Cited by 125 publications

(94 citation statements)

References 35 publications

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“…2E). In this case, the CeO 2 sublayer is composed of a uniaxially oriented bcc structure, [15] whereas the TiO 2 overlayer features an fcc lattice of mesopores, consistent with the TiO 2 /CeO 2 system described above. By contrast, two TiO 2 or CeO 2 films on top of each other do not www.advmat.de show any long-range orientation effect.…”

supporting

confidence: 77%

“…By contrast, the hexagonal pattern has to be assigned to the CeO 2 overlayer with well-ordered face-centered-cubic (fcc) mesostructure in [111] orientation. [15] The presence of diffraction spots in this scattering geometry demonstrates the presence of a uniform biaxial mesopore orientation. The full width at half maximum (FWHM) of these reflections is ca.…”

mentioning

confidence: 77%

“…Once the solution was homogeneous, KLE (100 mg) dissolved in ethanol (2.5 mL) and water (0.5 mL) was added. For ceria an adaptation of the preparation by Smarsly and coworkers was used [15]. Cerium(III) chloride heptahydrate (600 mg) was dissolved in ethanol (4 mL).…”

Section: Methodsmentioning

confidence: 99%

“…We find that the two networks crystallize separately and, unlike TiO 2 , CeO 2 features a gradual crystal growth. [14,15] Based on the line broadening of the (101) reflection of anatase and the (111) reflection of cerianite, an average nanocrystal size of 15-16 nm and 6-7 nm, respectively, is obtained after calcination at 700°C. These films can be considered 100 % crystalline.…”

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confidence: 99%

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Self‐Assembled Metal Oxide Bilayer Films with “Single‐Crystalline” Overlayer Mesopore Structure

2007

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The preparation of metal oxide films with nanometer-scale periodicity and solid-state functionality by sol-gel processing has attracted significant attention in recent years because of the promise of the resulting systems for materials science and the ease of the underlying templating processes. Using evaporation-induced self-assembly (EISA), [1] crack-free mesoporous coatings of various metal oxides can be generated with good reproducibility, especially based on the utilization of appropriate structure-directing agents, such as block copolymers of the "KLE" or "PIB-PEO" type (KLE = poly(ethylene-cobutylene)-block-poly(ethylene oxide), PIB-PEO = polyisobutylene-block-poly(ethylene oxide)).[2] Meanwhile, the deposition procedures allow fine-tuning of structural parameters such as pore size and shape, film thickness, and degree of crystallinity. [3] Owing to the strong interaction with the substrate, the primary lyotropic phase used as the structure-directing template and the final mesopore architecture adopt a strongly preferred orientation relative to the substrate plane, normally exposing the layers with the highest structural packing density.[4] These self-assembled materials are composed of relatively small mesostructured domains that are randomly oriented with respect to one another. In other words, the pore architectures possess only uniaxial orientation.[5] Nevertheless, several fields of application, for example, electronics or optics, would benefit greatly from a uniform biaxial mesopore alignment. Such films with iso-oriented domains corresponding to a periodically ordered array (at the best on the scale of several centimeters) without grain/domain boundaries could be regarded as mesophase single crystals. However, up until now EISA has lacked control over the macroscopic distribution of mesopores, and only a few strategies have been presented to bypass this serious drawback.Miyata et al. reported the successful preparation of continuous mesoporous silica films with fully aligned mesochannels on substrates coated with a rubbed polyimide (a well-known procedure in liquid crystal (LC) technology).[6] Micelle/pore alignment during self-assembly is achieved through the interaction of the hydrophobic surfactant tails with the chains of the rubbed polyimide layer. [7] In spite of the technical feasibility, this approach has some weak points, in particular the necessity of precoating substrates with a polymer layer and its subsequent patterning to obtain a surface-relief structure. This orientation layer is finally located between the substrate and the mesostructured material and can cause film delamination during annealing. Moreover, pore alignment can only be achieved for hexagonal silica material. Other approaches known from work on the orientation of block copolymer mesophases include nanostructured surface reliefs fabricated by using lithography, [8] solvent-induced microdomain orientation, [9] and casting from crystallizing solvents. [10] In all these cases, the free choice of substrate and material is,...

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supporting

confidence: 77%

mentioning

confidence: 77%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Self‐Assembled Metal Oxide Bilayer Films with “Single‐Crystalline” Overlayer Mesopore Structure

2007

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“…[279] Smarsly and co-workers fabricated mesoporous CeO 2 thin films with a crystalline framework and bimodal pore size distribution using a mixture of block copolymer KLE and ionic liquid [C 16 Mim] [Cl]. [293] This example demonstrates that the methodology used in the fabrication of hierarchical porous SiO 2 (Section 3.3) can also be extended to the fabrication of hierarchical porous metal oxides. More recently, Zhu and co-workers fabricated V 2 O 5 with hierarchical mesopores using a mixture of CTAB and [BMim] [Cl].…”

Section: Metal Oxidesmentioning

confidence: 99%

Preparation of Inorganic Materials Using Ionic Liquids

2009

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Conventional synthesis of inorganic materials relies heavily on water and organic solvents. Alternatively, the synthesis of inorganic materials using, or in the presence of, ionic liquids represents a burgeoning direction in materials chemistry. Use of ionic liquids in solvent extraction and organic catalysis has been extensively studied, but their use in inorganic synthesis has just begun. Ionic liquids are a family of non-conventional molten salts that can act as templates and precursors to inorganic materials, as well as solvents. They offer many advantages, such as negligible vapor pressures, wide liquidus ranges, good thermal stability, tunable solubility for both organic and inorganic molecules, and much synthetic flexibility. In this Review, the use of ionic liquids in the preparation of several categories of inorganic and hybrid materials (i.e., metal structures, non-metal elements, silicas, organosilicas, metal oxides, metal chalcogenides, metal salts, open-framework structures, ionic liquid-functionalized materials, and supported ionic liquids) is summarized. The status quo of the research field is assessed, and some future perspectives are furnished.

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Inorganic Nanomaterials Synthesis Using Ionic Liquids

Taubert

2005

Encyclopedia of Inorganic Chemistry

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Ionic liquids (ILs) have been studied for a wide range of applications, including organic synthesis, separation and extraction, and electrochemistry. Inorganic nanomaterials synthesis in and with ILs is still a new but rapidly developing research branch. This article gives an overview over recent developments in the field of inorganic materials synthesis in ILs. Furthermore, the article highlights a few promising approaches that add value to inorganic materials science by giving access to hitherto unknown inorganic materials or materials that have so far only been accessible with great experimental effort via more conventional processes.

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Mesostructured Crystalline Ceria with a Bimodal Pore System Using Block Copolymers and Ionic Liquids as Rational Templates

Cited by 125 publications

References 35 publications

Self‐Assembled Metal Oxide Bilayer Films with “Single‐Crystalline” Overlayer Mesopore Structure

Self‐Assembled Metal Oxide Bilayer Films with “Single‐Crystalline” Overlayer Mesopore Structure

Preparation of Inorganic Materials Using Ionic Liquids

Inorganic Nanomaterials Synthesis Using Ionic Liquids

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