A general approach to crystalline and monomodal pore size mesoporous materials

Poyraz, Altuğ S.; Kuo, Chung‐Hao; Biswas, Sourav; King’ondu, Cecil K.; Suib, Steven L.

doi:10.1038/ncomms3952

Cited by 230 publications

(306 citation statements)

References 34 publications

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“…For instance, Fan et al prepared multicomponent mesoporous metal oxides in a versatile sol-gel solution consisting of acetic acid 13 . Suib et al reported an inverse micelle synthesis system to prepare mesoporous metal oxides 14 . Mesoporous materials with diverse morphologies and tunable pore sizes have been prepared by controlling the synthesis conditions and the properties of the template molecules based on soft templating 15,16 .…”

Section: Introductionmentioning

confidence: 99%

A general ligand-assisted self-assembly approach to crystalline mesoporous metal oxides

et al. 2018

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Mesoporous transition metal oxides with high crystallinity and large pore volumes were successfully synthesized by a widely applicable ligand-assisted self-assembly approach. In this approach, a carboxyl-containing ligand is employed as a coordination agent to retard the hydrolysis and condensation rates of the precursors. The ligands interact with the PEO chains of P123 via hydrogen bonds, which cooperatively ensures the controllable co-assembly of template micelles and the metal source during solvent evaporation. The X-ray diffraction, transmission electron microscopy, and nitrogen sorption results show that the obtained mesoporous metal oxides are constructed from numerous highly crystalline nanoparticles and possess close-packed mesostructures with uniform pore size distributions. A series of mesoporous transition metal oxides (Co

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Section: Introductionmentioning

confidence: 99%

A general ligand-assisted self-assembly approach to crystalline mesoporous metal oxides

et al. 2018

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“…16,17,20 No small surfactant soft-templating method exists for the synthesis of mesoporous metal titanates in the literature. 16 Also note that the metal titanates form at high temperatures (250−350°C).…”

Section: ■ Introductionmentioning

confidence: 99%

Molten Salt Assisted Self Assembly (MASA): Synthesis of Mesoporous Metal Titanate (CoTiO₃, MnTiO₃, and Li₄Ti₅O₁₂) Thin Films and Monoliths

et al. 2014

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Mesoporous metal titanates are very important class of materials for clean energy applications, specifically transition metal titanates and lithium titanates. The molten salt assisted self-assembly (MASA) process offers a new synthetic route to produce mesoporous metal titanate thin films. The process is conducted as follows: first a clear solution that contains two solvents (namely the hydrated salt (Co(NO 3 ) 2 · 6H 2 O or Mn(NO 3 ) 2 ·6H 2 O, or LiNO 3 ·xH 2 O, and ethanol), two surfactants (cethyltrimethylammonium bromide, CTAB, and 10-lauryl ether, C 12 EO 10 ), an acid and titanium source (titanium tetrabutoxide, TTB) is prepared and then spin or spray coated over a substrate to form a thin or thick lyotropic liquid crystalline (LLC) film, respectively. Finally, the films are converted into transparent spongy mesoporous metal titanates by a fast calcination step. Three mesoporous metal titanates (namely, CoTiO 3 , MnTiO 3 , and Li 4 Ti 5 O 12 ) have been successfully synthesized and structurally/thermally characterized using microscopy, spectroscopy, diffraction, and thermal techniques. The mesoporous cobalt and manganese titanates are stable up to 500°C and collapse at around 550°C into nanocrystalline Co 3 O 4 − TiO 2 and Mn 2 O 3 −TiO 2 ; however, lithium titanate is stable up to 550°C and crystalline even at 350°C. The crystallinity and pore size of these titanates can be adjusted by simply controlling the annealing and/or calcination temperatures. ■ INTRODUCTIONThe melting point of metal salts can be reduced significantly in a confined space -known as the confinement effect -such that they may act as solvents in a self-assembly process.1 Organizing surfactants into lyotropic liquid crystalline (LLC) mesophases by using molten salts can be beneficial in the production of new materials for clean energy applications.2,3 Recently, we have demonstrated that the molten phase of salts can be used as a solvent in the synthesis of mesoporus metal oxide modified silica 2 as well as titania. 3 This process was introduced as molten salt assisted self-assembly (MASA).2,3 The MASA is a useful process in producing materials that are difficult to produce using known synthesis techniques, and it can be regarded as a new synthetic route. Two solvents and two surfactants are needed in this self-assembly process. The first solvent is volatile and is used to homogenize the mixture of the ingredients to produce a clear solution, 2,3 and the second solvent is a salt, which organizes the mixture into an LLC mesophase upon evaporation of the first one. 3 Simply, a clear solution of a mixture of all the ingredients (salt, surfactants, water (or ethanol), polymerizing agent) can be spin coated over a substrate to form a thin film. Further polymerization of the polymerizing component (silica or titania source) takes place in the self-assembled soft media. The MASA process allows for efficient and homogeneous contact between the polymerizing silica or titania and the salt ions. The spin coated fresh samples are usually ...

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“…The resulting aggregated nanoparticles exhibit tunable pore structures, excellent thermal stability, and easily accessible oxidation states which contribute to a wide range of organic catalytic transformations [1]. Among the variety of transition metal oxide systems, mesoporous manganese oxides have proven to be efficient catalysts in the oxidation of alcohols to carboxylic acids.…”

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Cross Sectional Analysis of Cation Doped Transition Metal Oxide Mesoporous Catalyst Materials

et al. 2017

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UCT (University of Connecticut) mesoporous transition metal oxide materials are synthesized using an inverse micelle soft template and unique NOx chemistry. The resulting aggregated nanoparticles exhibit tunable pore structures, excellent thermal stability, and easily accessible oxidation states which contribute to a wide range of organic catalytic transformations [1]. Among the variety of transition metal oxide systems, mesoporous manganese oxides have proven to be efficient catalysts in the oxidation of alcohols to carboxylic acids. In addition to organic catalysis, there is interest in using the various mesoporous metal oxides in other fields such as energy and advanced separations.Doping of UCT materials is still in its infancy. Cation promoted mesoporous manganese oxides show increased catalytic activity while maintaining the structural characterization of traditional UCT material. However, one system that has been studied extensively in catalytic reactions involves doping with Cs + ions [2]. The levels of dopants like Cs + can be very small, perhaps 1 in 100 metal ions. In addition there has been some doping with transition metal systems such as iron doped manganese, cobalt doped iron, nickel doped titanium, and similar systems. These materials have interesting magnetic properties. Very few details of the location of these dopant ions are available.Typically, catalyst morphology is examined using SEM and TEM techniques. A dilute solution drop onto carbon film copper grid sample preparation for TEM is adequate to analyze the electron transparent particles along the edges of the aggregate. FIB has been employed in many cases to analyze cross sections of nanoparticles. This is typically done by first immobilizing the particles in a matrix (epoxy, metal, etc.) or on a substrate in order to obtain an adequate lamella without the loss of material due to structural instability [3][4][5]. In this work, lamella preparation of a variety of doped UCT materials is performed using an FEI Helios Nanolab 460F1 FIB without the use of bulk matrix immobilization in order to determine if the centers of these aggregates reflect the morphology and pore structure confirmed along the edges. TEM-EDS (FEI Talos S/TEM) of these cross sectioned particles can also be utilized to verify even distribution of detectable dopant amounts in the center of the aggregate [6]. References:[1] A.

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A general approach to crystalline and monomodal pore size mesoporous materials

Cited by 230 publications

References 34 publications

A general ligand-assisted self-assembly approach to crystalline mesoporous metal oxides

A general ligand-assisted self-assembly approach to crystalline mesoporous metal oxides

Molten Salt Assisted Self Assembly (MASA): Synthesis of Mesoporous Metal Titanate (CoTiO₃, MnTiO₃, and Li₄Ti₅O₁₂) Thin Films and Monoliths

Cross Sectional Analysis of Cation Doped Transition Metal Oxide Mesoporous Catalyst Materials

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A general approach to crystalline and monomodal pore size mesoporous materials

Cited by 230 publications

References 34 publications

A general ligand-assisted self-assembly approach to crystalline mesoporous metal oxides

A general ligand-assisted self-assembly approach to crystalline mesoporous metal oxides

Molten Salt Assisted Self Assembly (MASA): Synthesis of Mesoporous Metal Titanate (CoTiO3, MnTiO3, and Li4Ti5O12) Thin Films and Monoliths

Cross Sectional Analysis of Cation Doped Transition Metal Oxide Mesoporous Catalyst Materials

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Molten Salt Assisted Self Assembly (MASA): Synthesis of Mesoporous Metal Titanate (CoTiO₃, MnTiO₃, and Li₄Ti₅O₁₂) Thin Films and Monoliths