Preparation of three-dimensional chromium oxide porous single crystals templated by SBA-15

Zhu, Kake; Yue, Bin; Zhou, Wuzong

doi:10.1039/b210065g

Cited by 182 publications

(152 citation statements)

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“…In our previous work, we found that the mesochannels of SBA-15 and KIT-6 were far from completely filled by metal precursors due to a large loss of Si-OH groups during the organic template removal process that involved a thermal calcination, 40,41 and this phenomenon has also been reported by other groups. 35,42,43 Other approaches such as using solvents and supercritical fluid extraction require long periods of operation (.24 h) and it is difficult to remove the organic template completely. 44 Tian et al proposed microwave irradiation as an effective technique for making organic templates such as Pluronic P123 quickly and with total removal of the onedimensional (1D) SBA-15 material with the greatest preservation of the original mesoporous structure and surface hydroxyl groups.…”

Section: Introductionmentioning

confidence: 99%

Facile preparation of 3D ordered mesoporous CuOx–CeO2 with notably enhanced efficiency for the low temperature oxidation of heteroatom-containing volatile organic compounds

Chen

et al. 2013

RSC Adv.

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SBA-16 silica with intact surface hydroxyl groups was quickly obtained (5 min) via a fast-microwaveassisted method, and further adopted as an efficient template for the synthesis of three-dimensional (3D) ordered mesoporous CuO x -CeO 2 catalysts (htpCCx) through a simple and reproducible host-guest interaction. XRD, XPS, H 2 -TPR, and Raman results reveal that many of the Cu 2+ ions in htpCCx are incorporated into the CeO 2 lattice, leading to the formation of a Cu x Ce 12x O 22d solid solution, which produces a large number of oxygen vacancies and enhances the reducibility of the metal. The interaction of Cu and Ce is essential to the reaction as it maintains the Cu 2+ /Cu 1+ and Ce 4+ /Ce 3+ redox couples. The catalyst has a 3D mesostructure and possesses remarkably enhanced low-temperature activity for the combustion of epichlorohydrin. HtpCC20 has been identified as the most powerful catalyst for this reaction, with the reaction rate at 165 uC being about 6.3 and 33.3 times higher than those of catalysts synthesized using conventional incipient impregnation and thermal combustion methods, respectively. Furthermore, htpCC20 shows superior CO 2 selectivity (.99%) and stability (no deactivation occurs after 50 h reaction). It is believed that the dispersion of the active phase, density of surface active oxygen, and lowtemperature reducibility are the dominant factors governing the catalytic performance.

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Section: Introductionmentioning

confidence: 99%

Facile preparation of 3D ordered mesoporous CuOx–CeO2 with notably enhanced efficiency for the low temperature oxidation of heteroatom-containing volatile organic compounds

Chen

et al. 2013

RSC Adv.

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“…11,12 Growth of metal oxides in pores of mesoporous silica can result in nanowires or porous single crystals. 13,14 In this case, the crystal growth is confined by the pore size. One dimensional growth to form nanorods or nanowires can also be achieved by surface protection with ligands, 15,16 or by using porous templates such as anodic aluminum oxide.…”

Section: Introductionmentioning

confidence: 99%

Growth Mechanism of Dendritic Hematite via Hydrolysis of Ferricyanide

Green

Chiang

Greer

et al. 2017

Crystal Growth & Design

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ABSTRACT:The detailed process of the hydrolysis of ferricyanide into dendritic α-Fe2O3 (hematite) crystals with snowflake-like, feather-like and leaf-like morphologies has been investigated. [Fe(CN)6] 3-anions were found to polymerize into large, disordered soft matter aggregates at an early stage. The nucleation of hematite crystals took place near the surface of these aggregates via further hydrolysis. After the crystals grew to a certain size, branches started to appear. When the concentration of ferricyanide was low (i.e. 2 mM to 3.8 mM), growth was preferentially along the six equivalent <112 ̅ 0> directions, resulting in a flat snowflake-like shape, while high concentrations (i.e. 9 mM to 500 mM) of ferricyanide led to the growth of selective directions along the <101 ̅ 1> zone axes, forming a feather-like or leaf-like morphology. Highly selective adsorption and surface hydrolysis of [Fe(CN)6] 3-anions on α-Fe2O3 crystals was found to be a crucial process in the formation of these novel morphologies. It was found that the polymerisation of ferricyanide led to a reduction of pH value and that the formation of Fe2O3 increased pH value. The pH value of the solution at the point when the branches start to grow can significantly affect the distribution of Lewis acidic sites on different surfaces and, therefore, change the growth direction. The newly established mechanism is complementary to the classical theories of crystal growth. INTRODUCTIONControl over crystal growth orientation, exposure of selected crystal facets, and formation of novel crystal morphologies are hot topics in crystal engineering and in materials science, since the morphology and size of crystals often have a significant effect on their physio-chemical properties.

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“…Zhu et al successfully prepared various mesoporous metal oxides using organic functionalized mesoporous silica as template that involves the adsorption of inorganic precursors onto the amine-functionalized mesoporous silica materials and the thermal decomposition of the precursor to assemble the individual metal hydroxide nanoparticles in the mesochannels followed by subsequent removal of the amine-functionalized silica by hydrofluoric acid. 169 Various mesoporous metal oxides such as Cr 2 O 3 , V 2 O 5 , WO 3 , and Fe 2 O 3 with ordered structure were synthesized using this strategy by choosing appropriate metal precursor solutions.…”

Section: Component Innovationmentioning

confidence: 99%

Nanoarchitectonics for Mesoporous Materials

Ariga

Vinu

Yamauchi

et al. 2011

Bulletin of the Chemical Society of Japan

716

411

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Although mesoporous materials have well-defined pore structures, these fine materials can surprisingly be produced by employing a set of conventional and simple procedures such as mixing, heating, filtration, and washing, using low-cost materials. They can be regarded as easy-to-make bulk nanostructured materials. Mesoporous materials have great potential for use in both macroscopic applications and nanotechnology. In this account, we introduce examples of recent developments in mesoporous materials involving innovations in their components and structural designs and concentrating on our own recent progress. These examples include syntheses of mesoporous silica, metal oxides, semiconductive materials, metals, alloys, organic composites, biomaterial composites, carbon, carbon nitride, and boron nitride, as innovative components. As structural innovations for mesoporous materials, various film preparations, pore alignments, and hierarchic structures are described together with their related functions including sensing and controlled release of target molecules. Why Mesoporous Materials? Bulk Quantities and Precise StructuresThere is little doubt that nanotechnology and related technologies are making significant contributions to current research and development which will eventually be felt in our day-to-day lives. Device miniaturization in such products as cellular phones and portable computers has irrevocably changed our lifestyles. Portable devices allow us to work and communicate wherever we are in the world in contrast to the previous situation where machine operation required a human presence. Greater freedom in our work and leisure dispositions should diminish over-concentration of populations in cities and may ultimately reduce energy consumption and waste production.So far, device innovations have been due to development of top-down approaches, especially sophisticated microfabrication techniques. 17 However, those top-down techniques are not useful for materials innovation where chemical processes are used as the operating principle. Rather, so-called bottom-up approaches are expected to create novel functional materials having well-controlled structural features with nanometric precision. Bottom-up approaches rely on self-assembly processes to form selected structures through spontaneous association of atoms, molecules, clusters, and particles. 818 Furthermore, assisted assembly techniques using external influences are provided by LangmuirBlodgett (LB) method 1928 and layer-by-layer (LbL) adsorption 2936 and provide significant contributions for materials' fabrication. According to these concepts, molecular complex formation, 3741 molecular array control, 4252 and microscopic structural design 5361 have been widely investigated leading to generation of a large quantity of scientific knowledge.Ideally, materials should be produced in a series of easy processes to yield bulk quantity without loss of nanometric structural features and some categories of material already satisfy this condition. For exampl...

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Preparation of three-dimensional chromium oxide porous single crystals templated by SBA-15

Cited by 182 publications

References 14 publications

Facile preparation of 3D ordered mesoporous CuOx–CeO2 with notably enhanced efficiency for the low temperature oxidation of heteroatom-containing volatile organic compounds

Facile preparation of 3D ordered mesoporous CuOx–CeO2 with notably enhanced efficiency for the low temperature oxidation of heteroatom-containing volatile organic compounds

Growth Mechanism of Dendritic Hematite via Hydrolysis of Ferricyanide

Nanoarchitectonics for Mesoporous Materials

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