Imaging the channels in mesoporous molecular sieves with platinum

Ko, Chang Hyun; Ryoo, Ryong

doi:10.1039/cc9960002467

Cited by 104 publications

(76 citation statements)

References 7 publications

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“…Recently, Ryoo and co-workers developed a method to infiltrate pores of SBA-15 and MCM-41 with carbon or platinum, in order to synthesize ªnegativesº of the mesoporous systems. [8] In the case of the SBA-15 material, the carbon or platinum negatives retained the 2-D hexagonal structures, which exhibited very similar XRD patterns to that of SBA-15 even after complete dissolution of the silica frameworks with HF. [9] The result indicated that the main channels in SBA-15 were interconnected through smaller pores located in the channel walls.…”

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confidence: 81%

An HREM Study of Channel Structures in Mesoporous Silica SBA-15 and Platinum Wires Produced in the Channels

et al. 2001

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confidence: 81%

An HREM Study of Channel Structures in Mesoporous Silica SBA-15 and Platinum Wires Produced in the Channels

et al. 2001

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“…[25] It should be mentioned that, when in the presence of sodium ions, MCM-41 silicas often show poor hydrothermal and thermal stability due to the formation of deficient sites in the pore wall. [30,31] Several articles suggested that the tetraalkylammonium cations play a very important role in controlling highly ordered mesostructures. However, the exact role of tetraalkylammonium cations (TAA + ) for the unit-cell expansion was not well defined.…”

Section: Introductionmentioning

confidence: 99%

High‐Temperature Synthesis and Formation Mechanism of Stable, Ordered MCM‐41 Silicas by Using Surfactant Cetyltrimethylammonium Tosylate as Template

et al. 2010

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International audienceHighly ordered 2D hexagonal mesostructured silicas with thick pore walls have been directly hydrothermally synthesized at high temperatures in a range from 130 to 175 °C by using the new surfactant cetyltrimethylammonium tosylate (CTATos) as template. The mesoporous structure of the synthesized MCM-41 could be maintained after heating it to reflux in boiling water for at least 24 h. The crystallization temperature, the nature of surfactants, and the relative amount of TAAOH (tetraalkylammonium hydroxide, such as TMAOH and TEAOH) to surfactant were found to be critical parameters that affect the ordering of mesophases. On the basis of the combined characterizations of X-ray diffraction (XRD), N2 adsorption, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG), 13C cross-polarization magic-angle spinning (CPMAS) solid-state NMR spectroscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM), a new mechanism was proposed to understand the formation mechanism of highly ordered MCM-41 silicas. The enlargement of pore-wall thickness is attributed to the migration and subsequent deposition of the silicate species in the inner pore channel. This process was accelerated by the ion-exchange interaction of tetraalkylammonium cations (TAA+) on CTA+ cations

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“…Ko and Ryoo showed, instead, how wet impregnation with metal-salt solution allowed the formation of metallic nanowires within the pores of mesoporous materials, which could also be extracted from the template. [44] This technique has then been used to produce a variety of nanowires of different metals. [45,46] The reduction of the salts was performed by UV irradiation.…”

Section: Templatingmentioning

confidence: 99%

Ultrathin Nanowires—A Materials Chemistry Perspective

2009

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The recent years have seen an explosive interest in one‐dimensional nanostructures1, as testified by the number of citations this field has accrued; as customary, its blossoming was enabled by chemical breakthroughs that allowed the reproducible and affordable synthesis of such structures.2, 3 The limitations of those syntheses was in the diameter of the nanowires that it could produce (hardly < 10 nm), and in the use of expensive and low‐yield techniques, such as chemical vapor deposition (CVD). This paper attempts to summarize the very recent chemical breakthroughs that have allowed the production of ultrathin nanowires, often in solution, and often in gram‐scale quantities. By no means is this a comprehensive coverage of the field, which can in part be found in other excellent reviews1, 2, 4–6 but a selection of those contributions that we feel would most help put this emerging field in perspective. We will review the various synthetic strategies, their pros and cons, and we will give our best guesses as to the future directions of the field and what we can expect from it.

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Imaging the channels in mesoporous molecular sieves with platinum

Cited by 104 publications

References 7 publications

An HREM Study of Channel Structures in Mesoporous Silica SBA-15 and Platinum Wires Produced in the Channels

An HREM Study of Channel Structures in Mesoporous Silica SBA-15 and Platinum Wires Produced in the Channels

High‐Temperature Synthesis and Formation Mechanism of Stable, Ordered MCM‐41 Silicas by Using Surfactant Cetyltrimethylammonium Tosylate as Template

Ultrathin Nanowires—A Materials Chemistry Perspective

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