Surface modification and porosimetry of vertically aligned hexagonal mesoporous silica films

Robertson, Calum; Lodge, Andrew W.; Basa, P.; Carravetta, Marina; Hector, Andrew L.; Kashtiban, Reza J.; Sloan, Jeremy; Smith, David C.; Spencer, Joseph H.; Walcarius, Alain

doi:10.1039/c6ra23059h

Cited by 12 publications

(10 citation statements)

References 62 publications

(97 reference statements)

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“… 39 , 40 Highly polar solvents such as water are likely to produce large hysteresis because of interaction with the hydroxyl groups on the pore wall during the adsorption–desorption process. 41 Changes in refractive index values were measured during the experiment, which allowed for the volume fraction of toluene present within the pores to be calculated using the Lorentz–Lorenz effective medium approximation. 39 …”

Section: Resultsmentioning

confidence: 99%

Increasing the Diameter of Vertically Aligned, Hexagonally Ordered Pores in Mesoporous Silica Thin Films

et al. 2022

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The variation in pore size in mesoporous films produced by electrochemically assisted self-assembly (EASA) with the surfactant chain length is described. EASA produces a hexagonal array of pores perpendicular to the substrate surface by using an applied potential to organize cationic surfactants and the resultant current to drive condensation in a silica sol. Here, we show that a range of pore sizes between 2 and 5 nm in diameter is available with surfactants of the form [Me 3 NC n H 2 n +1 ]Br, with alkyl chain lengths between C 14 and C 24 . The film quality, pore order, pore size, and pore accessibility are probed with a range of techniques.

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Section: Resultsmentioning

confidence: 99%

Increasing the Diameter of Vertically Aligned, Hexagonally Ordered Pores in Mesoporous Silica Thin Films

et al. 2022

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“…We have shown that the silica films contain pores which are aligned nearly perpendicular to the film without significant interconnection using TEM . We have characterized the films using ellipsometric porosimetry demonstrating a high pore accessibility (measured porosity 38%) and determined the pore diameter to be 1.4 nm which is within error the same as the pore diameter determined from STEM images . These films were further optimized to reduce defects at a range of scales to ensure that the largest possible fraction of the finished electrodes is only accessible via the ≈1.5 nm pores (see the SI).…”

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confidence: 87%

“…13 We have characterized the films using ellipsometric porosimetry demonstrating a high pore accessibility (measured porosity 38%) and determined the pore diameter to be 1.4 nm which is within error the same as the pore diameter determined from STEM images. 14 These films were further optimized to reduce defects at a range of scales to ensure that the largest possible fraction of the finished electrodes is only accessible via the ≈1.5 nm pores (see the SI). We estimate, using a combination of SEM and TEM imaging, that more than 95% of the electrode is covered by mesoporous silica with ≈1.5 nm pores.…”

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Exploration of the Smallest Diameter Tin Nanowires Achievable with Electrodeposition: Sub 7 nm Sn Nanowires Produced by Electrodeposition from a Supercritical Fluid

et al. 2018

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Electrodeposition of Sn from supercritical difluoromethane has been performed into anodic alumina templates with pores down to 3 nm in diameter and into mesoporous silica templates with pores of diameter 1.5 nm. Optimized deposits have been characterized using X-ray diffraction, scanning electron microscopy, and scanning transmission electron microscopy (bright field, high-angle annular dark field, and energy-dispersive X-ray elemental mapping). Crystalline 13 nm diameter Sn nanowires have been electrodeposited in symmetric pore anodic alumina. Direct transmission electron microscopy evidence of sub 7 nm Sn nanowires in asymmetric anodic alumina has been obtained. These same measurements present indirect evidence for electrodeposition through 3 nm constrictions in the same templates. A detailed transmission electron microscopy study of mesoporous silica films after Sn deposition is presented. These indicate that it is possible to deposit Sn through the 1.5 nm pores in the mesoporous films, but that the nanowires formed are not stable. Suggestions of why this is the case and how such extreme nanowires could be stabilized are presented.

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“…This procedure can be done in a variety of ways but in the specific example cited here, electrochemical methods were used. [5] This system concerns pore alignment in 2D hexagonal mesoporous thin Table 1. S stands for Surfactant, I stands for inorganic species, X stands for mediating ions, After.…”

Section: P E R S O N a L A C C O U N T T H E C H E M I C A L R E C O R Dmentioning

confidence: 99%

A Review of Recent Developments of Mesoporous Materials

Suib

2017

The Chemical Record

102

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This personal account concerns novel recent discoveries in the area of mesoporous materials. Most of the papers discussed have been published within the last two to three years. A major emphasis of most of these papers is the synthesis of unique mesoporous materials by a variety of synthetic methods. Many of these articles focus on the control of the pore sizes and shapes of mesoporous materials. Synthetic methods of various types have been used for such control of porosity including soft templating, hard templating, nano-casting, electrochemical methods, surface functionalization, and trapping of species in pores. The types of mesoporous materials range from carbon materials, metal oxides, metal sulfides, metal nitrides, carbonitriles, metal organic frameworks (MOFs), and composite materials. The vast majority of recent publications have centered around biological applications with a majority dealing with drug delivery systems. Several other bio-based articles on mesoporous systems concern biomass conversion and biofuels, magnetic resonance imaging (MRI) studies, ultrasound therapy, enzyme immobilization, antigen targeting, biodegradation of inorganic materials, applications for improved digestion, and antitumor activity. Numerous nonbiological applications of mesoporous materials have been pursued recently. Some specific examples are photocatalysis, photo-electrocatalysis, lithium ion batteries, heterogeneous catalysis, extraction of metals, extraction of lanthanide and actinide species, chiral separations and catalysis, capturing and the mode of binding of carbon dioxide (CO ), optical devices, and magneto-optical devices. Of this latter class of applications, heterogeneous catalysis is predominant. Some of the types of catalytic reactions being pursued include hydrogen generation, selective oxidations, aminolysis, Suzuki coupling and other coupling reactions, oxygen reduction reactions (ORR), oxygen evolution reactions (OER), and bifunctional catalysis. For perspective, there have been over 40,000 articles on mesoporous materials published in the last 4 years and about 1388 reviews. By no means is this personal account thorough or all inclusive. One objective has been to choose a variety of articles of different types to obtain a flavor of the breadth of diversity involved in the area of mesoporous materials.

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Surface modification and porosimetry of vertically aligned hexagonal mesoporous silica films

Abstract: Grafting vertically aligned mesoporous silica films with small organosilane precursors increases pore hydrophobicity, whereas larger reagents change only the film surfaces.

Cited by 12 publications

References 62 publications

Increasing the Diameter of Vertically Aligned, Hexagonally Ordered Pores in Mesoporous Silica Thin Films

Increasing the Diameter of Vertically Aligned, Hexagonally Ordered Pores in Mesoporous Silica Thin Films

Exploration of the Smallest Diameter Tin Nanowires Achievable with Electrodeposition: Sub 7 nm Sn Nanowires Produced by Electrodeposition from a Supercritical Fluid

A Review of Recent Developments of Mesoporous Materials

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