Effect of surface hydroxyl groups on heat capacity of mesoporous silica

Marszewski, Michal; Butts, Danielle M.; Lan, Esther H.; Yan, Yan; King, Sophia C.; McNeil, Patricia E.; Galy, Tiphaine; Dunn, Bruce; Tolbert, Sarah H.; Hu, Yongjie; Pilon, Laurent

doi:10.1063/1.5027080

Cited by 12 publications

(12 citation statements)

References 25 publications

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“…Indeed, in this case, the band gap values were determined from the extrapolation of the slopes of the modified K-M functions versus energy to zero absorption (indirect allowed transition method, n = 2). However, the authors found that the TiO2/SBA-15 catalyst revealed an increase in the Eg (3.30 eV), which was ascribed to the smaller size of TiO2 particles in the prepared catalyst supported on SBA-15 [36,37]. In particular, in this study the variation of band gap (ΔEg) had not the same extent depending on the different titania precursors, but the following trend was observed: P25 > Kronos VLP > Mirkat 211.…”

Section: Discussionmentioning

confidence: 99%

Multifunctional and Environmentally Friendly TiO2–SiO2 Mesoporous Materials for Sustainable Green Buildings

et al. 2019

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This work deals with the formulation of environmentally friendly, cheap, and readily-available materials for green building applications, providing the function of air purificator by improving the safety and the comfort of an indoor environment. High surface area TiO2–SiO2 samples, prepared by a simple, cost effective, and scalable synthetic approach, proved to be effective in maximizing the properties of each component, i.e., the photocatalytic properties of titania and the high surface area of silica. TiO2 was introduced onto an ordered mesoporous silica Santa Barbara Amorphous-15 (SBA-15), that is featured by interesting insulating features, by using an incipient wetness impregnation method. The photocatalytic activity was evaluated in gas phase oxidation of ethylbenzene, which was selected as model volatile organic compound (VOC) molecule. The morphological, textural and structural features along with the electronic properties, the hydrophilicity and heat capacity of the materials were investigated in depth by scanning electron microscopy, powder X-ray diffraction, N2 physisorption, diffuse reflectance UV-Vis, FT-IR spectroscopies, and modulated DSC (MDSC) dynamic scan. Outstanding performances in the ethylbenzene abatement results are promising for further application in the green building sector.

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Section: Discussionmentioning

confidence: 99%

Multifunctional and Environmentally Friendly TiO2–SiO2 Mesoporous Materials for Sustainable Green Buildings

et al. 2019

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“…The SS solution can be expressed as mSiO 2 •nH 2 O, and possesses a large amount of water and hydroxyl group. 31 The hydroxyl groups can bind to the alumina due to its hydrophilic behavior. 32 TO can be expressed as CH 3 CH 2 OSi(OCH 2 CH 3 ) 3 , and possesses a large amount of -OCH 2 CH 3 moieties.…”

Section: Physical Propertiesmentioning

confidence: 99%

Enhanced 3D printed alumina ceramic cores via impregnation

Colombo

et al. 2021

J Am Ceram Soc

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3D-printed alumina ceramic cores often face the problem of low flexural strength at its application temperature of 1500°C, and the requirements on porosity and strength limit its fabrication process. In this research, three types of solutions were employed to impregnate the ceramics to improve the strength of the 3Dprinted alumina ceramic cores. The results showed that silica sol (SS), tetraethyl orthosilicate (TO), and 3-(Trimethoxysilyl)propyl methacrylate (PM) all could improve the (room temperature) flexural strength of the 3D printed ceramics effectively compared to the control sample (CS) without impregnation, and the SS solution could improve the high temperature flexural strength at 1500°C greatly compared to other solutions. The improvement in strength was due to the introduction of Si, which formed a stable mullite phase during the sintering process. Computed tomography (CT) analysis showed there is no cracks formed in the ceramic cores impregnated with the SS solution, and they exhibited the overall best performance (21.2 ± 0.8 vol% open porosity, shrinkage of 3.2 ± 0.3% in the X direction, 3.4 ± 0.2% in the Y direction, 2.1 ± 0.4% in the Z direction, room temperature flexural strength of 85.7 ± 6.9 MPa, and 1500°C flexural strength of 19.2 ± 1.1 MPa).

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“…We note again that thermodynamic quantities such as heat capacity do not apply on the ultrafast timescale, but considering an effective heat capacity provides a reasonable explanation for our observations. Nanoscale silica materials have specific heat capacities below 1 J/g K, 40 whereas solvents typically have higher heat capacities. In these specific nanomaterials, the estimated specific heat capacity for silica in the coated silica samples ranges from 0.73 to 0.84 J/g K, 40 depending on porosity, and the heat capacity of the ligandcoated substrates can range between 1.6 J/mL K and 4.18 J/g K (Tables 1 & S2).…”

Section: Acs Applied Materials and Interfacesmentioning

confidence: 99%

“…Nanoscale silica materials have specific heat capacities below 1 J/g K, 40 whereas solvents typically have higher heat capacities. In these specific nanomaterials, the estimated specific heat capacity for silica in the coated silica samples ranges from 0.73 to 0.84 J/g K, 40 depending on porosity, and the heat capacity of the ligandcoated substrates can range between 1.6 J/mL K and 4.18 J/g K (Tables 1 & S2). 34 Additional information about the heat capacity estimates for these samples can be found in the Supporting Information.…”

Section: Acs Applied Materials and Interfacesmentioning

confidence: 99%

“…The difference in heating response among the silica-, mesoporous silica-, and ligand-coated substrates most likely arises because of the differences in the effective heat capacity of the local environments around the molecules adsorbed to the gold surface. Clearly, silica supports affect the localized heating (34,35) 0.8−1.4 a g −1 (40) 0.733 g −1 (40) a Heat capacity for mesoporous silica AuNRs was estimated based on pore size, where the range given estimates a 25−33% solvent (EtOH) contribution to the heat capacity. b Estimated citrate-capped AuNP thermal property values based upon the measurements of the other ligand shells, including CTAB, polyethylene glycol, and polystyrene.…”

Section: ■ Conclusionmentioning

confidence: 99%

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Effect of Silica Supports on Plasmonic Heating of Molecular Adsorbates as Measured by Ultrafast Surface-Enhanced Raman Thermometry

Keller

Kang

Haynes

et al. 2018

ACS Appl. Mater. Interfaces

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Plasmonic materials show great potential for selective photocatalysis under relatively mild reaction conditions. However, the catalytic activity of these plasmonic catalysts can also depend upon the support material that stabilizes the catalysts, where the composition of the catalytic support may change the overall photocatalytic efficiency and yield. It is unknown how changes in the support material may change the plasmon-driven photocatalysis, which may be initiated by plasmon-derived hot carriers, localized heating, or enhanced electromagnetic fields. Herein, we probe the effects of catalytic supports on heating in plasmon-driven catalysis by examining various gold nanoparticle oxide systems. We use ultrafast surface-enhanced Raman thermometry to measure the effective temperature, equivalent to the vibrational kinetic energy, of reporter molecules located between plasmonic gold nanostructures and local environments ranging from ligands to mesoporous silica shells to silica shells. Upon photoexcitation, the transient effective temperature, equivalent to the energy deposited into a vibrational mode, of adsorbed molecules on the silica-coated samples increases, and the energy quickly dissipates within 3 ps. However, the baseline effective temperature that arises from the surface-enhanced Raman spectroscopy probing process depends upon the encapsulant, where the energy deposition differs by 200–300 K between the ligand-coated (citrate or CTAB) and the silica-coated samples. Adsorbates surrounded by a silica shell experience significantly higher effective temperatures than the adsorbates surrounded by ligands or solvent, likely because of the differing effective heat capacities of these media. Taken together, this work shows that a silica support impacts the localized heating of molecular adsorbates on the gold surface and may play a role in enhanced plasmonic photocatalysis because of increased thermal contributions.

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Effect of surface hydroxyl groups on heat capacity of mesoporous silica

Cited by 12 publications

References 25 publications

Multifunctional and Environmentally Friendly TiO2–SiO2 Mesoporous Materials for Sustainable Green Buildings

Multifunctional and Environmentally Friendly TiO2–SiO2 Mesoporous Materials for Sustainable Green Buildings

Enhanced 3D printed alumina ceramic cores via impregnation

Effect of Silica Supports on Plasmonic Heating of Molecular Adsorbates as Measured by Ultrafast Surface-Enhanced Raman Thermometry

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