Vibrational analysis of Si(OC2H5)4 and spectroscopic studies on the formation of glasses via silica gels

Mondragón, M.A.; Castaño, V. M.; García, Manuel J.; Cármona-Téllez, S.

doi:10.1016/0924-2031(95)00002-c

Cited by 64 publications

(23 citation statements)

References 13 publications

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“…In the spectrum of the etched material, a small broad absorption band in the region $\tilde \nu $ =3600–3100 cm −1 is assignable to the stretching modes of the hydroxy groups, thus suggesting a certain amount of silanol groups (see Figure 5 S in the Supporting Information) 46. 47 In addition, the etched material shows no apparent absorption that corresponds to the CH vibration of alkyl chains in the range $\tilde \nu $ =3000–2800 cm −1 , thus indicating the absence of alkoxy groups from the silica precursor molecules, which is consistent with the solid‐state 13 C MAS NMR results 48…”

Section: Resultssupporting

confidence: 61%

A New Synthetic Route to Microporous Silica with Well‐Defined Pores by Replication of a Metal–Organic Framework

Kondo

Hall

Mallouk

et al. 2015

Chemistry A European J

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Microporous amorphous hydrophobic silica materials with well-defined pores were synthesized by replication of the metal-organic framework (MOF) [Cu3 (1,3,5-benzenetricarboxylate)2 ] (HKUST-1). The silica replicas were obtained by using tetramethoxysilane or tetraethoxysilane as silica precursors and have a micro-meso binary pore system. The BET surface area, the micropore volume, and the mesopore volume of the silica replica, obtained by means of hydrothermal treatment at 423 K with tetraethoxysilane, are 620 m(2) g(-1) , 0.18 mL g(-1) , and 0.55 mL g(-1) , respectively. Interestingly, the silica has micropores with a pore size of 0.55 nm that corresponds to the pore-wall thickness of the template MOF. The silica replica is hydrophobic, as confirmed by adsorption analyses, although the replica has a certain amount of silanol groups. This hydrophobicity is due to the unique condensation environment of the silica precursors in the template MOF.

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Section: Resultssupporting

confidence: 61%

A New Synthetic Route to Microporous Silica with Well‐Defined Pores by Replication of a Metal–Organic Framework

Kondo

Hall

Mallouk

et al. 2015

Chemistry A European J

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“…[19][20][21][23][24][25][26][27] These reactions can result in the production of SiO 2 at high temperature or lowerweight ethoxysilyl intermediates with temperatures lower than ca. 475-525 8C depending on the reaction conditions.…”

Section: Teos Pretreatment Characterizationmentioning

confidence: 99%

“…This implies a film of SiO 2 is not grown under our conditions, but rather just a modification of the surface occurs. In FTIR studies of thin silicon dioxide films, vibrational mode fingerprints appeared mainly in the 400-1200 cm À1 region [19][20]27] whereas SiÀOH [21] and SiÀC [29] bonds showed an excitation at 3700 and $1100 cm À1 , respectively. None of these peaks are present on the pretreated substrate spectrum in Figure 1.…”

Section: Teos Pretreatment Characterizationmentioning

confidence: 99%

Controlling Photoactivity in Ultrathin Hematite Films for Solar Water‐Splitting

Formal

Grätzel

Sivula

2010

Adv Funct Materials

369

361

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A promising route to increase the performance of hematite (α‐Fe2O3) photoelectrodes for solar hydrogen production through water‐splitting is to use an extremely thin layer of this visible light absorber on a nanostructured scaffold. However, the typically poor performance of ultrathin (ca. 20 nm) films of hematite has been the limiting factor in implementing this approach. Here, the surprising effect of a substrate pretreatment using tetraethoxysilicate (TEOS) is reported; it results in drastic improvements in the photoperformance of 12.5 nm thick films of hematite. These films exhibit a water oxidation photocurrent onset potential at 1.1 V versus the reversible hydrogen electrode (vs. RHE) and a plateau current of 0.63 mA cm−2 at 1.5 V vs. RHE under standard illumination conditions, representing the highest reported performance for ultrathin hematite films. In contrast, almost no photoactivity is observed for the photoanode with the same amount of hematite on an untreated substrate. A detailed study of the effects of the TEOS treatment shows that a monolayer of SiOx is formed, which acts to change the hematite nucleation and growth mechanism, increases its crystallinity, reduces the concentration of carrier trapping states of the ultrathin films, and suggests its further application to quantum‐dot and extremely‐thin‐absorber (ETA)‐type solar cells.

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“…The strong vibronic components in the range 582-586 nm indicate a relatively great vibronic coupling. An inspection of the IR data of the glasses in far IR region shows comparatively the strong δ(OSiO) or τSiOC, δOMO bending or tionion vibration modes [9] which are responsible for vibronic transitions.…”

Section: Resultsmentioning

confidence: 99%

Comparison of Optical Properties of Eu³⁺Ions in the Silica Gel Glasses Obtained by Different Preparation Techniques

et al. 1996

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Silica sol-gel glasses doped with Εu3 + ions were obtained by different preparation techniques. The absorption, emission and excitation spectra of the obtained glasses were measured in the range of 77-300 K. The energy level diagrams of Eu3+ ions were derived. An intensity analysis of f-f transitions was performed. Ιn particular, polymeric structure behaviour of europium compounds entrapped in silica gels glasses was temperature controlled during the preparation of glasses. Their optical properties were investigated.

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Vibrational analysis of Si(OC2H5)4 and spectroscopic studies on the formation of glasses via silica gels

Cited by 64 publications

References 13 publications

A New Synthetic Route to Microporous Silica with Well‐Defined Pores by Replication of a Metal–Organic Framework

A New Synthetic Route to Microporous Silica with Well‐Defined Pores by Replication of a Metal–Organic Framework

Controlling Photoactivity in Ultrathin Hematite Films for Solar Water‐Splitting

Comparison of Optical Properties of Eu³⁺Ions in the Silica Gel Glasses Obtained by Different Preparation Techniques

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Vibrational analysis of Si(OC2H5)4 and spectroscopic studies on the formation of glasses via silica gels

Cited by 64 publications

References 13 publications

A New Synthetic Route to Microporous Silica with Well‐Defined Pores by Replication of a Metal–Organic Framework

A New Synthetic Route to Microporous Silica with Well‐Defined Pores by Replication of a Metal–Organic Framework

Controlling Photoactivity in Ultrathin Hematite Films for Solar Water‐Splitting

Comparison of Optical Properties of Eu3+Ions in the Silica Gel Glasses Obtained by Different Preparation Techniques

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Comparison of Optical Properties of Eu³⁺Ions in the Silica Gel Glasses Obtained by Different Preparation Techniques