Hydrogen transport property of polymer-derived cobalt cation-doped amorphous silica

Tada, S.; Ando, Shiori; Asaka, Toru; Daiko, Yusuke; Honda, Sawao; Bernard, Samuel; Iwamoto, Yuji

doi:10.1039/d0qi01035a

Cited by 7 publications

(8 citation statements)

References 35 publications

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Section: Resultsmentioning

confidence: 99%

“…Moreover, metallic Co was not formed under the present heat treatment conditions, and thus formation of Co(III) via the disproportionation reaction (3Co 2+ → 2Co 3+ + Co) was excluded. It should be also noted that the oxidation state of the Co cation in the polymer-derived Co-doped amorphous SiO 2 was completely divalent [40]. It is well known that the Fenton reaction is the Fe(III/II)-catalyzed oxidation of organic compounds (RH) via generation of highly reactive radical species (•OH) in the presence of H 2 O 2 [41,42]:…”

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confidence: 99%

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Reversible Redox Property of Co(III) in Amorphous Co-doped SiO2/γ-Al2O3 Layered Composites

et al. 2020

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This paper reports on a unique reversible reducing and oxidizing (redox) property of Co(III) in Co-doped amorphous SiO2/γ-Al2O3 composites. The Fenton reaction during the H2O2-catalyzed sol–gel synthesis utilized in this study lead to the partial formation of Co(III) in addition to Co(II) within the composites. High-resolution transmission electron microscopy (HRTEM) and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) analyses for the composite powder sample with a composition of Al:Si:Co = 85:10:5 showed the amorphous state of the Co-doped SiO2 that modified γ-Al2O3 nanocrystalline surfaces. In situ X-ray absorption fine structure (XAFS) spectroscopic analysis suggested reversible redox reactions of Co species in the composite powder sample during heat-treatment under H2 at 500 °C followed by subsequent cooling to RT under Ar. Further analyses by in situ IR spectroscopy combined with cyclic temperature programmed reduction/desorption (TPR/TPD) measurements and X-ray photoelectron spectroscopic (XPS) analysis revealed that the alternating Co(III)/(II) redox reactions were associated with OH formation (hydrogenation)-deformation (dehydrogenation) of the amorphous aluminosilicate matrix formed in situ at the SiO2/γ-Al2O3 hetero interface, and the redox reactions were governed by the H2 partial pressure at 250–500 °C. As a result, a supported mesoporous γ-Al2O3/Co-doped amorphous SiO2/mesoporous γ-Al2O3 three-layered composite membrane exhibited an H2-triggered chemical valve property: mesopores under H2 flow (open) and micropores under He flow (closure) at 300–500 °C.

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Section: Resultsmentioning

confidence: 99%

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confidence: 99%

Reversible Redox Property of Co(III) in Amorphous Co-doped SiO2/γ-Al2O3 Layered Composites

et al. 2020

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“…In order to analyze and describe the adsorption performance of ZIF-8/yeast towards Eu(III), pseudo-first-order, pseudo-secondorder, Elovich pattern and intra-particle diffusion pattern 43 were also adopted to reveal the adsorption mechanism of Eu(III). These patterns were described using the following equation: Pseudo-first-order pattern: ln(q e À q t ) = ln q e À k 1 Át (12)…”

Section: Influence Of Adsorption Kineticsmentioning

confidence: 99%

Enhanced removal performance and evaluative interaction mechanism of europium from an aqueous medium by microbial yeast-decorated zeolitic imidazolate framework hybrids

Zong

Shao

et al. 2023

J. Mater. Chem. C

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“…Such a sample is referred to as "X-ray amorphous." [7][8][9] Due to their higher energy and lack of long-range order, such amorphous phases tend to transform into their more stable crystalline form. [3] Amorphous phases can be stabilized, for example, by poylmers, which can embed the amorphous drug in a matrix.…”

Section: Introductionmentioning

confidence: 99%

“…[ 1,6 ] The presence of a noncrystalline solid can typically be identified by the loss of clear Bragg reflections in the X‐ray powder pattern of the corresponding solid. Such a sample is referred to as “X‐ray amorphous.” [ 7–9 ] Due to their higher energy and lack of long‐range order, such amorphous phases tend to transform into their more stable crystalline form. [ 3 ] Amorphous phases can be stabilized, for example, by poylmers, which can embed the amorphous drug in a matrix.…”

Section: Introductionmentioning

confidence: 99%

You cannot fight the pressure: Structural rearrangements of active pharmaceutical ingredients under magic angle spinning

Scheidel

Östreicher

Mark

et al. 2022

Magnetic Reson in Chemistry

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Although solid‐state nuclear magnetic resonance (NMR) is a versatile analytical tool to study polymorphs and phase transitions of pharmaceutical molecules and products, this work summarizes examples of spontaneous and unexpected (and unwanted) structural rearrangements and phase transitions (amorphous‐to‐crystalline and crystalline‐to‐crystalline) under magic angle spinning (MAS) conditions, some of them clearly being due to the pressure experienced by the samples. It is widely known that such changes can often be detected by X‐ray powder diffraction (XRPD); here, the capability of solid‐state NMR experiments with a special focus on 1H‐13C frequency‐switched Lee–Goldburg heteronuclear correlation (FSLG HETCOR)/MAS NMR experiments to detect even subtle changes on a molecular level not observable by conventional 1D NMR experiments or XRPD is presented. Furthermore, it is shown that a polymorphic impurity combined with MAS can induce a crystalline‐to‐crystalline phase transition. This showcases that solid‐state NMR is not always noninvasive and such changes upon MAS should be considered in particular when compounds are studied over longer time spans.

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Hydrogen transport property of polymer-derived cobalt cation-doped amorphous silica

Abstract: The effect of local structure of Co-doped amorphous silica on hydrogen transport property was studied aiming to improve high-temperature hydrogen-permselectivity of microporous amorphous silica-based membranes. Co-doped silica materials with measured...

Cited by 7 publications

References 35 publications

Reversible Redox Property of Co(III) in Amorphous Co-doped SiO2/γ-Al2O3 Layered Composites

Reversible Redox Property of Co(III) in Amorphous Co-doped SiO2/γ-Al2O3 Layered Composites

Enhanced removal performance and evaluative interaction mechanism of europium from an aqueous medium by microbial yeast-decorated zeolitic imidazolate framework hybrids

You cannot fight the pressure: Structural rearrangements of active pharmaceutical ingredients under magic angle spinning

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