Al/Fe isomorphic substitution versus Fe2O3 clusters formation in Fe-doped aluminosilicate nanotubes (imogolite)

Shafia, Ehsan; Esposito, Serena; Manzoli, Maela; Chiesa, Mario; Tiberto, P.; Barrera, Gabriele; Ménard, Gabriel; Allia, Paolo; Freyria, Francesca Stefania; Garrone, Edoardo; Bonelli, Barbara

doi:10.1007/s11051-015-3130-2

Cited by 34 publications

(34 citation statements)

References 44 publications

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“…In order to confirm this hypothesis, the absence of Fe 2+ species was checked by Mössbauer spectroscopy with Fe2.5-MTd sample ( Figure 5): similar to previous reports of Fe-doped TiO2 materials [58][59][60]. Since surface Fe 2+ species would undergo a faster Fenton reaction, Fe2.5-MTd sample was incubated for 20 min with ascorbic acid (AA).…”

Section: Ao7 Degradation Tests: Catalytic Behavior Of the Samples In supporting

confidence: 62%

Pure and Fe-Doped Mesoporous Titania Catalyse the Oxidation of Acid Orange 7 by H2O2 under Different Illumination Conditions: Fe Doping Improves Photocatalytic Activity under Simulated Solar Light

et al. 2017

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A sample of mesoporous TiO 2 (MT, specific surface area = 150 m 2 ·g −1 ) and two samples of MT containing 2.5 wt.% Fe were prepared by either direct synthesis doping (Fe2.5-MTd) or impregnation (Fe2.5-MTi). Commercial TiO 2 (Degussa P25, specific surface area = 56 m 2 ·g −1 ) was used both as a benchmark and as a support for impregnation with either 0.8 or 2.5 wt.% Fe (Fe0.80-IT and Fe2.5-IT). The powders were characterized by X-ray diffraction, N 2 isotherms at −196 • C, Energy Dispersive X-ray (EDX) Spectroscopy, X-ray Photoelectron Spectroscopy (XPS), Diffuse Reflectance (DR) ultra-violet (UV)-Vis and Mössbauer spectroscopies. Degradation of Acid Orange 7 (AO7) by H 2 O 2 was the test reaction: effects of dark-conditions versus both UV and simulated solar light irradiation were considered. In dark conditions, AO7 conversion was higher with MT than with Degussa P25, whereas Fe-containing samples were active in a (slow) Fenton-like reaction. Under UV light, MT was as active as Degussa P25, and Fe doping enhanced the photocatalytic activity of Fe2.5-MTd; Fe-impregnated samples were also active, likely due to the occurrence of a photo-Fenton process. Interestingly, the Fe2.5-MTd sample showed the best performance under solar light, confirming the positive effect of Fe doping by direct synthesis with respect to impregnation.

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Section: Ao7 Degradation Tests: Catalytic Behavior Of the Samples In supporting

confidence: 62%

Pure and Fe-Doped Mesoporous Titania Catalyse the Oxidation of Acid Orange 7 by H2O2 under Different Illumination Conditions: Fe Doping Improves Photocatalytic Activity under Simulated Solar Light

et al. 2017

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“…13,14 Finally, both inner and outer hydroxylated surfaces offer interesting possibilities for surface functionalization. INTs can thus be rendered amphiphilic by replacing their inner silanol or germanol moiety by a functionalized one, 15 or by grafting molecular compounds on the outer aluminum wall.…”

Section: +mentioning

confidence: 99%

Effect of Ionic Strength on the Bundling of Metal Oxide Imogolite Nanotubes

et al. 2017

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Significant developments have been proposed over the past decade in the synthesis of aluminosilicate and aluminogermanate imogolite-like nanotubes. But, while liquid phase synthesis is well-controlled, it is not the case for the nanotube arrangement in the dry state. In particular, nanotubes are found to self-assemble in bundles of various sizes, which may impact the properties of the final product. Here, we investigate the effect of ionic strength on bundling of aluminogermanate single-walled imogolite nanotubes (Ge-SWINT) in aqueous suspensions and in the resulting powders after solvent evaporation. The nanotube arrangement as a function of salt concentration was studied by X-ray scattering experiments and simulations. In aqueous suspension, nanotubes bundling occurs only at high ionic strength (IS > 8 × 10–2 mol·L–1), while beyond this threshold, the increase of electrostatic repulsions induces a complete stabilization of individual nanotubes. After solvent evaporation, nanotube arrangement is shown to be dictated principally by the initial concentration of salt. Beyond an ionic strength of ∼10–3 mol·L–1 in the starting suspension, all Ge-SWINT samples tend to form large bundles in powder, whose lattice parameters are independent of the initial salt concentrations. These experimental results clearly show that the positive surface charge of imogolite can be used to control nanotubes bundling by anion condensation.

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“…In the case of chrysotile to date there are series of reports on change of Mg and (or) Si by Fe,,, Ni, Ti,, and Ge . Halloysite and imogolite were successfully doped by Ge, and Fe as well.…”

Section: Introductionmentioning

confidence: 99%

Cation Redistribution along the Spiral of Ni‐Doped Phyllosilicate Nanoscrolls: Energy Modelling and STEM/EDS Study

et al. 2019

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Here, we study the stress‐induced self‐organization of Mg2+ and Ni2+ cations in the crystal structure of multiwalled (Mg1–x,Nix)3Si2O5(OH)4 phyllosilicate nanoscrolls. The phyllosilicate layer strives to compensate size and surface energy difference between the metal oxide and silica sheets by curling. But as soon as the layer grows, the scrolling mechanism becomes a spent force. An energy model proposes secondary compensation of strain: two cations distribute along the nanoscroll spiral in accordance with preferable radii of curvature. To reveal this, we study synthetic (Mg1–x,Nix)3Si2O5(OH)4 nanoscrolls by the scanning transmission electron microscopy/energy‐dispersive X‐ray spectroscopy (STEM/EDS) technique. For a number of scrolls, we have found indeed a change of Ni concentration with increase in distance from the nanoscroll central axis. The concentration gradient, according to our estimates, can reach 50 at.% over 25 nm of the wall thickness.

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Al/Fe isomorphic substitution versus Fe2O3 clusters formation in Fe-doped aluminosilicate nanotubes (imogolite)

Cited by 34 publications

References 44 publications

Pure and Fe-Doped Mesoporous Titania Catalyse the Oxidation of Acid Orange 7 by H2O2 under Different Illumination Conditions: Fe Doping Improves Photocatalytic Activity under Simulated Solar Light

Pure and Fe-Doped Mesoporous Titania Catalyse the Oxidation of Acid Orange 7 by H2O2 under Different Illumination Conditions: Fe Doping Improves Photocatalytic Activity under Simulated Solar Light

Effect of Ionic Strength on the Bundling of Metal Oxide Imogolite Nanotubes

Cation Redistribution along the Spiral of Ni‐Doped Phyllosilicate Nanoscrolls: Energy Modelling and STEM/EDS Study

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