The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Yoshio Bando - One of the best experts on this subject based on the ideXlab platform.
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conversion of a 2d lepidocrocite type layered titanate into its 1d nanowire form with enhancement of cation exchange and photocatalytic performance
Inorganic Chemistry, 2019Co-Authors: Mohamed Esmat, Ahmed A Farghali, S I Eldek, M H Khedr, Yusuke Yamauchi, Yoshio BandoAbstract:Layered Titanates with one-dimensional (1D) shapes have been an important class of nanomaterials due to their combination of 1D and 2D fascinating properties. Among many layered Titanates, lepidocrocite-type layered Titanates have significant advantages such as superior intercalation and exfoliation properties, while the synthesis of the 1D-shape forms is still challenging. Here, we report on a facile one-pot hydrothermal conversion of a lepidocrocite-type layered titanate into the corresponding nanowire-shape form. The reaction mechanism involves the decomposition of the starting layered titanate into 1D small segments which assemble into the nanowire. This new nanowire shows properties resulting from the combination of 1D and 2D nanostructural features, excellent cation exchange ability, and high photoinduced charge separation and photocatalytic efficiency. As a demonstration, we evaluate the nanowire as a sequestrating material capable of collecting toxic cations, like Cd, from water and photoreducing them (immobilizing them tightly). We find that the nanowire shows an efficient and ultrafast photoimmobilization activity, whereas the starting layered titanate and a benchmark TiO photocatalyst (P25) show no activity under the identical conditions. The photoimmobilization rate (within 1 min) is considerably faster than the cation exchange rates reported for state-of-the-art cation exchangers (with no photoimmobilization ability). The nanowire used for photoimmobilization reactions is easily recovered from water by decantation, showing the possible practical use for safe disposal of toxic cations in the environment.
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structural features of titanate nanotubes nanobelts revealed by raman x ray absorption fine structure and electron diffraction characterizations
Journal of Physical Chemistry B, 2005Co-Authors: Katsutoshi Fukuda, Takayoshi Sasaki, Minoru Osada, Yoshio BandoAbstract:High-purity nanotubes and nanobelts could be controllably obtained in hydrothermal treatments of anatase TiO2 in concentrated NaOH solution depending on treating temperature and duration. Their structural features were studied employing X-ray diffraction, Raman, X-ray absorption fine structure, and electron diffraction characterizations. The results reveal that both the nanotubes and nanobelts might be of layered titanate structure. The similarity and difference among the nanotubes/nanobelts and other bulk Titanates represented by trititanate H2Ti3O7 and lepidocrocite-type H0.7Ti1.825□0.175O4.0·H2O were also presented.
Helmer Fjellvåg - One of the best experts on this subject based on the ideXlab platform.
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Lanthanum titanate and lithium lanthanum titanate thin films grown by atomic layer deposition
Journal of Materials Chemistry, 2010Co-Authors: Titta Aaltonen, Mari Alnes, Ola Nilsen, Leila Costelle, Helmer FjellvågAbstract:Thin films of lanthanum titanate and lithium lanthanum titanate (LLT) have been grown by atomic layer deposition (ALD). Studies on the growth of lanthanum Titanates showed that the lanthanum deposition rate is reduced when the titanium oxide and lanthanum oxide processes are combined, leading to higher titanium contents in the films. The precursor systems used for deposition of lanthanum Titanates were TiCl4 + water and La(thd)3 (thd = 2,2,6,6-tetramethyl-3,5-heptanedione) + ozone. Lithium was introduced into the material in order to deposit LLT by using lithium tert-butoxide (LiOtBu) and water as precursors. The deposited films were analyzed by time-of-flight elastic recoil detection analysis (TOF-ERDA), secondary ion mass spectrometry (SIMS), X-ray fluorescence (XRF), X-ray reflectivity (XRR) and X-ray diffraction (XRD). TOF-ERDA gave the film composition of Li0.32La0.30TiOz at saturation conditions.
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syntheses structures and magnetic properties of nickel doped lepidocrocite Titanates
Inorganic Chemistry, 2009Co-Authors: Poul Norby, Hiroshi Okamoto, Helmer FjellvågAbstract:Ni-doped titanate CsxTi2−x/2Nix/2O4 and its protonic derivative HxTi2−x/2Nix/2O4·xH2O (x = 0.7) were synthesized and characterized by means of synchrotron X-ray diffraction, Raman scattering, X-ray photoelectron spectroscopy (XPS), and magnetic measurements. CsxTi2−x/2Nix/2O4 crystallizes in an orthorhombic structure (space group Immm), consisting of infinite two-dimensional (2D) host layers of the lepidocrocite (γ-FeOOH) type. The substitution of Ni atoms for Ti in the 2D octahedral layers results in negative charges that are compensated by interlayer Cs+ ions. Raman scattering and XPS indicate that local structural perturbations are induced upon exchange of interlayer Cs ions with protons H3O+. Magnetic measurements reveal typical paramagnetism induced by Ni substitution; the effective paramagnetic moment μeff = 1.57(1) μB and Curie−Weiss temperature −2.51(1) K are obtained for HxTi2−x/2Nix/2O4·xH2O. Ni- and Mg-codoped Titanates CsxTi2−x/2(NiyMg1−y)x/2O4 (x = 0.7, 0 ≤ y ≤ 1) were also reported. The crys...
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protonic titanate derived from csxti2 x 2mgx 2o4 x 0 7 with lepidocrocite type layered structure
Journal of Materials Chemistry, 2009Co-Authors: Helmer Fjellvåg, Poul NorbyAbstract:A layered titanate CsxTi2−x/2Mgx/2O4 (x = 0.7) with lepidocrocite (γ-FeOOH)-type layered structure was prepared via solid-state reaction. Extraction of both Mg2+ ions in the host layers and interlayer Cs+ ions was achieved during an acid-exchange process, producing a new protonic titanate HxTi2−x/2O4−x/2·H2O. This phase was distinguished from isomorphous related compounds in terms of removable lattice Mg and O atoms. The protonic titanate HxTi2−x/2O4−x/2·H2O showed excellent exfoliation/delamination reactivity upon intercalating organic amine ions as well as the ability to produce single two-dimensional titanate nanosheets with small thickness of about 1 nm. These findings offered a new clue for understanding the physicochemical properties of lattice dopants in lepidocrocite Titanates.
Mohamed Esmat - One of the best experts on this subject based on the ideXlab platform.
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conversion of a 2d lepidocrocite type layered titanate into its 1d nanowire form with enhancement of cation exchange and photocatalytic performance
Inorganic Chemistry, 2019Co-Authors: Mohamed Esmat, Ahmed A Farghali, S I Eldek, M H Khedr, Yusuke Yamauchi, Yoshio BandoAbstract:Layered Titanates with one-dimensional (1D) shapes have been an important class of nanomaterials due to their combination of 1D and 2D fascinating properties. Among many layered Titanates, lepidocrocite-type layered Titanates have significant advantages such as superior intercalation and exfoliation properties, while the synthesis of the 1D-shape forms is still challenging. Here, we report on a facile one-pot hydrothermal conversion of a lepidocrocite-type layered titanate into the corresponding nanowire-shape form. The reaction mechanism involves the decomposition of the starting layered titanate into 1D small segments which assemble into the nanowire. This new nanowire shows properties resulting from the combination of 1D and 2D nanostructural features, excellent cation exchange ability, and high photoinduced charge separation and photocatalytic efficiency. As a demonstration, we evaluate the nanowire as a sequestrating material capable of collecting toxic cations, like Cd, from water and photoreducing them (immobilizing them tightly). We find that the nanowire shows an efficient and ultrafast photoimmobilization activity, whereas the starting layered titanate and a benchmark TiO photocatalyst (P25) show no activity under the identical conditions. The photoimmobilization rate (within 1 min) is considerably faster than the cation exchange rates reported for state-of-the-art cation exchangers (with no photoimmobilization ability). The nanowire used for photoimmobilization reactions is easily recovered from water by decantation, showing the possible practical use for safe disposal of toxic cations in the environment.
Poul Norby - One of the best experts on this subject based on the ideXlab platform.
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syntheses structures and magnetic properties of nickel doped lepidocrocite Titanates
Inorganic Chemistry, 2009Co-Authors: Poul Norby, Hiroshi Okamoto, Helmer FjellvågAbstract:Ni-doped titanate CsxTi2−x/2Nix/2O4 and its protonic derivative HxTi2−x/2Nix/2O4·xH2O (x = 0.7) were synthesized and characterized by means of synchrotron X-ray diffraction, Raman scattering, X-ray photoelectron spectroscopy (XPS), and magnetic measurements. CsxTi2−x/2Nix/2O4 crystallizes in an orthorhombic structure (space group Immm), consisting of infinite two-dimensional (2D) host layers of the lepidocrocite (γ-FeOOH) type. The substitution of Ni atoms for Ti in the 2D octahedral layers results in negative charges that are compensated by interlayer Cs+ ions. Raman scattering and XPS indicate that local structural perturbations are induced upon exchange of interlayer Cs ions with protons H3O+. Magnetic measurements reveal typical paramagnetism induced by Ni substitution; the effective paramagnetic moment μeff = 1.57(1) μB and Curie−Weiss temperature −2.51(1) K are obtained for HxTi2−x/2Nix/2O4·xH2O. Ni- and Mg-codoped Titanates CsxTi2−x/2(NiyMg1−y)x/2O4 (x = 0.7, 0 ≤ y ≤ 1) were also reported. The crys...
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protonic titanate derived from csxti2 x 2mgx 2o4 x 0 7 with lepidocrocite type layered structure
Journal of Materials Chemistry, 2009Co-Authors: Helmer Fjellvåg, Poul NorbyAbstract:A layered titanate CsxTi2−x/2Mgx/2O4 (x = 0.7) with lepidocrocite (γ-FeOOH)-type layered structure was prepared via solid-state reaction. Extraction of both Mg2+ ions in the host layers and interlayer Cs+ ions was achieved during an acid-exchange process, producing a new protonic titanate HxTi2−x/2O4−x/2·H2O. This phase was distinguished from isomorphous related compounds in terms of removable lattice Mg and O atoms. The protonic titanate HxTi2−x/2O4−x/2·H2O showed excellent exfoliation/delamination reactivity upon intercalating organic amine ions as well as the ability to produce single two-dimensional titanate nanosheets with small thickness of about 1 nm. These findings offered a new clue for understanding the physicochemical properties of lattice dopants in lepidocrocite Titanates.
F C Walsh - One of the best experts on this subject based on the ideXlab platform.
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kinetics of alkali metal ion exchange into nanotubular and nanofibrous Titanates
Journal of Physical Chemistry C, 2007Co-Authors: Dmitry V Bavykin, F C WalshAbstract:The kinetics of intercalation of Li+, Na+, K+ and Cs+ cations between the layers of titanate nanotubes and nanofibres have been studied in an aqueous suspension of nanotubes at 25oC. The rate of intercalation was found to be similar for different cations and depended on the length of the nanotubes. The decrease in nanotube length resulted in a higher rate of ion-exchange, indicating that the transport of cations in titanate nanotubes occurred probably along their length. In contrast, the transport of cations in titanate nanofibres probably dominated in the direction perpendicular to length. Correlations between the rate of intercalation and the crystal structure modification following intercalation have been established for nanotubular and nanofibrous Titanates.
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protonated Titanates and tio2 nanostructured materials synthesis properties and applications
Advanced Materials, 2006Co-Authors: Dmitry V Bavykin, Jens M Friedrich, F C WalshAbstract:Tubular and fibrous nanostructures of Titanates have recently been synthesized and characterized. Three general approaches (template assisted, anodic oxidation, and alkaline hydrothermal) for the preparation of nanostructured titanate and TiO2 are reviewed. The crystal structures, morphologies, and mechanism of formation of nanostructured Titanates produced by the alkaline hydrothermal method are critically discussed. The physicochemical properties of nanostructured Titanates are highlighted and the links between properties and applications are emphasized. Examples of early applications of nanostructured Titanates in catalysis, photocatalysis, electrocatalysis, lithium batteries, hydrogen storage, and solar-cell technologies are reviewed. The stability of titanate nanotubes at elevated temperatures and in acid media is considered.
