Interconnected 3D Framework of CeO<sub>2</sub> with High Oxygen Storage Capacity: High-Resolution Scanning Electron Microscopic Observation

Lü, Jinfeng; Asahina, Shunsuke; Takami, Seiichi; Yoko, Akira; Seong, Gimyeong; Tomai, Takaaki; Adschiri, Tadafumi

doi:10.1021/acsanm.9b02446

Cited by 13 publications

(7 citation statements)

References 46 publications

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“…SBA-15 and mesoporous CeO 2 were synthesized using the following procedure [ 19 ]. First, 5.14 g of Pluronic P123 was dissolved in a mixture of 30.96 g of aqueous 37% HCl and water (144 g).…”

Section: Methodsmentioning

confidence: 99%

Direct Observation Techniques Using Scanning Electron Microscope for Hydrothermally Synthesized Nanocrystals and Nanoclusters

et al. 2021

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Metal oxide nanocrystals have garnered significant attention owing to their unique properties, including luminescence, ferroelectricity, and catalytic activity. Among the various synthetic methods, hydrothermal synthesis is a promising method for synthesizing metal oxide nanocrystals and nanoclusters. Because the shape and surface structure of the nanocrystals largely affect their properties, their analytical methods should be developed. Further, the arrangement of nanocrystals should be studied because the properties of nanoclusters largely depend on the arrangement of the primary nanocrystals. However, the analysis of nanocrystals and nanoclusters remains difficult because of their sizes. Conventionally, transmission electron microscopy (TEM) is widely used to study materials in nanoscale. However, TEM images are obtained as the projection of three-dimensional structures, and it is difficult to observe the surface structures and the arrangement of nanocrystals using TEM. On the other hand, scanning electron microscopy (SEM) relies on the signals from the surface of the samples. Therefore, SEM can visualize the surface structures of samples. Previously, the spatial resolution of SEM was not enough to observe nanoparticles and nanomaterials with sizes of between 10 and 50 nm. However, recent developments, including the low-landing electron-energy method, improved the spatial resolution of SEM, which allows us to observe fine details of the nanocluster surface directory. Additionally, improved detectors allow us to visualize the elemental mapping of materials even at low voltage with high solid angle. Further, the use of a liquid sample holder even enabled the observation of nanocrystals in water. In this paper, we discuss the development of SEM and related observation technologies through the observation of hydrothermally prepared nanocrystals and nanoclusters.

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Section: Methodsmentioning

confidence: 99%

Direct Observation Techniques Using Scanning Electron Microscope for Hydrothermally Synthesized Nanocrystals and Nanoclusters

et al. 2021

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“…CeO 2 is appealing because of its unique structure and intrinsic oxygen vacancy (V O ) defect, which can be rapidly formed and eliminated on the surface of CeO 2 , giving the redox cycle of Ce 4+ ⇔ Ce 3+ . This is the source of the oxygen storage capacity (OSC), which could be described by Reaction (1) and could also be written using Kroger and Vink notations as Reaction (2) [9]:…”

Section: Introductionmentioning

confidence: 99%

Novel Mesoporous and Multilayered Yb/N-Co-Doped CeO2 with Enhanced Oxygen Storage Capacity

Xu,

Gao,

et al. 2023

Materials

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A cubic fluorite-type CeO2 with mesoporous multilayered morphology was synthesized by the solvothermal method followed by calcination in air, and its oxygen storage capacity (OSC) was quantified by the amount of O2 consumption per gram of CeO2 based on hydrogen temperature programmed reduction (H2–TPR) measurements. Doping CeO2 with ytterbium (Yb) and nitrogen (N) ions proved to be an effective route to improving its OSC in this work. The OSC of undoped CeO2 was 0.115 mmol O2/g and reached as high as 0.222 mmol O2/g upon the addition of 5 mol.% Yb(NO3)3∙5H2O, further enhanced to 0.274 mmol O2/g with the introduction of 20 mol.% triethanolamine. Both the introductions of Yb cations and N anions into the CeO2 lattice were conducive to the formation of more non-stoichiometric oxygen vacancy (VO) defects and reducible–reoxidizable Cen+ ions. To determine the structure performance relationships, the partial least squares method was employed to construct two linear functions for the doping level vs. lattice parameter and [VO] vs. OSC/SBET.

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“…The filigree structures of mesoporous silica materials (MSMs), often exhibiting regularly arranged pores with typical diameters of 2–50 nm and numerous possible space group symmetries, are already intriguing by themselves. Nevertheless, mesoporous silica plays a key role in various applications, for example, as a support material in heterogeneous catalysis, − as a hard template, − for energy storage and conversion, − as a host matrix for dyes, , and for the delivery of biomedically active molecules. − …”

Section: Introductionmentioning

confidence: 99%

Mechanisms and Intermediates in the True Liquid Crystal Templating Synthesis of Mesoporous Silica Materials

et al. 2021

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Mesoporous silica materials (MSMs) produced by true liquid crystal templating (TLCT) are often considered as direct inverted replicas of the initial lyotropic liquid crystal (LLC) phase. However, the predictive design of tailor-made MSMs requires the full knowledge of the TLCT process, which is still incomplete. Here, we tackle this issue by monitoring the structural evolution during the templating process by small-angle X-ray scattering, showing that after the addition of the silica source the reaction mixture is first isotropic and then an intermediary liquid crystal phase appears, which is the key to the success of the templating process, namely the formation of ordered MSMs. We analyze the structure and the formation dynamics of this intermediary phase and present a simple theoretical model, which allows us to connect the structural parameters of the initial LLC and the MSM. These results provide an enhanced understanding of the TLCT process and are an important step toward the predictable synthesis of new MSMs in the future.

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Interconnected 3D Framework of CeO₂ with High Oxygen Storage Capacity: High-Resolution Scanning Electron Microscopic Observation

Cited by 13 publications

References 46 publications

Direct Observation Techniques Using Scanning Electron Microscope for Hydrothermally Synthesized Nanocrystals and Nanoclusters

Direct Observation Techniques Using Scanning Electron Microscope for Hydrothermally Synthesized Nanocrystals and Nanoclusters

Novel Mesoporous and Multilayered Yb/N-Co-Doped CeO2 with Enhanced Oxygen Storage Capacity

Mechanisms and Intermediates in the True Liquid Crystal Templating Synthesis of Mesoporous Silica Materials

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Interconnected 3D Framework of CeO2 with High Oxygen Storage Capacity: High-Resolution Scanning Electron Microscopic Observation

Cited by 13 publications

References 46 publications

Direct Observation Techniques Using Scanning Electron Microscope for Hydrothermally Synthesized Nanocrystals and Nanoclusters

Direct Observation Techniques Using Scanning Electron Microscope for Hydrothermally Synthesized Nanocrystals and Nanoclusters

Novel Mesoporous and Multilayered Yb/N-Co-Doped CeO2 with Enhanced Oxygen Storage Capacity

Mechanisms and Intermediates in the True Liquid Crystal Templating Synthesis of Mesoporous Silica Materials

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Interconnected 3D Framework of CeO₂ with High Oxygen Storage Capacity: High-Resolution Scanning Electron Microscopic Observation