A feasible strategy to balance the crystallinity and specific surface area of metal oxide nanocrystals

In this paper, the features of obtaining a Co-Mo/Al2O3 catalyst to synthesize carbon nanotubes (CNTs) by thermal decomposition were studied. It was revealed that the duration of the pre-catalyst thermal decomposition stage in the process of developing a metal oxide system has a significant impact on its activity in the synthesis of carbon nanostructured materials by chemical vapor deposition (CVD). It was proved that an effective catalyst for CNTs synthesis can be obtained by through thermal decomposition of the pre – catalyst, without calcination of the metal oxide system. The use of the Co-Mo/Al2O3 catalyst, synthesized in such a way, in the CVD process makes it possible to reduce the cost of synthesized CNTs. Using scanning electron microscopy, it was shown that the size of the grains, and specific surface area of the formed Co-Mo/Al2O3 catalyst depend on the thermal treatment conditions of the pre-catalyst. Under the conditions for the implementation of the pre-catalyst thermal decomposition stage (temperature, volume, duration, etc.), it is possible to contro not only the characteristics of the resulting catalyst (specific surface area, efficiency), but also the characteristics of the CNTs (diameter, degree of defectiveness). In the course of experiments, the optimal modes of implementation of the method for obtaining the Co-Mo/Al2O3 catalyst allowed forming a system with a specific surface area of ~ 108 m2/g. The use of the resulting catalyst in the synthesis of nanostructured materials provides a high specific yield of multi-walled CNTs with a diameter of 8-20 nm and a degree of defectiveness of 0.97.

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Simultaneous deposition of Au nanoparticles during flame synthesis of TiO2 and SiO2

Journal of Materials Research ◽

10.1557/jmr.2003.0017 ◽

2003 ◽

Vol 18 (1) ◽

pp. 115-120 ◽

Cited By ~ 61

Author(s):

L. Mädler ◽

W. J. Stark ◽

S. E. Pratsinis

Keyword(s):

Metal Oxide ◽

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Au Nanoparticles ◽

Visible Region ◽

Gold Deposits ◽

Absorption Bands ◽

Oxide Support ◽

Metal Oxide Support

Nanostructured gold/titania and gold/silica particles with up to 4 wt% Au were made by a single-step process in a spray flame reactor. Gold(III)-chloride hydrate and titania- or silica-based metalorganic precursors were mixed in a liquid fuel solution, keeping concentrations in the flame and overall combustion enthalpy constant. The powders were characterized by x-ray diffraction, transmission electron microscopy, Brunauer–Emmett–Teller, and ultraviolet–visible analysis. The titania or silica specific surface area and the crystalline structure of titania were not affected by the presence of gold in the flame. Furthermore the size of the gold deposits was independent of the metal oxide support (TiO2 or SiO2) and its specific surface area (100 and 320 m2/g, respectively). The gold nanoparticles were nonagglomerated, spherical, mostly single crystalline, and well dispersed on the metal oxide support. Depending on the Au weight fraction (1, 2, and 4 wt%) the Au nanoparticles' mass mean diameter was 3, 7, and 15 nm, respectively, on both titania and silica. The particles showed surface plasmon absorption bands in the ultraviolet–visible region, which is typical for nano-sized gold. This absorption band was red shifted in the case of the titania support, while no shift occurred with the silica support.

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Synthesis of high-specific-surface-area Li-Al mixed metal oxide: Through nanoseed-assisted growth of layered double hydroxide

Applied Clay Science ◽

10.1016/j.clay.2021.106006 ◽

2021 ◽

Vol 203 ◽

pp. 106006

Author(s):

Masanori Takemoto ◽

Yasuaki Tokudome ◽

Hidenobu Murata ◽

Kenji Okada ◽

Masahide Takahashi ◽

...

Keyword(s):

Metal Oxide ◽

Specific Surface ◽

Surface Area ◽

Layered Double Hydroxide ◽

Specific Surface Area ◽

High Specific Surface Area ◽

Mixed Metal Oxide ◽

Mixed Metal ◽

Double Hydroxide

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Characterization of Commercial Metal Oxide Nanomaterials: Crystalline Phase, Particle Size and Specific Surface Area

Nanomaterials ◽

10.3390/nano10091812 ◽

2020 ◽

Vol 10 (9) ◽

pp. 1812

Author(s):

Michael Bushell ◽

Suzanne Beauchemin ◽

Filip Kunc ◽

David Gardner ◽

Jeffrey Ovens ◽

...

Keyword(s):

Particle Size ◽

Metal Oxide ◽

Specific Surface ◽

Human Health ◽

Surface Area ◽

Specific Surface Area ◽

Crystalline Phase ◽

Size Distributions ◽

Metal Oxide Nanomaterials

Physical chemical characterization of nanomaterials is critical to assessing quality control during production, evaluating the impact of material properties on human health and the environment, and developing regulatory frameworks for their use. We have investigated a set of 29 nanomaterials from four metal oxide families (aluminum, copper, titanium and zinc) with a focus on the measurands that are important for the basic characterization of dry nanomaterials and the determination of the dose metrics for nanotoxicology. These include crystalline phase and crystallite size, measured by powder X-ray diffraction, particle shape and size distributions from transmission electron microscopy, and specific surface area, measured by gas adsorption. The results are compared to the nominal data provided by the manufacturer, where available. While the crystalline phase data are generally reliable, data on minor components that may impact toxicity is often lacking. The crystal and particle size data highlight the issues in obtaining size measurements of materials with broad size distributions and significant levels of aggregation, and indicate that reliance on nominal values provided by the manufacturer is frequently inadequate for toxicological studies aimed at identifying differences between nanoforms. The data will be used for the development of models and strategies for grouping and read-across to support regulatory human health and environmental assessments of metal oxide nanomaterials.

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Enhancement of photocatalytic NOx abatement on titania via additional metal oxide NOx-storage domains: Interplay between surface acidity, specific surface area, and humidity

Applied Catalysis B Environmental ◽

10.1016/j.apcatb.2019.118227 ◽

2020 ◽

Vol 263 ◽

pp. 118227 ◽

Cited By ~ 2

Author(s):

Mustafa Çağlayan ◽

Muhammad Irfan ◽

Kerem Emre Ercan ◽

Yusuf Kocak ◽

Emrah Ozensoy

Keyword(s):

Metal Oxide ◽

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Surface Acidity ◽

Nox Storage ◽

Nox Abatement

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Mixed Metal Oxide by Calcination of Layered Double Hydroxide: Parameters Affecting Specific Surface Area

Nanomaterials ◽

10.3390/nano11051153 ◽

2021 ◽

Vol 11 (5) ◽

pp. 1153

Author(s):

Su-Bin Lee ◽

Eun-Hye Ko ◽

Joo Y. Park ◽

Jae-Min Oh

Keyword(s):

Metal Oxide ◽

Specific Surface ◽

Surface Area ◽

Calcination Temperature ◽

Layered Double Hydroxide ◽

Specific Surface Area ◽

High Performance ◽

Mixed Metal Oxide ◽

Mixed Metal ◽

Double Hydroxide

Mixed metal oxide (MMO) is one of the widely utilized ceramic materials in various industries. In order to obtain high performance, the specific surface area of MMO should be controlled. Calcination of layered double hydroxide (LDH) is a versatile way to prepare MMO with homogeneous metal distribution and well-developed porosity. Although researchers found that the specific surface area of LDH-originated MMO was relatively high, it had not been systematically investigated how the surface area is controlled under a certain parameter. In this review, we summarized LDH-originated MMO with various starting composition, calcination temperature, and pore developing agent in terms of specific surface area and porosity. Briefly, it was represented that MMOs with Mg-Al components generally had higher specific surface area than Mg-Fe or Zn-Al components. Calcination temperature in the range 300–600 °C resulted in the high specific surface area, while upper or lower temperature reduced the values. Pore developing agent did not result in dramatic increase in MMO; however, the pore size distribution became narrower in the presence of pore developing agents.

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