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

2003 ◽  
Vol 18 (1) ◽  
pp. 115-120 ◽  
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.

scholarly journals Features of obtaining the catalyst for the synthesis of carbon nanotubes

2019 ◽  
Vol 81 (2) ◽  
pp. 261-267 ◽  
Author(s):  
E. A. Burakova ◽  
G. S. Besperstova ◽  
M. A. Neverova ◽  
A. G. Tkachev ◽  
N. V. Orlova ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Thermal Decomposition ◽  
Metal Oxide ◽  
Specific Surface ◽  
Surface Area ◽  
Nanostructured Materials ◽  
Specific Surface Area ◽  
Oxide System ◽  
Decomposition Stage ◽  
Al2o3 Catalyst

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.

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

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

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

Nanomaterials ◽  
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.

scholarly journals Nanoscale Multidimensional Pd/TiO2/g-C3N4 Catalyst for Efficient Solar-Driven Photocatalytic Hydrogen Production

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 59
Author(s):  
Ting-Han Lin ◽  
Yin-Hsuan Chang ◽  
Kuo-Ping Chiang ◽  
Jer-Chyi Wang ◽  
Ming-Chung Wu
Keyword(s):  
Hydrogen Production ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Visible Region ◽  
Green Energy ◽  
Solar Irradiation ◽  
Xenon Lamp ◽  
Tio2 Nanofibers ◽  
Photocatalytic Hydrogen Production

Solar-to-fuel conversion is an innovative concept for green energy, attracting many researchers to explore them. Solar-driven photocatalysts have become an essential solution to provide valuable chemicals like hydrogen, hydrocarbon, and ammonia. For sustainable stability under solar irradiation, titanium dioxide is regarded as an acceptable candidate, further showing excellent photocatalytic activity. Incorporating the photo-sensitizers, including noble metal nanoparticles and polymeric carbon-based material, can improve its photoresponse and facilitate the electron transfer and collection. In this study, we synthesized the graphitic carbon nitride (g-C3N4) nanosheet incorporated with high crystalline TiO2 nanofibers (NF) as 1D/2D heterostructure catalyst for photocatalytic water splitting. The microstructure, optical absorption, crystal structure, charge carrier dynamics, and specific surface area were characterized systematically. The low bandgap of 2D g-C3N4 nanosheets (NS) as a sensitizer improves the specific surface area and photo-response in the visible region as the incorporated amount increases. Because of the band structure difference between TiO2 and g-C3N4, constructing the heterojunction formation, the superior separation of electron-hole is observed. The detection of reactive oxygen species and photo-assisted Kelvin probe microscopy are conducted to investigates the possible charge migration. The highest photocatalytic hydrogen production rate of Pd/TiO2/g-C3N4 achieves 11.62 mmol·h−1·g−1 under xenon lamp irradiation.

scholarly journals Characterization and photocatalytic activity of ZnO nanoflowers synthesized using Bridelia retusa leaf extract

2021 ◽  
Author(s):  
Ramesh Vinayagam ◽  
Shraddha Pai ◽  
Thivaharan Varadavenkatesan ◽  
Arivalagan Pugazhendhi ◽  
Raja Selvaraj
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Leaf Extract ◽  
Solar Irradiation ◽  
Bandgap Energy ◽  
Absorption Bands ◽  
First Order Kinetics ◽  
Bet Analysis ◽  
Bridelia Retusa

AbstractIn the current work, the leaf extract of Bridelia retusa was used for the first time to synthesize zinc oxide nanoparticles (ZnONPs). A zinc nanoparticle-specific 364-nm peak was discerned via UV–Vis studies with a typical bandgap energy of 3.41 eV. FE-SEM micrographs revealed flower-shaped structure of the ZnONPs. EDS analysis corroborated the presence of zinc and oxygen. XRD spectrum established the wurtzite structure, sized at 11.06 nm. The mesoporous texture (4.89 nm) of the nanoparticles was deduced from BET analysis, proving a higher specific surface area than commercial ZnONPs. FTIR spectroscopy resulted in absorption bands typical for ZnONPs. Within a span of 165 min, under solar irradiation, the ZnONPs facilitated the photocatalytic degradation of Rhodamine B dye upto 94.74%. Exhibiting pseudo-first-order kinetics, the process had a degradation constant of 0.0109 min−1. It was concluded that numerous factors led to the high degradation efficiency. High values of bandgap energy and specific surface area, along with the mesoporous and crystalline nature of the ZnONPs led to the observed effect. The ZnONPs were also stabilized by the phytochemicals in the B. retusa leaves. The study is thus able to successfully demonstrate the huge potential in the field of environmental nanoremediation. The viability of using ZnONPs as solar photocatalysts for treating dye-laden industrial wastewater was thus attested.

scholarly journals Synthesis and Characterization of Mn–C–CodopedTiO2Nanoparticles and Photocatalytic Degradation of Methyl Orange Dye under Sunlight Irradiation

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Wei Xin ◽  
Duanwei Zhu ◽  
Guanglong Liu ◽  
Yumei Hua ◽  
Wenbing Zhou
Keyword(s):  
Particle Size ◽  
Methyl Orange ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Visible Region ◽  
High Specific Surface Area ◽  
Size Analysis ◽  
Manganese Acetate ◽  
Sunlight Irradiation

Novel visible-light-active Mn–C–TiO2nanoparticles were synthesized by modified sol-gel method based on the self-assembly technique using polyoxyethylenes orbitan monooleate (Tween 80) as template and carbon precursor and manganese acetate as manganese precursor. The samples were characterized by XRD, FTIR, UV-vis diffuse reflectance, XPS, and laser particle size analysis. The XRD results showed that Mn–C–TiO2sample exhibited anatase phase and no other crystal phase was identified. High specific surface area, small crystallite size, and small particle size distribution could be obtained by manganese and carbon codoped and Mn–C–TiO2exhibited greater red shift in absorption edge of samples in visible region than that of C–TiO2and pure TiO2. The photocatalytic activity of synthesized catalyst was evaluated by photocatalytic oxidation of methyl orange (MO) solution under the sunlight irradiation. The results showed that Mn–C–TiO2nanoparticles have higher activity than other samples under sunlight, which could be attributed to the high specific surface area, smaller particle size, and lower band gap energy.

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

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Q. P. Zhang ◽  
X. N. Xu ◽  
Y. T. Liu ◽  
M. Xu ◽  
S. H. Deng ◽  
...  
Keyword(s):  
Metal Oxide ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area

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

Nanomaterials ◽  
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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