Spreading and Wetting

Knzinger, H.; Taglauer, E.

doi:10.1002/9783527619528.ch4h

Cited by 12 publications

(5 citation statements)

References 87 publications

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“…Considering the relatively low melting point of BiVO 4 (934 °C), the formation of larger particles at high T f can be attributed to sintering of the collected particles on the filter. The Tammann temperature for BiVO 4 can be estimated to be around 300 °C . This, together with associated phase transitions around 300 °C as discussed in the next section, explains the sintering of particles into larger ones at T f > 300 °C.…”

Section: Resultsmentioning

confidence: 97%

Brilliant Yellow, Transparent Pure, and SiO₂-Coated BiVO₄ Nanoparticles Made in Flames

2008

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Transparent, yellow bismuth vanadate nanoparticles were made by flame spray pyrolysis. These materials are of special interest as brilliant yellow pigments. The structural properties of the as-prepared powders were characterized by X-ray diffraction, Raman spectroscopy, nitrogen adsorption, transmission electron microscopy, zeta potential measurements, and photospectroscopy. Depending on the particle collection temperature, either pale, amorphous materials or brilliant yellow-green, crystalline BiVO4 with particle size of about 50 nm were formed by direct calcination above 300 °C. The addition of Si during flame synthesis of BiVO4 resulted in smaller such crystals of about 20 nm that were embedded in silica. This prevented sintering of the BiVO4 particles during calcination at 400 °C and resulted in thermally stable, highly transparent, yellow particles.

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Section: Resultsmentioning

confidence: 97%

Brilliant Yellow, Transparent Pure, and SiO₂-Coated BiVO₄ Nanoparticles Made in Flames

2008

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“…With increase in temperature, a higher mobility of the metal particles appears. Generally, the mobility of the metal particles is related to its Tammann temperature, i.e., the temperature corresponding to half of the melting point of the bulk . For instance, the Tammann temperature for Ni and Ni−Cu (1:1) is 863 and ∼766 K, respectively.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Platelet Carbon Nanofiber/Carbon Felt Composite on in Situ Generated Ni−Cu Nanoparticles

Zhao

Kvande

et al. 2010

J. Phys. Chem. C

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A platelet carbon nanofiber/carbon felt composite with a high surface area (>250 m 2 /g) is synthesized over a carbon felt supported Ni-Cu catalyst using ethane-hydrogen mixtures at 923 K. A uniform layer of carbon nanofibers is thus achieved via an in situ generation and dispersion of Ni-Cu nanoparticles induced by the surface reaction of hydrocarbon decomposition. This represents a cost-effective and flexible method without the requirement for presynthesis of uniformly distributed nanoparticles. Both thermodynamic analysis and experimental observation reveal that, in the initial growth period, formation of a molten phase of the nanosized Ni-Cu-C phase promotes the fragmentation of Ni-Cu parent particles of micrometer size. A unique octopuslike growth mode is observed during the formation of graphene layers from this liquid-like Ni-Cu-C system. A comparative study between Ni and Ni-Cu catalysts is performed. It is found that the addition of Cu in the Ni-Cu catalysts can enhance the fragmentation ability of the parent Ni-Cu particles when contacting with hydrocarbon. A treelike growth mode of carbon nanofibers grown on Ni-Cu catalysts is observed due to the further fragmentation of Ni-Cu particles during carbon nanofiber growth. In contrast to Ni-Cu catalysts, two different growth mechanisms on the Ni catalyst are found: a governing tip-growth mechanism by particles smaller than 50 nm and an octopus-like growth mechanism by larger particles (50-100 nm). The graphene sheet orientation in the carbon nanofibers depends on the composition of the metal particle; fishbone carbon nanofibers are obtained with carbon felt supported Ni catalysts, while platelet carbon nanofibers were obtained with Ni-Cu catalysts. The formation of platelet carbon nanofibers from the Ni-Cu catalysts is ascribed to a higher degree of interface wetting between the Ni-Cu particle and the produced graphene sheets.

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“…The preferential anchoring of WO x on TiO x is related to the higher surface free energy of titania relative to silica, and the facile surface diffusion of surface WO x at modest temperatures. The thermodynamic driving force is lowering of the system surface free energy (replacing higher free energy surface Ti−OH bonds with lower surface free energy terminal WO bonds) and the kinetics are facilitated by surface diffusion of the metal oxides (related to the modest WO 3 Tammann temperature , ). Thus, both location and structure of surface WO x species are controlled by the titania nanoligands and the surface WO x structure is independent of titania loading.…”

Section: Resultsmentioning

confidence: 99%

Tuning the Electronic and Molecular Structures of Catalytic Active Sites with Titania Nanoligands

et al. 2008

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A series of supported 1-60% TiO(2)/SiO(2) catalysts were synthesized and subsequently used to anchor surface VO(x) redox and surface WO(x) acid sites. The supported TiO(x), VO(x), and WO(x) phases were physically characterized with TEM, in situ Raman and UV-vis spectroscopy, and chemically probed with in situ CH(3)OH-IR, CH(3)OH-TPSR and steady-state CH(3)OH dehydration. The CH(3)OH chemical probe studies revealed that the surface VO(x) sites are redox in nature and the surface WO(x) sites contain acidic character. The specific catalytic activity of surface redox (VO(4)) and acidic (WO(5)) sites coordinated to the titania nanoligands are extremely sensitive to the degree of electron delocalization of the titania nanoligands. With decreasing titania domain size, <10 nm, acidic activity increases and redox activity decreases due to their inverse electronic requirements. This is the first systematic study to demonstrate the ability of oxide nanoligands to tune the electronic structure and reactivity of surface metal oxide catalytic active sites.

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Spreading and Wetting

Cited by 12 publications

References 87 publications

Brilliant Yellow, Transparent Pure, and SiO₂-Coated BiVO₄ Nanoparticles Made in Flames

Brilliant Yellow, Transparent Pure, and SiO₂-Coated BiVO₄ Nanoparticles Made in Flames

Synthesis of Platelet Carbon Nanofiber/Carbon Felt Composite on in Situ Generated Ni−Cu Nanoparticles

Tuning the Electronic and Molecular Structures of Catalytic Active Sites with Titania Nanoligands

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Spreading and Wetting

Cited by 12 publications

References 87 publications

Brilliant Yellow, Transparent Pure, and SiO2-Coated BiVO4 Nanoparticles Made in Flames

Brilliant Yellow, Transparent Pure, and SiO2-Coated BiVO4 Nanoparticles Made in Flames

Synthesis of Platelet Carbon Nanofiber/Carbon Felt Composite on in Situ Generated Ni−Cu Nanoparticles

Tuning the Electronic and Molecular Structures of Catalytic Active Sites with Titania Nanoligands

Contact Info

Product

Resources

About

Brilliant Yellow, Transparent Pure, and SiO₂-Coated BiVO₄ Nanoparticles Made in Flames

Brilliant Yellow, Transparent Pure, and SiO₂-Coated BiVO₄ Nanoparticles Made in Flames