scholarly journals Correction to “Chemical Potential of Metal Atoms in Supported Nanoparticles: Dependence upon Particle Size and Support”

ACS Catalysis ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 8763-8764
Author(s):  
Charles T. Campbell ◽  
Zhongtian Mao
Keyword(s):  
Particle Size ◽  
Chemical Potential ◽  
Supported Nanoparticles ◽  
Metal Atoms

Environment of Metal–O–Fe Bonds Enabling High Activity in CO2 Reduction on Single Metal Atoms and on Supported Nanoparticles

2021 ◽  
Vol 143 (14) ◽  
pp. 5540-5549
Author(s):  
Yifeng Zhu ◽  
Simuck F. Yuk ◽  
Jian Zheng ◽  
Manh-Thuong Nguyen ◽  
Mal-Soon Lee ◽  
...  
Keyword(s):  
High Activity ◽  
Co2 Reduction ◽  
Supported Nanoparticles ◽  
Metal Atoms

High Yield Synthesis of single crystal FCC Silver Nanoparticles and their Size Control

2007 ◽  
Vol 1056 ◽  
Author(s):  
Hiroyuki Nakamura ◽  
Toshiyuki Shimizu ◽  
Masato Uehara ◽  
Yoshiko Yamaguchi ◽  
Hideaki Maeda
Keyword(s):  
Particle Size ◽  
Silver Nanoparticles ◽  
Single Crystal ◽  
Ostwald Ripening ◽  
Chemical Potential ◽  
Size Control ◽  
Product Yield ◽  
High Yield ◽  
Face Centered Cubic ◽  
Chemical Potential Difference

ABSTRACTFace centered cubic (FCC) single crystal silver nanoparticles(NPs) of nearly monodispersed particle size of 12nm were prepared by simple ripening multi-twined particles (MTP). The product yield was nearly 100% and growth mechanism was considered to be similar to Ostwald ripening but utilize chemical potential difference between MTP and FCC NPs. Controlling the ratio between defectless and defective particles before ripening by controlling kinetics of particle generation stage, it was possible to control the final defectless particle size from 7-18 nm maintaining almost 100% product yield.

scholarly journals Electrochemical top-down synthesis of C-supported Pt nano-particles with controllable shape and size: Mechanistic insights and application

Nano Research ◽  
2020 ◽  
Author(s):  
Batyr Garlyyev ◽  
Sebastian Watzele ◽  
Johannes Fichtner ◽  
Jan Michalička ◽  
Alexander Schökel ◽  
...  
Keyword(s):  
Particle Size ◽  
State Of The Art ◽  
Reduction Reaction ◽  
Nano Particles ◽  
Size Distributions ◽  
Top Down ◽  
Supported Nanoparticles ◽  
Mass Activity ◽  
Potential Frequency ◽  
Alternating Voltage

AbstractIn this work, we demonstrate the power of a simple top-down electrochemical erosion approach to obtain Pt nanoparticle with controlled shapes and sizes (in the range from ∼ 2 to ∼ 10 nm). Carbon supported nanoparticles with narrow size distributions have been synthesized by applying an alternating voltage to macroscopic bulk platinum structures, such as disks or wires. Without using any surfactants, the size and shape of the particles can be changed by adjusting simple parameters such as the applied potential, frequency and electrolyte composition. For instance, application of a sinusoidal AC voltage with lower frequencies results in cubic nanoparticles; whereas higher frequencies lead to predominantly spherical nanoparticles. On the other hand, the amplitude of the sinusoidal signal was found to affect the particle size; the lower the amplitude of the applied AC signal, the smaller the resulting particle size. Pt/C catalysts prepared by this approach showed 0.76 A/mg mass activity towards the oxygen reduction reaction which is ∼ 2 times higher than the state-of-the-art commercial Pt/C catalyst (0.42 A/mg) from Tanaka. In addition to this, we discussed the mechanistic insights about the nanoparticle formation pathways.

Microstructural characterization of laser-melted/roller-quenched dicalcium silicate

1988 ◽  
Vol 46 ◽  
pp. 582-583
Author(s):  
C. J. Chan ◽  
K. R. Venkatachari ◽  
W. M. Kriven ◽  
J. F. Young
Keyword(s):  
Particle Size ◽  
Raw Materials ◽  
Shape Change ◽  
Microstructural Characterization ◽  
Particle Size Effect ◽  
Dicalcium Silicate ◽  
Laser Melting ◽  
Uniform Size ◽  
Cell Shape Change ◽  
Wide Range

Dicalcium silicate (Ca2SiO4) is a major component of Portland cement. It has also been investigated as a potential transformation toughener alternative to zirconia. It has five polymorphs: α, α'H, α'L, β and γ. Of interest is the β-to-γ transformation on cooling at about 490°C. This transformation, accompanied by a 12% volume increase and a 4.6° unit cell shape change, is analogous to the tetragonal-to-monoclinic transformation in zirconia. Due to the processing methods used, previous studies into the particle size effect were limited by a wide range of particle size distribution. In an attempt to obtain a more uniform size, a fast quench rate involving a laser-melting/roller-quenching technique was investigated.The laser-melting/roller-quenching experiment used precompacted bars of stoichiometric γ-Ca2SiO4 powder, which were synthesized from AR grade CaCO3 and SiO2xH2O. The raw materials were mixed by conventional ceramic processing techniques, and sintered at 1450°C. The dusted γ-Ca2SiO4 powder was uniaxially pressed into 0.4 cm x 0.4 cm x 4 cm bars under 34 MPa and cold isostatically pressed under 172 MPa. The γ-Ca2SiO4 bars were melted by a 10 KW-CO2 laser.

Incommensurate modulated phases of the NbxTa1-xTe4 charge density wave system

1992 ◽  
Vol 50 (1) ◽  
pp. 58-59
Author(s):  
S. Ritchie ◽  
J. C. Bennett ◽  
A. Prodan ◽  
F.W. Boswell ◽  
J.M. Corbett
Keyword(s):  
Charge Density ◽  
Charge Density Wave ◽  
Direct Evidence ◽  
Density Wave ◽  
Wave System ◽  
Modulated Phases ◽  
Metal Atoms ◽  
Incommensurate Modulation ◽  
End Members ◽  
Modulation Wave Vector

A continuous sequence of compounds having composition NbxTa1-xTe4; 0 ≤ x ≤ 1 have been studied by electron diffraction and microscopy. Previous studies have shown that the end members of the series, TaTε4 and NbTε4 possess a quasi-one-dimensional character and exhibit charge density wave (CDW) distortions. In these compounds, the subcell structure is tetragonal with axes (a × a × c) and consists of the metal atoms (Nb or Ta) centered within an extended antiprismatic cage of Te atoms. At room temperature, TaTε4 has a commensurate modulation structure with a 2a × 2a × 3c unit cell. In NbTε4, an incommensurate modulation with × ∼ 16c axes is observed. Preliminary studies of the mixed compounds NbxTα1-xTε4 showed a discontinuous jump of the modulation wave vector commensurate to incommensurate when the Nb dopant concentration x, exceeded x ≃ 0.3, In this paper, the nature of the compositional dependence of is studied in greater detail and evidence is presented for a stepwise variation of . This constitutes the first direct evidence for a Devil's staircase in CDW materials.

Analytical Electron Microscopy study of two vehicle-aged automotive exhaust catalysts having dissimilar activities

1989 ◽  
Vol 47 ◽  
pp. 272-273
Author(s):  
Sooho Kim ◽  
M. J. D’Aniello
Keyword(s):  
Electron Microscopy ◽  
Particle Size ◽  
Noble Metal ◽  
Catalyst Deactivation ◽  
Analytical Electron Microscopy ◽  
Microscopy Study ◽  
Metal Particles ◽  
Automotive Exhaust ◽  
Exhaust Catalysts ◽  
Analytical Electron

Automotive catalysts generally lose-agtivity during vehicle operation due to several well-known deactivation mechanisms. To gain a more fundamental understanding of catalyst deactivation, the microscopic details of fresh and vehicle-aged commercial pelleted automotive exhaust catalysts containing Pt, Pd and Rh were studied by employing Analytical Electron Microscopy (AEM). Two different vehicle-aged samples containing similar poison levels but having different catalytic activities (denoted better and poorer) were selected for this study.The general microstructure of the supports and the noble metal particles of the two catalysts looks similar; the noble metal particles were generally found to be spherical and often faceted. However, the average noble metal particle size on the poorer catalyst (21 nm) was larger than that on the better catalyst (16 nm). These sizes represent a significant increase over that found on the fresh catalyst (8 nm). The activity of these catalysts decreases as the observed particle size increases.

Sign in / Sign up

Export Citation Format

Share Document