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Thermal-resist hydro-charged air filters (HCAFs) with charge stability for long-term efficient fine particle removal. Sep Purif Technol 2022. [DOI: 10.1016/j.seppur.2022.122236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Koo JJ, Jung KH, Park K, Min WJ, Yu KS, Kim ZH, Lee JK. Characterization of the Interfacial Structures of Core/Shell CdSe/ZnS QDs. J Phys Chem Lett 2022; 13:7220-7227. [PMID: 35912964 DOI: 10.1021/acs.jpclett.2c01923] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Core/shell quantum dots (QDs) have been extensively studied, yet their optical properties widely vary among studies. Such variation may arise from the variation in interfacial structures induced by the subtle difference in each synthetic procedure. Here, we studied the interfacial structures of CdSe/ZnS QDs using the time-of-flight medium energy ion-scattering spectroscopy (TOF-MEIS), which offers the radial elemental distributions as well as the overall elemental compositions of QDs. The TOF-MEIS spectra provided strong evidence for the existence of an alloyed layer at the interface between CdSe and ZnS in typical CdSe/ZnS QDs. On the basis of the emission and absorption spectra of QDs sampled during the synthesis, we conclude that such interfacial alloying is caused by the dissolution of CdSe seeds during the synthesis steps. Such a dissolution mechanism is further corroborated by the observation that the ligand environment of solvent (X or L type) leads to different shapes of interfaces.
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Affiliation(s)
- Ja-Jung Koo
- Department of Chemistry, Seoul National University, Seoul 08826, Republic of Korea
| | - Kwang Hwan Jung
- K-MAC, Yongsan-Dong 554, Yueseong-Gu, Daejeon 305-500, Republic of Korea
- R&D Center, NEOTOP Co., Ltd., Hwaseong-si, Gyeonggi-do 18468, Republic of Korea
| | - Kyungsu Park
- K-MAC, Yongsan-Dong 554, Yueseong-Gu, Daejeon 305-500, Republic of Korea
- HB Solution, Asan-si, Choongcheongnam-do 31413, Republic of Korea
| | - Won Ja Min
- K-MAC, Yongsan-Dong 554, Yueseong-Gu, Daejeon 305-500, Republic of Korea
- HB Solution, Asan-si, Choongcheongnam-do 31413, Republic of Korea
| | - Kyu-Sang Yu
- K-MAC, Yongsan-Dong 554, Yueseong-Gu, Daejeon 305-500, Republic of Korea
- HB Solution, Asan-si, Choongcheongnam-do 31413, Republic of Korea
| | - Zee Hwan Kim
- Department of Chemistry, Seoul National University, Seoul 08826, Republic of Korea
| | - Jin-Kyu Lee
- Department of Chemistry, Seoul National University, Seoul 08826, Republic of Korea
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3
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Temporal Growth and Aging of ZnO Nanoparticles in Colloidal Solution: Phase Field Model. J CLUST SCI 2022. [DOI: 10.1007/s10876-022-02309-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Zhang X, Wang Y, Liu W, Jin X. Needle-punched electret air filters (NEAFs) with high filtration efficiency, low filtration resistance, and superior dust holding capacity. Sep Purif Technol 2022. [DOI: 10.1016/j.seppur.2021.120146] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Nucleation/growth of the platinum nanoparticles under the liquid phase synthesis. Colloids Surf A Physicochem Eng Asp 2021. [DOI: 10.1016/j.colsurfa.2021.127525] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Handwerk DR, Shipman PD, Özkar S, Finke RG. Dust Effects on Ir(0) n Nanoparticle Formation Nucleation and Growth Kinetics and Particle Size-Distributions: Analysis by and Insights from Mechanism-Enabled Population Balance Modeling. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:1496-1506. [PMID: 32011887 DOI: 10.1021/acs.langmuir.9b03193] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The effects of microfiltration removal of filterable dust on nanoparticle formation kinetics and particle-size distribution, in a polyoxometalate polyanion (P2W15Nb3O629-)-stabilized Ir(0)n nanoparticle formation system, are analyzed by the newly developed method of Mechanism-Enabled Population Balance Modeling (ME-PBM). The [(Bu4N)5Na3(1,5-COD)Ir·P2W15Nb3O62] precatalyst system produces on average Ir(0)∼200 nanoparticles of 1.74 ± 0.33 nm and hence a particle-size distribution (PSD) of ±19% dispersion when the precatalyst is reduced under H2 in unfiltered propylene carbonate solvent. But if the precatalyst is reduced in microfiltered solvent and microfiltered reagent solutions (where the filtered solvent is then also used to rinse dust from the glassware), then larger Ir(0)∼300 1.96 ± 0.16 nm nanoparticles are produced with a remarkable, 2.4-fold lowered ±8% dispersion. The results and effects of the microfiltration reduction of dust are analyzed by the newly developed method of ME-PBM. More specifically, the studies reported herein address eight outstanding questions that are listed in the Introduction. Those questions include: how easy or difficult it is to fit PSD data? What is the ability of the recently discovered alternative termolecular nucleation and two size-dependent growth steps mechanism to account for the effects of dust on the PSD? What types and amount of PSD kinetics data are needed to deconvolute the PSD into the parameters of the ME-PBM? What is the reliability of the resulting rate constants? Additional questions addressed include: if the ME-PBM results offer insights into the remarkable 2.4-fold narrowing of the PSD post simple microfiltration lowering of the dust, and if the results are likely to be more general? The Summary and Conclusions section lists nine specific insights that include comments on needed future studies.
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Affiliation(s)
- Derek R Handwerk
- Department of Mathematics , Colorado State University , Fort Collins , Colorado 80523-1874 , United States
| | | | - Saim Özkar
- Department of Chemistry , Middle East Technical University , 06800 Ankara , Turkey
| | - Richard G Finke
- Department of Chemistry , Colorado State University , Fort Collins , Colorado 80523 , United States
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Design and synthesis of multigrain nanocrystals via geometric misfit strain. Nature 2020; 577:359-363. [PMID: 31942056 DOI: 10.1038/s41586-019-1899-3] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 10/30/2019] [Indexed: 11/08/2022]
Abstract
The impact of topological defects associated with grain boundaries (GB defects) on the electrical, optical, magnetic, mechanical and chemical properties of nanocrystalline materials1,2 is well known. However, elucidating this influence experimentally is difficult because grains typically exhibit a large range of sizes, shapes and random relative orientations3-5. Here we demonstrate that precise control of the heteroepitaxy of colloidal polyhedral nanocrystals enables ordered grain growth and can thereby produce material samples with uniform GB defects. We illustrate our approach with a multigrain nanocrystal comprising a Co3O4 nanocube core that carries a Mn3O4 shell on each facet. The individual shells are symmetry-related interconnected grains6, and the large geometric misfit between adjacent tetragonal Mn3O4 grains results in tilt boundaries at the sharp edges of the Co3O4 nanocube core that join via disclinations. We identify four design principles that govern the production of these highly ordered multigrain nanostructures. First, the shape of the substrate nanocrystal must guide the crystallographic orientation of the overgrowth phase7. Second, the size of the substrate must be smaller than the characteristic distance between the dislocations. Third, the incompatible symmetry between the overgrowth phase and the substrate increases the geometric misfit strain between the grains. Fourth, for GB formation under near-equilibrium conditions, the surface energy of the shell needs to be balanced by the increasing elastic energy through ligand passivation8-10. With these principles, we can produce a range of multigrain nanocrystals containing distinct GB defects.
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Faghihi N, Mkhonta S, Elder K, Grant M. Phase-field crystal for an antiferromagnet with elastic interactions. Phys Rev E 2019; 100:022128. [PMID: 31574615 DOI: 10.1103/physreve.100.022128] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Indexed: 11/07/2022]
Abstract
We introduce a model which contains the essential elements to formulate and study antiferromagnetism, using the phase-field crystal framework. We focus on the question of how magneto-elastic coupling could lift the frustration in the two-dimensional hexagonal antiferromagnetic phase. Using simulations we observe a rich variety of different phases stable in this model. To characterize different phases we calculate the chiral order parameter and identify the scaling behavior of this order parameter. Furthermore, we observe that vortices appear and are stable close to the nonmagnetic defects. Finally, we studied the ferrimagnetic and spin-flop phase transition in the presence of an external magnetic field.
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Affiliation(s)
- Niloufar Faghihi
- Physics Department, Rutherford Building, 3600 rue University, McGill University, Montréal, Québec, Canada H3A 2T8
| | - Simiso Mkhonta
- Department of Physics, University of Swaziland, Private Bag 4, Kwaluseni M201, Swaziland
| | - Ken Elder
- Department of Physics, Oakland University, Rochester, Michigan 48309, USA
| | - Martin Grant
- Physics Department, Rutherford Building, 3600 rue University, McGill University, Montréal, Québec, Canada H3A 2T8
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Geonmonond RS, Silva AGMDA, Camargo PHC. Controlled synthesis of noble metal nanomaterials: motivation, principles, and opportunities in nanocatalysis. AN ACAD BRAS CIENC 2018; 90:719-744. [PMID: 29668801 DOI: 10.1590/0001-3765201820170561] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 09/06/2017] [Indexed: 11/21/2022] Open
Abstract
This review describes some principles of the controlled synthesis of metal nanoparticles, focusing on how the fundamental understanding of their synthesis in the solution-phase can be put to tailor size, shape, composition, and architecture. The maneuvering over these parameters not only enable the tuning of properties, but also the maximization and optimization of performances for various applications. Herein, we start with a brief description of metallic nanoparticles, highlighting the motivation for achieving physicochemical control in their synthesis. After that, we turn our attention to some important definitions and classifications as well as their unique properties such as surface and quantum effects. Moreover, we discuss the strategies for the controlled synthesis of metal nanomaterials based on the top-down and bottom-up approaches, focusing our discussion on their formation mechanisms in liquid-phase in terms of both thermodynamic and kinetic control. Finally, we point out the promising applications of controlled nanomaterials in the field of nanocatalysis and plasmon-enhanced catalysis, describing some of the current challenges in these fields.
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Affiliation(s)
- Rafael S Geonmonond
- Instituto de Química, Departamento de Química Fundamental, Universidade de São Paulo, Avenida Prof. Lineu Prestes, 748, 05508-000 São Paulo, SP, Brazil
| | - Anderson G M DA Silva
- Instituto de Química, Departamento de Química Fundamental, Universidade de São Paulo, Avenida Prof. Lineu Prestes, 748, 05508-000 São Paulo, SP, Brazil
| | - Pedro H C Camargo
- Instituto de Química, Departamento de Química Fundamental, Universidade de São Paulo, Avenida Prof. Lineu Prestes, 748, 05508-000 São Paulo, SP, Brazil
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Özkar S, Finke RG. Dust Effects on Nucleation Kinetics and Nanoparticle Product Size Distributions: Illustrative Case Study of a Prototype Ir(0) n Transition-Metal Nanoparticle Formation System. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:6550-6562. [PMID: 28640625 DOI: 10.1021/acs.langmuir.7b01219] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The question is addressed if dust is kinetically important in the nucleation and growth of Ir(0)n nanoparticles formed from [Bu4N]5Na3(1,5-COD)IrI·P2W15Nb3O62 (hereafter [(COD)Ir·POM]8-), reduced by H2 in propylene carbonate solvent. Following a concise review of the (often-neglected) literature addressing dust in nucleation phenomena dating back to the late 1800s, the nucleation and growth kinetics of the [(COD)Ir·POM]8- precatalyst system are examined for the effects of 0.2 μm microfiltration of the solvent and precatalyst solution, of rinsing the glassware with that microfiltered solvent, of silanizing the glass reaction vessel, for the addition of <0.2 μm γ-Al2O3 (inorganic) dust, for the addition of flame-made carbon-based (organic) dust, and as a function of the starting, microfiltered [(COD)Ir·POM8-] concentration. Efforts to detect dust and its removal by dynamic light scattering and by optical microscopy are also reported. The results yield a list of eight important conclusions, the four most noteworthy of which are (i) that the nucleation apparent rate "constant" k1obs(bimol) is shown to be slowed by a factor of ∼5 to ∼7.6, depending on the precise experiment and its conditions, just by the filtration of the precatalyst solution using a 0.20 μm filter and rinsing the glassware surface with 0.20 μm filtered propylene carbonate solvent; (ii) that simply employing a 0.20 μm filtration step narrows the size distribution of the resulting Ir(0)n nanoparticles by a factor of 2.4 from ±19 to ±8%, a remarkable result; (iii) that the narrower size distribution can be accounted for by the slowed nucleation rate constant, k1obs(bimol), and by the unchanged autocatalytic growth rate constant, k2obs(bimol), that is, by the increased ratio of k2obs(bimol)/k1obs(bimol) that further separates nucleation from growth in time for filtered vs unfiltered solutions; and (iv) that five lines of evidence indicate that the filterable component of the solution, which has nucleation rate-enhancing and size-dispersion broadening effects, is dust.
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Affiliation(s)
- Saim Özkar
- Department of Chemistry, Middle East Technical University , 06800 Ankara, Turkey
| | - Richard G Finke
- Department of Chemistry, Colorado State University , Fort Collins, Colorado 80523, United States
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Archer AJ, Malijevský A. Crystallization of soft matter under confinement at interfaces and in wedges. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:244017. [PMID: 27116476 DOI: 10.1088/0953-8984/28/24/244017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The surface freezing and surface melting transitions that are exhibited by a model two-dimensional soft matter system are studied. The behaviour when confined within a wedge is also considered. The system consists of particles interacting via a soft purely repulsive pair potential. Density functional theory (DFT) is used to calculate density profiles and thermodynamic quantities. The external potential due to the confining walls is modelled via a hard wall with an additional repulsive Yukawa potential. The surface phase behaviour depends on the range and strength of this repulsion: when the repulsion is weak, the wall promotes freezing at the surface of the wall. The thickness of this frozen layer grows logarithmically as the bulk liquid-solid phase coexistence is approached. Our mean-field DFT predicts that this crystalline layer at the wall must be nucleated (i.e. there is a free energy barrier) and its formation is necessarily a first-order transition, referred to as 'prefreezing', by analogy with the prewetting transition. However, in contrast to the latter, prefreezing cannot terminate in a critical point, since the phase transition involves a change in symmetry. If the wall-fluid interaction is sufficiently long ranged and the repulsion is strong enough, surface melting can occur instead. Then the interface between the wall and the bulk crystalline solid is wetted by the liquid phase as the chemical potential is decreased towards the value at liquid-solid coexistence. It is observed that the finite thickness fluid film at the wall has a broken translational symmetry due to its proximity to the bulk crystal, and so the nucleation of the wetting film can be either first order or continuous. Our mean-field theory predicts that for certain wall potentials there is a premelting critical point analogous to the surface critical point for the prewetting transition. When the fluid is confined within a linear wedge, this can strongly promote freezing when the opening angle of the wedge is commensurate with the crystal lattice.
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Affiliation(s)
- Andrew J Archer
- Department of Mathematical Sciences, Loughborough University, Loughborough LE11 3TU, UK
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Li J, Liu Y, Jiang G, Zhang X. Vapour-to-liquid nucleation in cone pores. MOLECULAR SIMULATION 2015. [DOI: 10.1080/08927022.2014.1001990] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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