1
|
Kataoka-Hamai C, Kawakami K. Ostwald Ripening of Triacylglycerol Droplets Embedded in Glass-Supported Phospholipid Bilayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:10001-10010. [PMID: 37433207 DOI: 10.1021/acs.langmuir.3c00835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/13/2023]
Abstract
Lipid droplets are fat storage organelles that consist of a neutral lipid core surrounded by a phospholipid monolayer. Because of their important biological functions, reconstituting model lipid droplets in synthetic phospholipid membranes is of great interest. In the present study, we investigated the incorporation of triacylglycerol droplets into glass-supported phospholipid bilayers by using fluorescence microscopy. We adsorbed triolein emulsions onto a glass surface that was partially covered with planar bilayers. After adsorption, triolein droplets were found to be immobilized in the bilayer membrane. The volume of each bound droplet varied over time. Large droplets grew, whereas small droplets shrank. Additionally, data on fluorescence recovery after photobleaching obtained for a phospholipid probe indicate that phospholipids on and near triolein droplets were fully mobile. Furthermore, photobleaching data obtained for a triacylglycerol probe indicate that triolein molecules diffused between different droplets along the planar bilayer. These results demonstrate Ostwald ripening, where triolein molecules in a small droplet dissolved in the bilayer, diffused laterally, and eventually bound to the interfaces of larger droplets. We investigated the ripening rate by using the average of the cube root of the fluorescence emission obtained for individual droplets. The ripening slowed after the addition of trilinolein to the triolein phase. Finally, we investigated the time dependence of the size distributions of the triolein droplets. The distribution was initially nearly unimodal and subsequently became bimodal.
Collapse
Affiliation(s)
- Chiho Kataoka-Hamai
- Research Center for Macromolecules and Biomaterials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Kohsaku Kawakami
- Research Center for Macromolecules and Biomaterials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
- Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577, Japan
| |
Collapse
|
2
|
Zhdanov VP. Comment on "Real-time atomistic simulation of the Ostwald ripening of TiO 2 supported Au nanoparticles" by B. Zhu, R. Qi, L. Yuan and Y. Gao, Nanoscale, 2020, 12, 19142. NANOSCALE 2022; 14:16321-16323. [PMID: 36285473 DOI: 10.1039/d1nr05352c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Using Monte Carlo simulations (MCS) in combination with an analytical model for the metal-metal interaction with the parameters based on density functional theory (DFT), Zhu, Qi, Yuan, and Gao predicted that the Ostwald ripening of Au nanoparticles on TiO2 occurs primarily via the detachment and attachment of Au dimers. I show that this and some other predictions are not properly validated because the parameters employed in the analytical model in order to describe the Au-Au interaction are in fact inconsistent both with DFT and experimental thermodynamical data.
Collapse
Affiliation(s)
- Vladimir P Zhdanov
- Department of Physics, Chalmers University of Technology, Göteborg, Sweden.
- Boreskov Institute of Catalysis, Russian Academy of Sciences, Novosibirsk, Russia
| |
Collapse
|
3
|
Preparation of Pt/Al2O3 and PtPd/Al2O3 catalysts by supercritical deposition and their performance for oxidation of nitric oxide and propene. Catal Today 2022. [DOI: 10.1016/j.cattod.2020.11.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
4
|
Horwath JP, Voorhees PW, Stach EA. Quantifying Competitive Degradation Processes in Supported Nanocatalyst Systems. NANO LETTERS 2021; 21:5324-5329. [PMID: 34109786 DOI: 10.1021/acs.nanolett.1c01516] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The stability of supported metal nanoparticles determines the activity and lifetime of heterogeneous catalysts. Catalysts can destabilize through several thermodynamic and kinetic pathways, and the competition between these mechanisms complicates efforts to quantify and predict the overall evolution of supported nanoparticles in reactive environments. Pairing in situ transmission electron microscopy with unsupervised machine learning, we quantify the destabilization of hundreds of supported Au nanoparticles in real-time to develop a model describing the observed particle evolution as a competition between evaporation and surface diffusion. Data mining of particle evolution statistics allows us to determine physically reasonable values for the model parameters, quantify the particle size at which the Gibbs-Thomson pressure accelerates the evaporation process, and explore how individual particle interactions deviate from the mean-field model. This approach can be applied to a wide range of supported nanoparticle systems, allowing quantitative insight into the mechanisms that control their evolution in reactive environments.
Collapse
Affiliation(s)
- James P Horwath
- University of Pennsylvania, Department of Materials Science and Engineering, Philadelphia, Pennsylvania 19104, United States
| | - Peter W Voorhees
- Northwestern University, Department of Materials Science and Engineering, Evanston, Illinois 60208, United States
| | - Eric A Stach
- University of Pennsylvania, Department of Materials Science and Engineering, Philadelphia, Pennsylvania 19104, United States
| |
Collapse
|
5
|
Prinz N, Schwensow L, Wendholt S, Jentys A, Bauer M, Kleist W, Zobel M. Hard X-ray-based techniques for structural investigations of CO 2 methanation catalysts prepared by MOF decomposition. NANOSCALE 2020; 12:15800-15813. [PMID: 32691790 DOI: 10.1039/d0nr01750g] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Thermal decomposition of metal-organic framework (MOF) precursors is a recent method to create well-dispersed metal centers within active catalyst materials with enhanced stability, as required for dynamic operation conditions in light of challenges caused by the renewable energy supply. Here, we use a hard X-ray-based toolbox of pair distribution function (PDF) and X-ray absorption spectroscopy (XAS) analysis combined with X-ray diffraction and catalytic activity tests to investigate structure-activity correlations of methanation catalysts obtained by thermal decomposition of a Ni(BDC)(PNO) MOF precursor. Increasing the decomposition temperature from 350 to 500 °C resulted in Nifcc nanoparticles with increasing particle sizes, alongside a decrease in Ni2+ species and strain-induced peak broadening. For lower temperatures and inert atmosphere, Ni3C and NiO phases co-existed. A graphitic shell stabilized the Ni particles. Compared to an inert atmosphere, reducing conditions led to larger particles and a faster decomposition of the MOF precursor. Catalytic studies revealed that the decomposition at an intermediate temperature of 375 °C in 5% H2/He is the best set of parameters to obtain high specific surface areas while maintaining particle sizes that feature many active Ni centers for the formation of CH4.
Collapse
Affiliation(s)
- Nils Prinz
- Chemistry Department, University Bayreuth, Universitätsstr. 30, Bayreuth 95447, Germany.
| | | | | | | | | | | | | |
Collapse
|
6
|
Rahmati M, Safdari MS, Fletcher TH, Argyle MD, Bartholomew CH. Chemical and Thermal Sintering of Supported Metals with Emphasis on Cobalt Catalysts During Fischer–Tropsch Synthesis. Chem Rev 2020; 120:4455-4533. [DOI: 10.1021/acs.chemrev.9b00417] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Mahmood Rahmati
- Department of Chemical Engineering, Brigham Young University, Provo, Utah 84602, United States
| | - Mohammad-Saeed Safdari
- Department of Chemical Engineering, Brigham Young University, Provo, Utah 84602, United States
| | | | - Morris D. Argyle
- Department of Chemical Engineering, Brigham Young University, Provo, Utah 84602, United States
| | - Calvin H. Bartholomew
- Department of Chemical Engineering, Brigham Young University, Provo, Utah 84602, United States
| |
Collapse
|
7
|
Gommes CJ. Ostwald ripening of confined nanoparticles: chemomechanical coupling in nanopores. NANOSCALE 2019; 11:7386-7393. [PMID: 30938749 DOI: 10.1039/c9nr01349k] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Ostwald ripening is a major source of deactivation of functional nanomaterials. It consists in the growth of large nanoparticles at the expense of smaller ones via the formation and decomposition of intermediate chemical species. In most materials of practical interest nanoparticles are dispersed in porous supports with which they interact mechanically. We analyze the consequences of this chemo-mechanical coupling on both kinetic and equilibrium aspects of Ostwald ripening. We show that the long-term stability of a collection of confined nanoparticles depends on nucleation-like events, whereby few particles break through the pore walls early in the process and later grow at the expense of all other particles. This notably explains why the stability of confined nanoparticles depends critically on their initial size distribution; it also provides an explanation for the occasional observation of bimodal particle size distributions in aged materials.
Collapse
Affiliation(s)
- Cedric J Gommes
- Department of Chemical Engineering, University of Liège, B6 A, 3 allée du 6 août, B-4000 Liège, Belgium.
| |
Collapse
|
8
|
Prévot G, Nguyen NT, Alloyeau D, Ricolleau C, Nelayah J. Ostwald-Driven Phase Separation in Bimetallic Nanoparticle Assemblies. ACS NANO 2016; 10:4127-4133. [PMID: 26989906 DOI: 10.1021/acsnano.5b07377] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The compositional stability of bimetallic nanoparticles (NPs) is crucial for many applications. We have studied the coarsening of amorphous carbon-supported Au-Pd NPs during annealing at 873 K. Using scanning transmission electron microscopy and energy-dispersive spectroscopy measurements, we show that, despite a complete miscibility of the two metals, the particle assembly undergoes a phase separation during annealing, which leads to two distinct populations: Au-rich NPs with a mean radius of 3.5 nm and large Pd-rich NPs with a mean radius of 25 nm. Thermodynamic calculations and kinetic Monte Carlo simulations explain this behavior that is driven by the competition between surface and mixing energy and by the different mobilities of the two atomic species.
Collapse
Affiliation(s)
- Geoffroy Prévot
- Sorbonne Universités, UPMC Univ Paris 06, CNRS-UMR 7588, Institut des NanoSciences de Paris , 75005 Paris, France
| | - Nhat Tai Nguyen
- Laboratoire de Matériaux et Phénomènes Quantiques, Bâtiment Condorcet, CNRS UMR 7162, Université Paris Diderot , 75013 Paris, France
| | - Damien Alloyeau
- Laboratoire de Matériaux et Phénomènes Quantiques, Bâtiment Condorcet, CNRS UMR 7162, Université Paris Diderot , 75013 Paris, France
| | - Christian Ricolleau
- Laboratoire de Matériaux et Phénomènes Quantiques, Bâtiment Condorcet, CNRS UMR 7162, Université Paris Diderot , 75013 Paris, France
| | - Jaysen Nelayah
- Laboratoire de Matériaux et Phénomènes Quantiques, Bâtiment Condorcet, CNRS UMR 7162, Université Paris Diderot , 75013 Paris, France
| |
Collapse
|
9
|
Martin TE, Gai PL, Boyes ED. Dynamic Imaging of Ostwald Ripening by Environmental Scanning Transmission Electron Microscopy. ChemCatChem 2015. [DOI: 10.1002/cctc.201500830] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Thomas E. Martin
- The York Nanocentre and Department of Physics; University of York; Heslington York YO10 5DD UK
| | - Pratibha L. Gai
- The York Nanocentre and Department of Physics; University of York; Heslington York YO10 5DD UK
- Department of Chemistry; University of York; Heslington York YO10 5DD UK
| | - Edward D. Boyes
- The York Nanocentre and Department of Physics; University of York; Heslington York YO10 5DD UK
- Department of Electronics; University of York; Heslington York YO10 5DD UK
| |
Collapse
|
10
|
|
11
|
Lai C, Kolla P, Zhao Y, Fong H, Smirnova AL. Lignin-derived electrospun carbon nanofiber mats with supercritically deposited Ag nanoparticles for oxygen reduction reaction in alkaline fuel cells. Electrochim Acta 2014. [DOI: 10.1016/j.electacta.2014.03.006] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
12
|
Fattori N, Maroneze CM, da Costa LP, Strauss M, Sigoli FA, Mazali IO, Gushikem Y. Ion-exchange properties of imidazolium-grafted SBA-15 toward AuCl4(-) anions and their conversion into supported gold nanoparticles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:10281-10288. [PMID: 22697479 DOI: 10.1021/la301374z] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Imidazolium groups were successfully prepared and grafted on the surface of SBA-15 mesoporous silica. The ion-exchange properties of the functionalized porous solid (SBA-15/R(+)Cl(-)) toward AuCl(4)(-) anions were evaluated through an ion-exchange isotherm. The calculated values of the equilibrium constant (log β = 4.47) and the effective ion-exchange capacity (t(Q) = 0.79 mmol g(-1)) indicate that the AuCl(4)(-) species can be loaded and strongly retained on the functionalized surface as counterions of the imidazolium groups. Subsequently, solids containing different amounts of AuCl(4)(-) ions were submitted to a chemical reduction process with NaBH(4), converting the anionic gold species into supported gold nanoparticles. The plasmon resonance bands, the X-ray diffraction patterns, and transmission electron microscopy images of the supported gold nanoparticles before and after thermal treatment at 973 K indicate that the metal nanostructures are highly dispersed and stabilized by the host environment.
Collapse
Affiliation(s)
- Natalia Fattori
- Institute of Chemistry, University of Campinas (UNICAMP), Campinas, São Paulo (SP), Brazil
| | | | | | | | | | | | | |
Collapse
|