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Settem M, Srivastav AK, Kanjarla AK. Understanding the strain-dependent structure of Cu nanocrystals in Ag-Cu nanoalloys. Phys Chem Chem Phys 2021; 23:26165-26177. [PMID: 34797355 DOI: 10.1039/d1cp04145b] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The structure of octahedral Ag-Cu nanoalloys is investigated by means of basin hopping Monte Carlo (BHMC) searches involving the optimization of shape and chemical ordering. Due to the significant size mismatch between Ag and Cu, the misfit strain plays a key role in determining the structure of Ag-Cu nanoalloys. At all the compositions, segregated chemical ordering is observed. However, the shape of the Cu nanocrystal and the associated defects are significantly different. At lower amounts of Cu (as little as 2 atom %), defects close to the surface are observed leading to a highly non-compact shape of the Cu nanocrystal which is non-trivial. The number of Cu-Cu bonds is relatively lower in the non-compact shape which is contrary to the preference of bulk Ag-Cu alloys to maximize the homo-atomic bonds. Due to the non-compact shape, {100} Ag-Cu interfaces are observed which are not expected. As the amount of Cu increases, the Cu nanocrystal undergoes a shape transition from non-compact to a compact octahedron. The associated defect structure is also modified. The structural changes due to the strain effects have been explained by calculating the atomic pressure maps and the bond length distributions. The trends relating to the structure have also been verified at larger sizes.
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Affiliation(s)
- Manoj Settem
- Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai, 600036, India.
| | - Ajeet K Srivastav
- Department of Metallurgical and Materials Engineering, Visvesvaraya National Institute of Technology, Nagpur, 440010, India
| | - Anand K Kanjarla
- Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai, 600036, India. .,Ceramic Technologies Group - Center of Excellence in Materials and Manufacturing for Futuristic Mobility, Indian Institute of Technology Madras, Chennai, 600036, India
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2
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Abstract
PtPd nanoparticles are among the most widely studied nanoscale systems, mainly because of their applications as catalysts in chemical reactions. In this work, a combined experimental-theoretical study is presented about the dependence of growth shape of PtPd alloy nanocrystals on their composition. The particles are grown in the gas phase and characterized by STEM-HRTEM. PtPd nanoalloys present a bimodal size distribution. The size of the larger population can be tuned between 3.8 ± 0.4 and 14.1 ± 2.0 nm by controlling the deposition parameters. A strong dependence of the particle shape on the composition is found: Pd-rich nanocrystals present more rounded shapes whereas Pt-rich ones exhibit sharp tips. Molecular dynamics simulations and excess energy calculations show that the growth structures are out of equilibrium. The growth simulations are able to follow the growth shape evolution and growth pathways at the atomic level, reproducing the structures in good agreement with the experimental results. Finally the optical absorption properties are calculated for PtPd nanoalloys of the same shapes and sizes grown in our experiments.
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3
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Ruffino F. Light-Scattering Simulations from Spherical Bimetallic Core-Shell Nanoparticles. MICROMACHINES 2021; 12:mi12040359. [PMID: 33810270 PMCID: PMC8065638 DOI: 10.3390/mi12040359] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 03/24/2021] [Accepted: 03/24/2021] [Indexed: 12/01/2022]
Abstract
Bimetallic nanoparticles show novel electronic, optical, catalytic or photocatalytic properties different from those of monometallic nanoparticles and arising from the combination of the properties related to the presence of two individual metals but also from the synergy between the two metals. In this regard, bimetallic nanoparticles find applications in several technological areas ranging from energy production and storage to sensing. Often, these applications are based on optical properties of the bimetallic nanoparticles, for example, in plasmonic solar cells or in surface-enhanced Raman spectroscopy-based sensors. Hence, in these applications, the specific interaction between the bimetallic nanoparticles and the electromagnetic radiation plays the dominant role: properties as localized surface plasmon resonances and light-scattering efficiency are determined by the structure and shape of the bimetallic nanoparticles. In particular, for example, concerning core-shell bimetallic nanoparticles, the optical properties are strongly affected by the core/shell sizes ratio. On the basis of these considerations, in the present work, the Mie theory is used to analyze the light-scattering properties of bimetallic core–shell spherical nanoparticles (Au/Ag, AuPd, AuPt, CuAg, PdPt). By changing the core and shell sizes, calculations of the intensity of scattered light from these nanoparticles are reported in polar diagrams, and a comparison between the resulting scattering efficiencies is carried out so as to set a general framework useful to design light-scattering-based devices for desired applications.
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Affiliation(s)
- Francesco Ruffino
- Dipartimento di Fisica e Astronomia "Ettore Majorana", Università di Catania, and CNR-IMM, via S. Sofia 64, 95123 Catania, Italy
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4
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Zhang Z, Ahn J, Kim J, Wu Z, Qin D. Facet-selective deposition of Au and Pt on Ag nanocubes for the fabrication of bifunctional Ag@Au-Pt nanocubes and trimetallic nanoboxes. NANOSCALE 2018; 10:8642-8649. [PMID: 29700542 DOI: 10.1039/c8nr01794h] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We report a facile route to the synthesis of Ag@Au-Pt trimetallic nanocubes in which the Ag, Au, and Pt atoms are exposed at the corners, side faces, and edges, respectively. Our success relies on the use of Ag@Au nanocubes, with Ag2O patches at the corners and Au on the side faces and edges, as seeds for the site-selective deposition of Pt on the edges only in a reaction system containing ascorbic acid (H2Asc) and poly(vinylpyrrolidone). At an initial pH of 3.2, H2Asc can dissolve the Ag2O patches, exposing the Ag atoms at the corners of a nanocube. Upon the injection of the H2PtCl6 precursor, the Pt atoms derived from the reduction by both H2Asc and Ag are preferentially deposited on the edges, leading to the formation of Ag@Au-Pt trimetallic nanocubes. We demonstrate the use of 2,6-dimethylphenyl isocyanide as a molecular probe to confirm and monitor the deposition of Pt atoms on the edges of nanocubes through surface-enhanced Raman scattering (SERS). We further explore the use of these bifunctional trimetallic nanoparticles with integrated plasmonic and catalytic properties for in situ SERS monitoring the reduction of 4-nitrothiophenol by NaBH4. Upon the removal of Ag via H2O2 etching, the Ag@Au-Pt nanocubes evolve into trimetallic nanoboxes with a wall thickness of about 2 nm and well-defined openings at the corners. The trimetallic nanoboxes embrace plasmon resonance peaks in the near-infrared region with potential in biomedical applications.
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Affiliation(s)
- Zhiwei Zhang
- School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.
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5
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Akbarzadeh H, Abbaspour M, Mehrjouei E, Kamrani M. Stability Control of AgPd@Pt Trimetallic Nanoparticles via Ag–Pd Core Structure and Composition: A Molecular Dynamics Study. Ind Eng Chem Res 2018. [DOI: 10.1021/acs.iecr.8b00447] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Hamed Akbarzadeh
- Department of Chemistry, Faculty of Basic Sciences, Hakim Sabzevari University, 96179- 76487 Sabzevar, Iran
| | - Mohsen Abbaspour
- Department of Chemistry, Faculty of Basic Sciences, Hakim Sabzevari University, 96179- 76487 Sabzevar, Iran
| | - Esmat Mehrjouei
- Department of Chemistry, Faculty of Basic Sciences, Hakim Sabzevari University, 96179- 76487 Sabzevar, Iran
| | - Maliheh Kamrani
- Department of Chemistry, Faculty of Basic Sciences, Hakim Sabzevari University, 96179- 76487 Sabzevar, Iran
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Akbarzadeh H, Abbaspour M, Mehrjouei E, Kamrani M. AgPd@Pt nanoparticles with different morphologies of cuboctahedron, icosahedron, decahedron, octahedron, and Marks-decahedron: insights from atomistic simulations. Inorg Chem Front 2018. [DOI: 10.1039/c7qi00748e] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The thermal stabilities of AgPd@Pt nanoclusters with different morphologies have been investigated via MD simulations.
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Affiliation(s)
- Hamed Akbarzadeh
- Department of Chemistry
- Faculty of Basic Sciences
- Hakim Sabzevari University
- 96179-76487 Sabzevar
- Iran
| | - Mohsen Abbaspour
- Department of Chemistry
- Faculty of Basic Sciences
- Hakim Sabzevari University
- 96179-76487 Sabzevar
- Iran
| | - Esmat Mehrjouei
- Department of Chemistry
- Faculty of Basic Sciences
- Hakim Sabzevari University
- 96179-76487 Sabzevar
- Iran
| | - Maliheh Kamrani
- Department of Chemistry
- Faculty of Basic Sciences
- Hakim Sabzevari University
- 96179-76487 Sabzevar
- Iran
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7
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Schafer D, Castegnaro MV, Gorgeski A, Rochet A, Briois V, Alves MCM, Morais J. Controlling the atomic distribution in PtPd nanoparticles: thermal stability and reactivity during NO abatement. Phys Chem Chem Phys 2017; 19:9974-9982. [PMID: 28362013 DOI: 10.1039/c7cp00602k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In situ X-ray absorption spectroscopy and mass spectrometry measurements were employed to simultaneously probe the atom specific short range order and reactivity of Pd and PtPd nanoparticles towards NO decomposition at 300 °C. The nanoparticles were synthesized by a well controlled, eco-friendly wet chemical reduction of metal salts and later supported on activated carbon. Particularly for the bimetallic PtPd samples, distinct atomic arrangements were achieved using a seeding growth method, which allowed producing a random nanoalloy, or nanoparticles with Pt- or Pd-rich core. X-ray photoelectron spectroscopy, transmission electron microscopy, and X-ray diffraction provided additional insights on their electronic, morphological and long range order structural properties. The results revealed that the higher the thermal induced atomic migration observed within the nanoparticles during thermal treatments, the least were their reactivity for NO abatement.
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Affiliation(s)
- D Schafer
- Instituto de Física, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, 91501-970, Brazil.
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8
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Liu R, Zhang LQ, Yu C, Sun MT, Liu JF, Jiang GB. Atomic-Level-Designed Catalytically Active Palladium Atoms on Ultrathin Gold Nanowires. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1604571. [PMID: 27925319 DOI: 10.1002/adma.201604571] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 10/14/2016] [Indexed: 05/26/2023]
Abstract
A Ag monolayer facilitates the deposition of isolated Pd atoms rather than continuous ones on ultrathin Au nanowires. During the hydrogenation of nitrophenol and the electrooxidation of ethanol, these two groups of Pd atoms show distinctive but geometry-dependent catalytic activity. This new atomic geometry maneuvering strategy is ready for the atomically precise design of nanocatalysts.
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Affiliation(s)
- Rui Liu
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China
| | - Li-Qiang Zhang
- State Key Laboratory of Heavy Oil Processing and Department of Materials Science and Engineering, China University of Petroleum, Beijing, 102249, China
| | - Cun Yu
- State Key Laboratory of Heavy Oil Processing and Department of Materials Science and Engineering, China University of Petroleum, Beijing, 102249, China
| | - Meng-Tao Sun
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Jing-Fu Liu
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China
| | - Gui-Bin Jiang
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China
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9
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De Clercq A, Giorgio S, Mottet C. Pd surface and Pt subsurface segregation in Pt1-c Pd c nanoalloys. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:064006. [PMID: 26795206 DOI: 10.1088/0953-8984/28/6/064006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The structure and chemical arrangement of Pt1-c Pd c nanoalloys with the icosahedral and face centered cubic symmetry are studied using Monte Carlo simulations with a tight binding interatomic potential fitted to density-functional theory calculations. Pd surface segregation from the lowest to the highest coordinated sites is predicted by the theory together with a Pt enrichment at the subsurface, whatever the structure and the size of the nanoparticles, and which subsists when increasing the temperature. The onion-shell chemical configuration is found for both symmetries and is initiated from the Pd surface segregation. It is amplified in the icosahedral symmetry and small sizes but when considering larger sizes, the oscillating segregation profile occurs near the surface on about three to four shells whatever the structure. Pd segregation results from the significant lower cohesive energy of Pd as compared to Pt and the weak ordering tendency leads to the Pt subsurface segregation. The very weak size mismatch does not prevent the bigger atoms (Pt) from occupying subsurface sites which are in compression whereas the smaller ones (Pd) occupy the central site of the icosahedra where the compression is an order of magnitude higher.
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Affiliation(s)
- A De Clercq
- Aix Marseille Université, CNRS, CINaM UMR7325, Campus de Luminy, F-13288 Marseille, France. Aix Marseille Université, CNRS, MADIREL UMR7246, 13397 Marseille, France
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10
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Pei Y, Maligal-Ganesh RV, Xiao C, Goh TW, Brashler K, Gustafson JA, Huang W. An inorganic capping strategy for the seeded growth of versatile bimetallic nanostructures. NANOSCALE 2015; 7:16721-16728. [PMID: 26399612 DOI: 10.1039/c5nr04614a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Metal nanostructures have attracted great attention in various fields due to their tunable properties through precisely tailored sizes, compositions and structures. Using mesoporous silica (mSiO2) as the inorganic capping agent and encapsulated Pt nanoparticles as the seeds, we developed a robust seeded growth method to prepare uniform bimetallic nanoparticles encapsulated in mesoporous silica shells (PtM@mSiO2, M = Pd, Rh, Ni and Cu). Unexpectedly, we found that the inorganic silica shell is able to accommodate an eight-fold volume increase in the metallic core by reducing its thickness. The bimetallic nanoparticles encapsulated in mesoporous silica shells showed enhanced catalytic properties and thermal stabilities compared with those prepared with organic capping agents. This inorganic capping strategy could find a broad application in the synthesis of versatile bimetallic nanostructures with exceptional structural control and enhanced catalytic properties.
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Affiliation(s)
- Yuchen Pei
- Department of Chemistry, Iowa State University, Ames Laboratory, U.S. Department of Energy, Ames, 50011, USA.
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11
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Zhou W, Li X, Zhu GZ. Statistical Study of Beam-Induced Motion of Gold Adatoms by a Scanning TEM. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2015; 21:617-625. [PMID: 25951837 DOI: 10.1017/s1431927615000574] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In order to achieve reliable structural characterization by transmission electron microscopy, beam-induced structural changes should be clarified for any target material system. As an example, the movement of heavy adatoms on a thin carbon support has been repeatedly reported under the electron beam while the underlying reason for such motion is still in debate. By applying statistical analysis to the group behavior of gold adatoms, we investigated their motion under different beam conditions and detected features corresponding to beam-induced motion, under typical scanning transmission electron microscopy observation conditions. Our results are consistent with the theoretical prediction proposed by Egerton (2013).
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Affiliation(s)
- Wei Zhou
- State Key Laboratory of Metal Matrix Composites,School of Materials Science and Engineering,Shanghai Jiao Tong University,800 Dongchuan Road,Shanghai 200240,P. R. China
| | - Xin Li
- State Key Laboratory of Metal Matrix Composites,School of Materials Science and Engineering,Shanghai Jiao Tong University,800 Dongchuan Road,Shanghai 200240,P. R. China
| | - Guo-zhen Zhu
- State Key Laboratory of Metal Matrix Composites,School of Materials Science and Engineering,Shanghai Jiao Tong University,800 Dongchuan Road,Shanghai 200240,P. R. China
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12
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Pannu C, Bala M, Khan SA, Srivastava SK, Kabiraj D, Avasthi DK. Synthesis and characterization of Au–Fe alloy nanoparticles embedded in a silica matrix by atom beam sputtering. RSC Adv 2015. [DOI: 10.1039/c5ra19136j] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
AuFe alloy nanoparticles (NPs) embedded in a silica matrix were synthesized using an atom beam sputtering setup. Increasing the metal fraction in the thin films from 16 at% to 33 at% results in the formation of alloy NPs.
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Affiliation(s)
| | - Manju Bala
- Inter University Accelerator Centre
- New Delhi
- India
| | - S. A. Khan
- Inter University Accelerator Centre
- New Delhi
- India
| | - S. K. Srivastava
- Department of Physics
- Indian Institute of Technology Kharagpur
- India
| | - D. Kabiraj
- Inter University Accelerator Centre
- New Delhi
- India
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13
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Khanal S, Spitale A, Bhattarai N, Bahena D, Velazquez-Salazar JJ, Mejía-Rosales S, M. Mariscal M, José-Yacaman M. Synthesis, characterization, and growth simulations of Cu-Pt bimetallic nanoclusters. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2014; 5:1371-1379. [PMID: 25247120 PMCID: PMC4168864 DOI: 10.3762/bjnano.5.150] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 08/06/2014] [Indexed: 06/03/2023]
Abstract
Highly monodispersed Cu-Pt bimetallic nanoclusters were synthesized by a facile synthesis approach. Analysis of transmission electron microscopy (TEM) and spherical aberration (C s)-corrected scanning transmission electron microscopy (STEM) images shows that the average diameter of the Cu-Pt nanoclusters is 3.0 ± 1.0 nm. The high angle annular dark field (HAADF-STEM) images, intensity profiles, and energy dispersive X-ray spectroscopy (EDX) line scans, allowed us to study the distribution of Cu and Pt with atomistic resolution, finding that Pt is embedded randomly in the Cu lattice. A novel simulation method is applied to study the growth mechanism, which shows the formation of alloy structures in good agreement with the experimental evidence. The findings give insight into the formation mechanism of the nanosized Cu-Pt bimetallic catalysts.
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Affiliation(s)
- Subarna Khanal
- Department of Physics and Astronomy, University of Texas at San Antonio, One UTSA Circle, 78249, San Antonio, Texas, USA
| | - Ana Spitale
- INFIQC, CONICET, Departamento de Matemática y Física, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, (XUA5000) Córdoba, Argentina
| | - Nabraj Bhattarai
- Department of Physics and Astronomy, University of Texas at San Antonio, One UTSA Circle, 78249, San Antonio, Texas, USA
| | - Daniel Bahena
- Department of Physics and Astronomy, University of Texas at San Antonio, One UTSA Circle, 78249, San Antonio, Texas, USA
| | - J Jesus Velazquez-Salazar
- Department of Physics and Astronomy, University of Texas at San Antonio, One UTSA Circle, 78249, San Antonio, Texas, USA
| | - Sergio Mejía-Rosales
- Center for Innovation and Research in Engineering and Technology, and CICFIM-Facultad de Ciencias Físico-Matemáticas, Universidad Autónoma de Nuevo León, San Nicolás de los Garza, NL 66450, México
| | - Marcelo M. Mariscal
- INFIQC, CONICET, Departamento de Matemática y Física, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, (XUA5000) Córdoba, Argentina
| | - Miguel José-Yacaman
- Department of Physics and Astronomy, University of Texas at San Antonio, One UTSA Circle, 78249, San Antonio, Texas, USA
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14
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Khanal S, Bhattarai N, McMaster D, Bahena D, Velazquez-Salazar JJ, Jose-Yacaman M. Highly monodisperse multiple twinned AuCu-Pt trimetallic nanoparticles with high index surfaces. Phys Chem Chem Phys 2014; 16:16278-83. [PMID: 24975090 PMCID: PMC4128576 DOI: 10.1039/c4cp02208d] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Trimetallic nanoparticles possess different properties than their mono- and bi-metallic counterparts, opening a wide range of possibilities for diverse potential applications with the notion to study possible morphology, atomic ordering, reduce precious metal consumption and many others. In this paper, we present a comprehensive experimental study on AuCu-Pt trimetallic nanoparticles with an average diameter of 15 ± 1.0 nm, synthesized in a one-pot synthesis method and characterized by the Cs-corrected scanning transmission electron microscopy technique that allowed us to probe the structure at the atomic level resolution. A new way to control the nanoparticle morphology by the presence of third metal (Pt) is also discussed by the overgrowth of Pt on the as prepared AuCu core by Frank-van der Merwe (FM) layer-by-layer and Stranski-Krastanov (SK) island-on-wetting-layer growth modes. With the application of this research, we are now a step closer to produce optimum catalysts in which the active phase forms only surface monolayers. In addition, the nanoalloy exhibits high index facet surfaces with {211} and {321} families that are highly open-structure surfaces and are interesting for the catalytic applications.
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Affiliation(s)
- Subarna Khanal
- Department of Physics and Astronomy, University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249, USA.
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15
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Khanal S, Bhattarai N, Velázquez-Salazar JJ, Bahena D, Soldano G, Ponce A, Mariscal MM, Mejía-Rosales S, José-Yacamán M. Trimetallic nanostructures: the case of AgPd-Pt multiply twinned nanoparticles. NANOSCALE 2013; 5:12456-63. [PMID: 24165796 PMCID: PMC3918169 DOI: 10.1039/c3nr03831a] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We report the synthesis, structural characterization, and atomistic simulations of AgPd-Pt trimetallic (TM) nanoparticles. Two types of structure were synthesized using a relatively facile chemical method: multiply twinned core-shell, and hollow particles. The nanoparticles were small in size, with an average diameter of 11 nm and a narrow distribution, and their characterization by aberration corrected scanning transmission electron microscopy allowed us to probe the structure of the particles at an atomistic level. In some nanoparticles, the formation of a hollow structure was also observed, that facilitates the alloying of Ag and Pt in the shell region and the segregation of Ag atoms on the surface, affecting the catalytic activity and stability. We also investigated the growth mechanism of the nanoparticles using grand canonical Monte Carlo simulations, and we have found that Pt regions grow at overpotentials on the AgPd nanoalloys, forming 3D islands at the early stages of the deposition process. We found very good agreement between the simulated structures and those observed experimentally.
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Affiliation(s)
- Subarna Khanal
- Department of Physics and Astronomy, University of Texas at San Antonio, One UTSA Circle, San Antonio, Texas 78249, USA.
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16
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Khanal S, Casillas G, Bhattarai N, Velázquez-Salazar JJ, Santiago U, Ponce A, Mejía-Rosales S, José-Yacamán M. CuS2-passivated Au-core, Au3Cu-shell nanoparticles analyzed by atomistic-resolution Cs-corrected STEM. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:9231-9. [PMID: 23802756 PMCID: PMC3805048 DOI: 10.1021/la401598e] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Au-core, Au3Cu-alloyed shell nanoparticles passivated with CuS2 were fabricated by the polyol method, and characterized by Cs-corrected scanning transmission electron microscopy. The analysis of the high-resolution micrographs reveals that these nanoparticles have decahedral structure with shell periodicity, and that each of the particles is composed by Au core and Au3Cu alloyed shell surrounded by CuS2 surface layer. X-ray diffraction measurements and results from numerical simulations confirm these findings. From the atomic resolution micrographs, we identified edge dislocations at the twin boundaries of the particles, as well as evidence of the diffusion of Cu atoms into the Au region, and the reordering of the lattice on the surface, close to the vertices of the particle. These defects will impact the atomic and electronic structures, thereby changing the physical and chemical properties of the nanoparticles. On the other hand, we show for the first time the formation of an ordered superlattice of Au3Cu and a self-capping layer made using one of the alloy metals. This has significant consequences on the physical mechanism that form multicomponent nanoparticles.
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Affiliation(s)
- Subarna Khanal
- Department of Physics and Astronomy, University of Texas at San Antonio, One UTSA Circle, San Antonio, Texas 78249, USA
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Bhattarai N, Khanal S, Pudasaini PR, Pahl S, Romero-Urbina D. Citrate Stabilized Silver Nanoparticles. ACTA ACUST UNITED AC 2011. [DOI: 10.4018/ijnmc.2011070102] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Citrate stabilized silver (Ag) colloidal solution were synthesized and characterized for crystallographic and surface properties by using transmission electron microscopy (TEM) and zeta potential measurement techniques. TEM investigation depicted the size of Ago ranges from 5 to 50 nm with smaller particles having single crystal structure while larger particles with structural defects (such as multiply twinned, high coalescence and Moire patterns). ?-potential measurement confirms the presence of Ag+ in nAg stock solution. The shift in ?-potential measurement by +25.1 mV in the filtered solution suggests the presence of Ag+ in Ago nanoparticles.
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Affiliation(s)
- Nabraj Bhattarai
- Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX, USA
| | - Subarna Khanal
- Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX, USA
| | - Pushpa Raj Pudasaini
- Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX, USA
| | - Shanna Pahl
- Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX, USA
| | - Dulce Romero-Urbina
- Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX, USA
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