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Abstract
Highly fluorescent, water-soluble, few-atom noble-metal quantum dots have been created that behave as multielectron artificial atoms with discrete, size-tunable electronic transitions throughout the visible and near infrared. These molecular metals exhibit highly polarizable transitions and scale in size according to the simple relation E(Fermi)/N(1/3), predicted by the free-electron model of metallic behavior. This simple scaling indicates that fluorescence arises from intraband transitions of free electrons, and these conduction-electron transitions are the low-number limit of the plasmon-the collective dipole oscillations occurring when a continuous density of states is reached. Providing the missing link between atomic and nanoparticle behavior in noble metals, these emissive, water-soluble Au nanoclusters open new opportunities for biological labels, energy-transfer pairs, and light-emitting sources in nanoscale optoelectronics.
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Affiliation(s)
- Jie Zheng
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400,
| | - Philip R. Nicovich
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400,
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202
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Varanda LC, Jafelicci M. Self-assembled FePt nanocrystals with large coercivity: reduction of the fcc-to-L1(0) ordering temperature. J Am Chem Soc 2007; 128:11062-6. [PMID: 16925422 DOI: 10.1021/ja060711i] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Herein we report the synthesis and properties of Fe(55)Pt(45) nanoparticles, both monodisperse and self-assembled into hexagonal close-packed and cubic arrays of 4.0 +/- 0.2 nm size in an L1(0) structure, obtained by a modified polyol process. The new synthetic route improved the control over the particle composition, thereby reducing the temperature required to convert from face-centered cubic (fcc) to face-centered tetragonal (fct) phase by some 30-50 degrees C without additives. Annealing at 550 degrees C for 30 min converts the self-assembled nanoparticles into ferromagnetic nanocrystals with large coercivity, H(C) = 11.1 kOe. Reducing the fcc-to-fct (L1(0)) ordering temperature avoided particle coalescence and decreased the loss in particle positional order without compromising the magnetic properties, as is generally observed when additives are used.
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Affiliation(s)
- Laudemir Carlos Varanda
- Laboratory of Magnetic Materials and Colloids, Department of Physical Chemistry, Institute of Chemistry, Universidade Estadual Paulista (UNESP), P.O. Box 355, 14801-970 Araraquara, São Paulo, Brazil
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203
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Au/Titania Composite Nanoparticle Arrays with Controlled Size and Spacing by Organic-Inorganic Nanohybridization in Thin Film Block Copolymer Templates. B KOREAN CHEM SOC 2007. [DOI: 10.5012/bkcs.2007.28.6.1015] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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204
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Park J, Bauer S, von der Mark K, Schmuki P. Nanosize and vitality: TiO2 nanotube diameter directs cell fate. NANO LETTERS 2007; 7:1686-91. [PMID: 17503870 DOI: 10.1021/nl070678d] [Citation(s) in RCA: 719] [Impact Index Per Article: 42.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
We generated, on titanium surfaces, self-assembled layers of vertically oriented TiO2 nanotubes with defined diameters between 15 and 100 nm and show that adhesion, spreading, growth, and differentiation of mesenchymal stem cells are critically dependent on the tube diameter. A spacing less than 30 nm with a maximum at 15 nm provided an effective length scale for accelerated integrin clustering/focal contact formation and strongly enhances cellular activities compared to smooth TiO2 surfaces. Cell adhesion and spreading were severely impaired on nanotube layers with a tube diameter larger than 50 nm, resulting in dramatically reduced cellular activity and a high extent of programmed cell death. Thus, on a TiO2 nanotube surface, a lateral spacing geometry with openings of 30-50 nm represents a critical borderline for cell fate.
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Affiliation(s)
- Jung Park
- Department of Experimental Medicine I, Nikolaus Fiebiger-Center of Molecular Medicine, Germany
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205
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Low-temperature water-gas shift reaction on Au/CeO2 catalysts – the influence of catalyst pre-treatment on the activity and deactivation in idealized reformate. Catal Letters 2007. [DOI: 10.1007/s10562-007-9111-z] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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206
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Shichibu Y, Negishi Y, Tsunoyama H, Kanehara M, Teranishi T, Tsukuda T. Extremely high stability of glutathionate-protected Au25 clusters against core etching. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2007; 3:835-9. [PMID: 17352431 DOI: 10.1002/smll.200600611] [Citation(s) in RCA: 159] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Affiliation(s)
- Yukatsu Shichibu
- Research Center for Molecular-Scale Nanoscience, Institute for Molecular Science, Myodaiji, Okazaki, Japan
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207
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208
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Lim DC, Dietsche R, Bubek M, Ketterer T, Ganteför G, Kim YD. Chemistry of mass-selected Au clusters deposited on sputter-damaged HOPG surfaces: The unique properties of Au8 clusters. Chem Phys Lett 2007. [DOI: 10.1016/j.cplett.2007.04.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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209
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Zhao L, Siu ACL, Petrus JA, He Z, Leung KT. Interfacial Bonding of Gold Nanoparticles on a H-terminated Si(100) Substrate Obtained by Electro- and Electroless Deposition. J Am Chem Soc 2007; 129:5730-4. [PMID: 17411051 DOI: 10.1021/ja070441j] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Dome-shaped gold nanoparticles (with an average diameter of 10.5 nm) are grown on H-terminated Si(100) substrates by simple techniques involving electro- and electroless deposition from a 0.05 mM AuCl3 and 0.1 M NaClO4 solution. XPS depth profiling data (involving Au 4f core-level and valence band spectra) reveal for the first time the formation of gold silicide at the interface between the Au nanoparticles and Si substrate. UV-visible diffuse reflectance spectra indicate that both samples have surface plasmon resonance maxima at 558 nm, characteristic of an uniform distribution of Au nanoscale particles of sufficiently small size. Glancing-incidence XRD patterns clearly show that the deposited Au nanoparticles belong to the fcc phase, with the relative intensity of the (220) plane for Au nanoparticles obtained by electroless deposition found to be notably larger than that by electrodeposition.
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Affiliation(s)
- Liyan Zhao
- WATLab, and Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
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210
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Antibacterial efficacy of aminoglycosidic antibiotics protected gold nanoparticles—A brief study. Colloids Surf A Physicochem Eng Asp 2007. [DOI: 10.1016/j.colsurfa.2006.10.024] [Citation(s) in RCA: 200] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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211
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Abstract
Catalysis by gold has rapidly become a hot topic in chemistry, with a new discovery being made almost every week. Gold is equally effective as a heterogeneous or a homogeneous catalyst and in this Review we attempt to marry these two facets to demonstrate this new found and general efficacy of gold. The latest discoveries are placed within a historical context, but the main thrust is to highlight the new catalytic possibilities that gold-catalyzed reactions currently offer the synthetic chemist, in particular in redox reactions and nucleophilic additions to pi systems. Indeed gold has proved to be an effective catalyst for many reactions for which a catalyst had not been previously identified, and many new discoveries are still expected.
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Affiliation(s)
- A Stephen K Hashmi
- Institut für Organische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
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212
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Zhi Fu Y, Kou Du Y, Yang P, Ru Li J, Jiang L. Size‐Controlled Synthesis of Highly Monodisperse Gold Nanoparticles without a Size‐Selection and Long Range Ordered 2‐D Arrangement. J DISPER SCI TECHNOL 2007. [DOI: 10.1080/01932690601062150] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Yun Zhi Fu
- a Department of Chemistry , Suzhou University , Suzhou , P. R. China
- b Key Laboratory of Colloids and Surfaces , Institute of Chemistry, Chinese Academy of Sciences , Beijing , P. R. China
| | - Yu Kou Du
- a Department of Chemistry , Suzhou University , Suzhou , P. R. China
| | - Ping Yang
- a Department of Chemistry , Suzhou University , Suzhou , P. R. China
| | - Jin Ru Li
- b Key Laboratory of Colloids and Surfaces , Institute of Chemistry, Chinese Academy of Sciences , Beijing , P. R. China
| | - Long Jiang
- b Key Laboratory of Colloids and Surfaces , Institute of Chemistry, Chinese Academy of Sciences , Beijing , P. R. China
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213
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Effect of interparticle interaction on the low temperature oxidation of CO over size-selected Au nanocatalysts supported on ultrathin TiC films. Catal Letters 2007. [DOI: 10.1007/s10562-007-9027-7] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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214
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Coker EN, Steen WA, Miller JT, Kropf AJ, Miller JE. The preparation and characterization of novel Pt/C electrocatalysts with controlled porosity and cluster size. ACTA ACUST UNITED AC 2007. [DOI: 10.1039/b703916f] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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215
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216
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Xu C, Su J, Xu X, Liu P, Zhao H, Tian F, Ding Y. Low Temperature CO Oxidation over Unsupported Nanoporous Gold. J Am Chem Soc 2006; 129:42-3. [PMID: 17199279 DOI: 10.1021/ja0675503] [Citation(s) in RCA: 311] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Supported Au nanoclusters are well-known for their unusual properties in catalysis. We describe here that nanostructured porous Au made via dealloying represents a new class of unsupported catalysts with extraordinary activities in important reactions such as CO oxidation. Although nanoporous Au may contain some oxides on the surface, our results demonstrate that it is metallic Au that plays the main role in this catalytic reaction. Furthermore, this material has good low-temperature catalytic stability and is extremely CO tolerant.
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Affiliation(s)
- Caixia Xu
- Key Laboratory of Colloid and Interface Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China
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217
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218
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Alexeev OS, Siani A, Lafaye G, Williams CT, Ploehn HJ, Amiridis MD. EXAFS Characterization of Dendrimer−Pt Nanocomposites Used for the Preparation of Pt/γ-Al2O3Catalysts. J Phys Chem B 2006; 110:24903-14. [PMID: 17149911 DOI: 10.1021/jp063787+] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Pt/gamma-Al2O3 catalysts were prepared using hydroxyl-terminated generation four (G4OH) PAMAM dendrimers as the templating agents and the various steps of the preparation process were monitored by extended X-ray absorption fine structure (EXAFS) spectroscopy. The EXAFS results indicate that, upon hydrolysis, chlorine ligands in the H(2)PtCl(6) and K(2)PtCl(4) precursors were partially replaced by aquo ligands to form [PtCl3(H2O)3]+ and [PtCl2(H2O)2] species, respectively. The results further suggest that, after interaction of such species with the dendrimer molecules, chlorine ligands from the first coordination shell of Pt were replaced by nitrogen atoms from the dendrimer interior, indicating that complexation took place. This process was accompanied by a substantial transfer of electron density from the dendrimer to platinum, indicating that the dendrimer plays the role of a ligand. Following treatment of the H(2)PtCl(6)/G4OH and K(2)PtCl(4)/G4OH complexes with NaBH4, no substantial changes were observed in the electronic or coordination environment of platinum, indicating that metal nanoparticles were not formed during this step under our experimental conditions. However, when the reduction treatment was performed with H2, the formation of extremely small platinum clusters, incorporating no more than four Pt atoms was observed. The nuclearity of these clusters depends on the length of the hydrogen treatment. These Pt species remained strongly bonded to the dendrimer. Formation of larger platinum nanoparticles, with an average diameter of approximately 10 A, was finally observed after the deposition and drying of the H(2)PtCl(6)/G4OH nanocomposites on a gamma-Al(2)O(3) surface, suggesting that the formation of such nanoparticles may be related to the collapse of the dendrimer structure. The platinum nanoparticles formed appear to have high mobility because subsequent thermal treatment in O2/H2, used to remove the dendrimer component, led to further sintering.
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Affiliation(s)
- Oleg S Alexeev
- Department of Chemical Engineering, University of South Carolina, Columbia, South Carolina 29208, USA
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219
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N'Diaye AT, Bleikamp S, Feibelman PJ, Michely T. Two-dimensional Ir cluster lattice on a graphene moiré on Ir(111). PHYSICAL REVIEW LETTERS 2006; 97:215501. [PMID: 17155746 DOI: 10.1103/physrevlett.97.215501] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2006] [Indexed: 05/12/2023]
Abstract
Lattices of Ir clusters have been grown by vapor phase deposition on graphene moirés on Ir(111). The clusters are highly ordered, and spatially and thermally stable below 500 K. Their narrow size distribution is tunable from 4 to about 130 atoms. A model for cluster binding to the graphene is presented based on scanning tunneling microscopy and density functional theory. The proposed binding mechanism suggests that similar cluster lattices might be grown of materials other than Ir.
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Affiliation(s)
- Alpha T N'Diaye
- I. Physikalisches Institut, RWTH Aachen, 52056 Aachen, Germany.
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220
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Aikens CM, Schatz GC. TDDFT Studies of Absorption and SERS Spectra of Pyridine Interacting with Au20. J Phys Chem A 2006; 110:13317-24. [PMID: 17149852 DOI: 10.1021/jp065206m] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
We present time dependent density functional theory (TDDFT) calculations for a tetrahedral Au20 complex interacting with pyridine for the purpose of modeling absorption and surface enhanced Raman scattering, with emphasis on chemical and electrodynamic enhancement effects. These calculations are done using the ADF code with the BP86 functional, the zeroth-order regular approximation and with the resonant electronic response modeled using a short time approximation expression for the perturbed density matrix, with a damping factor that is empirically chosen. The absorption spectrum of bare Au20 shows strong intraband (sp-sp) and interband (sp-d) coupling with a low-energy peak at 2.89 eV that is mostly intraband and other peaks at 3.94 and 4.70 eV that have mixed intra- and interband character. SERS spectra are calculated for pyridine/Au20 for both vertex (V) and surface (S) configurations at their respective lowest energy absorption maxima (near 2.89 eV), and we find that the V configuration has higher intensities that correspond to SERS enhancements of 10(3)-10(4), whereas S has an enhancement of 10(2)-10(3). These enhancement values are significantly lower than the analogous results for pyridine/Ag20 primarily because of reduced oscillator strength associated with the intraband transition in Au20. Decomposition of the pyridine/Au20 enhancement factor into chemical and electromagnetic contributions (through an analysis of the static SERS intensities) shows enhanced chemical enhancements compared to Ag20 but reduced electromagnetic enhancements.
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Affiliation(s)
- Christine M Aikens
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, USA
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221
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Lim DC, Lopez-Salido I, Dietsche R, Bubek M, Kim YD. Electronic and chemical properties of supported Au nanoparticles. Chem Phys 2006. [DOI: 10.1016/j.chemphys.2006.09.025] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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222
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Wang Y, Gong XG. First-principles study of interaction of cluster Au32 with CO, H2, and O2. J Chem Phys 2006; 125:124703. [PMID: 17014196 DOI: 10.1063/1.2352749] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
First-principles calculations are performed to study the interaction of cluster Au(32) with small molecules, such as CO, H(2), and O(2). The cagelike Au(32)(I(h)) shows a higher chemical inertness than the amorphous Au(32)(C(1)) with respect to the interaction with small molecules CO, H(2), and O(2). H(2) can only be physically adsorbed on Au(32)(I(h)), while it can be dissociatively chemisorbed on Au(32)(C(1)). Although CO can be chemically adsorbed on Au(32)(I(h)) and Au(32)(C(1)) with one electron transferred from Au(32) to the antibonding pi* orbit of CO, it is bound more strongly on Au(32)(C(1)) than on Au(32)(I(h)). Spin polarized and spin nonpolarized calculations result almost identical ground state structures of Au(32)(I(h))-O(2) and Au(32)(C(1))-O(2), in which O(2) is dissociatively chemisorbed.
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Affiliation(s)
- Yao Wang
- Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China
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223
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Kielbassa S, Häbich A, Schnaidt J, Bansmann J, Weigl F, Boyen HG, Ziemann P, Behm RJ. On the morphology and stability of Au nanoparticles on TiO2(110) prepared from micelle-stabilized precursors. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2006; 22:7873-80. [PMID: 16922577 DOI: 10.1021/la0610102] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The morphology and stability of well-ordered, nanostructured Au/TiO2(110) surfaces, prepared by deposition of Au loaded micelles on TiO2(110) substrates and subsequent oxidative removal of the polymer shell in an oxygen plasma, was investigated by noncontact AFM, SEM and XPS. The resulting arrays of Au nanoparticles (particle sizes 1-5 nm) form a nearly hexagonal pattern with well-defined interparticle distances and a narrow particle size distribution. Particle size and particle separation can be controlled independently by varying the Au loading and the block-copolymers in the micelle shell. The oxygen plasma treatment does not affect the size and distance of the Au nanoparticles; the latter are fully metallic after subsequent UHV annealing (400 degrees C). The particles are stable under typical CO oxidation reaction conditions, up to at least 200 degrees C, making these surfaces ideally suited as defined model systems for catalytic studies. Significant changes in the height distributions of the Au nanoparticles are found upon 400 degrees C annealing in O2. For adlayers with small interparticle distances, this leads to a bimodal particle size distribution, which together with the preservation of the lateral order points to Ostwald ripening.
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Affiliation(s)
- Stefan Kielbassa
- Department of Surface Chemistry and Catalysis, University of Ulm, D-89069 Ulm, Germany
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224
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Zhao GF, Zeng Z. Geometrical and electronic structures of AumAgn (2⩽m+n⩽8). J Chem Phys 2006; 125:014303. [PMID: 16863294 DOI: 10.1063/1.2210470] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The structural and electronic properties of Au(m)Ag(n) binary clusters (2 < or = m + n < or = 8) have been investigated by density functional theory with relativistic effective core potentials. The results indicate that Au atoms tend to occupy the surface of Au(m)Ag(n) clusters (n > or = 2 and m > or = 2). As a result, segregation of small or big bimetallic clusters can be explained according to the atomic mass. The binding energies of the most stable Au(m)Ag(n) clusters increase with increasing m+n. The vertical ionization potentials of the most stable Au(m)Ag(n) clusters show odd-even oscillations with changing m+n. The possible dissociation channels of the clusters considered are also discussed.
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Affiliation(s)
- G F Zhao
- Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China
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225
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Zin MT, Yip HL, Wong NY, Ma H, Jen AKY. Arrays of covalently bonded single gold nanoparticles on thiolated molecular assemblies. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2006; 22:6346-51. [PMID: 16800697 DOI: 10.1021/la053256x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
A simple approach to form arrays of covalently bonded single gold nanoparticles (AuNPs) is demonstrated. Asymmetric molecular assemblies composed of two layers of rigid aromatic molecules with different structures, arranged in hexagonal arrays on a template produced by edge-spreading lithography, are used to guide the assembly of AuNPs. Arrays of single AuNPs are achieved by taking advantage of the interplay of electrostatic interactions and covalent bonding in conjunction with the positional constraint on the template. Schiff base chemistry is highlighted in the surface chemical reaction to selectively modify nanoscale surface features with high yield.
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Affiliation(s)
- Melvin T Zin
- Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195-2120, USA
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226
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Barnard AS, Curtiss LA. Predicting the Shape and Structure of Face-Centered Cubic Gold Nanocrystals Smaller than 3 nm. Chemphyschem 2006; 7:1544-53. [PMID: 16755641 DOI: 10.1002/cphc.200600107] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Although a number of computational studies have examined the relative stability of icosahedral and decahedral gold clusters from 1 to 3 nm in size, few studies have focussed on the variety of face-centered cubic (fcc) nanoparticles in this size regime. In most cases small fcc gold particles are assumed to adopt the truncated octahedral shape, but in light of the fact that the shape and structure of gold nanoparticles is known to vary, the relative stability of fcc polyhedra may change with size. Presented here are results of first-principles calculations investigating the preferred shape of gold particles less than 3 nm in size. Our results indicate that the equilibrium shape of fcc gold nanoparticles less than 1 nm is the cuboctahedron, but this shape rapidly becomes energetically unstable with respect to the truncated octahedron, octahedron and truncated cube shapes as the size increases.
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Affiliation(s)
- Amanda S Barnard
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK.
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227
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Lim DC, Lopez-Salido I, Dietsche R, Bubek M, Kim YD. Size-Selectivity in the Oxidation Behaviors of Au Nanoparticles. Angew Chem Int Ed Engl 2006. [DOI: 10.1002/ange.200504098] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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228
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Lim DC, Lopez-Salido I, Dietsche R, Bubek M, Kim YD. Size-Selectivity in the Oxidation Behaviors of Au Nanoparticles. Angew Chem Int Ed Engl 2006; 45:2413-5. [PMID: 16521146 DOI: 10.1002/anie.200504098] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Dong Chan Lim
- Fachbereich Physik, Universität Konstanz, Universitätsstrasse 10, 78457 Konstanz, Germany
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229
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Wang B, Chen K, Jiang S, Reincke F, Tong W, Wang D, Gao C. Chitosan-Mediated Synthesis of Gold Nanoparticles on Patterned Poly(dimethylsiloxane) Surfaces. Biomacromolecules 2006; 7:1203-9. [PMID: 16602739 DOI: 10.1021/bm060030f] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Synthesis of gold nanoparticles on surfaces has been accomplished by the incubation of poly(dimethylsiloxane) (PDMS) films in tetrachloroauric(III) acid and chitosan solution at room temperature and 4 degrees C. One important point in the present study is that the synthesis selectively occurred on the PDMS surface. These observations are substantially different from the reaction in solution, in which no particles can be formed at room temperature. Computation of surface plasmon bands (SPBs) based on Mie theory suggests that the particles are partially coated by chitosan molecules, and the experimental results confirm the theoretical calculations. The proposed mechanism is that chitosan molecules adsorbed or printed on the PDMS surfaces act as reducing/stabilizing agents. Furthermore, PDMS films patterned with chitosan could induce localized synthesis of gold nanoparticles in regions capped with chitosan only. In this way, colloidal patterns were fabricated on the surfaces with high spatial selectivity simultaneously with the synthesis of the particles. Surface-induced fluorescence quenching was observed in the regions capped with gold nanoparticles as well.
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Affiliation(s)
- Bo Wang
- Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, P. R. China
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230
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Montejano-Carrizales JM, Rodríguez-López JL, Pal U, Miki-Yoshida M, José-Yacamán M. The completion of the platonic atomic polyhedra: the dodecahedron. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2006; 2:351-5. [PMID: 17193048 DOI: 10.1002/smll.200500362] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
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231
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Zou JJ, Liu CJ, Zhang YP. Control of the metal-support interface of NiO-loaded photocatalysts via cold plasma treatment. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2006; 22:2334-9. [PMID: 16489826 DOI: 10.1021/la052135u] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
NiO-loaded semiconductors have been extensively used as the photocatalysts for water splitting. The metal-support interface is an important factor affecting the efficiency. In the present work, the pretreatment methods were studied to produce a more desirable metal-support interface using Ta2O5 and ZrO2 as the support. The traditional method includes a thermal decomposition, reduction at 773 K, and oxidation at 473 K (R773-O473). The thermal decomposition of Ni(NO3)2 makes the Ni atoms migrate into the bulk of the supports, resulting in a diffused interfacial region. Alternatively, a cold plasma treatment was used to replace the thermal decomposition. Metal salts are quickly decomposed by glow discharge plasma treatment at room temperature, avoiding the thermal diffusion of Ni atoms. With the sequent R773-O473 treatment, a clean metal-support interface is produced. Moreover, the metal particles have optimal shapes with a larger surface. In photocatalysis, the clean metal-support interface is more favorable for the charge separation and transfer, and the increased metal surface provides more active sites. NiO/Ta2O5 and NiO/ZrO2 prepared with the plasma treatment exhibit higher activity for photocatalytic hydrogen generation from pure water and methanol solution, respectively. This work shows the potential of cold plasma treatment in the preparation of metal-loaded catalysts and nanostructured materials.
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Affiliation(s)
- Ji-Jun Zou
- Key Laboratory for Green Chemical Technology, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, People's Republic of China
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232
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Tsukuda T. ELECTROCHEMISTRY 2006; 74:346-350. [DOI: 10.5796/electrochemistry.74.346] [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] Open
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233
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Tunc I, Demirok UK, Suzer S, Correa-Duatre MA, Liz-Marzan LM. Charging/Discharging of Au (Core)/Silica (Shell) Nanoparticles as Revealed by XPS. J Phys Chem B 2005; 109:24182-4. [PMID: 16375410 DOI: 10.1021/jp055614a] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
By recording XPS spectra while applying external voltage stress to the sample rod, we can control the extent of charging developed on core-shell-type gold nanoparticles deposited on a copper substrate, in both steady-state and time-resolved fashions. The charging manifests itself as a shift in the measured binding energy of the corresponding XPS peak. Whereas the bare gold nanoparticles exhibit no measurable binding energy shift in the Au 4f peaks, both the Au 4f and the Si 2p peaks exhibit significant and highly correlated (in time and magnitude) shifts in the case of gold (core)/silica (shell) nanoparticles. Using the shift in the Au 4f peaks, the capacitance of the 15-nm gold (core)/6-nm silica (shell) nanoparticle/nanocapacitor is estimated as 60 aF. It is further estimated that, in the fully charged situation, only 1 in 1000 silicon dioxide units in the shell carries a positive charge during our XPS analysis. Our simple method of controlling the charging, by application of an external voltage stress during XPS analysis, enables us to detect, locate, and quantify the charges developed on surface structures in a completely noncontact fashion.
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Affiliation(s)
- Ilknur Tunc
- Chemistry Department and the Laboratory for Advanced Functional Materials, Bilkent University, 06800 Ankara, Turkey
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234
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Lee S, Fan C, Wu T, Anderson SL. Cluster size effects on CO oxidation activity, adsorbate affinity, and temporal behavior of model Aun∕TiO2 catalysts. J Chem Phys 2005; 123:124710. [PMID: 16392514 DOI: 10.1063/1.2035098] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Model catalysts were prepared by deposition of size-selected Au(n) (n = 1-7) on rutile TiO2(110), and characterized by a combination of electron spectroscopy, ion scattering, temperature-programmed desorption, and pulse-dosing mass spectrometry. CO oxidation activity was found to vary strongly with deposited cluster size, with significant activity appearing at Au3. Activity is not obviously correlated with affinity for CO, or with cluster morphology, but is strongly correlated with the clusters' ability to bind oxygen (during O2 exposure) on top of the gold. The temporal dependence of CO2 evolution in reaction of O2 pre-exposed samples with CO pulses shows an interesting cluster size dependence. For Au5 and Au6, the peak CO2 production is coincident with the peak CO flux, but for Au3, Au4, and Au7, there are significant induction periods for CO2 evolution. In addition, it is observed that some of the most active cluster sizes have the slowest CO2 evolution rates. Several mechanistic scenarios capable of accounting for the observations are laid out.
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Affiliation(s)
- Sungsik Lee
- Department of Chemistry, University of Utah, 315 S. 1400 E. RM Dock, Salt Lake City, Utah 84112-0850, USA
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235
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236
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Balasubramanian R, Guo R, Mills AJ, Murray RW. Reaction of Au(55)(PPh(3))(12)Cl(6) with thiols yields thiolate monolayer protected Au(75) clusters. J Am Chem Soc 2005; 127:8126-32. [PMID: 15926840 DOI: 10.1021/ja050793v] [Citation(s) in RCA: 152] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This paper describes the reaction of the phosphine-protected Au nanoparticle Au(55)(PPh(3))(12)Cl(6) (1, "Au55") with hexanethiol (2) and other thiols. The voltammetry of the reaction product 2 displays a well-defined pattern of peaks qualitatively reminiscent of Au(38) nanoparticles, but with quite different spacing (0.74 +/- 0.01 V) between the potentials of initial oxidation and reduction steps (electrochemical gap). Correction of this "molecule-like" gap for charging energy indicates a HOMO-LUMO gap energy of about 0.47 V. Voltammetry of the products (3 and 4) of reaction of 1 with C(3)H(7)SH and PhC(2)H(4)SH, respectively, is similar. Laser desorption/ionization mass spectrometry (LDI-MS) shows that 2 contains a high proportion of a core mass in the 14-15 kDa range, which is proposed to be Au(75). UV-vis spectra of 2-4 are relatively featureless, similar to previous reports of thiolate-protected Au(75) nanoparticles. HPLC analysis of 2 shows a Au(75) content of ca. 73%; the electrochemical purity estimate is also high, about 55%. Combining the mass spectrometric result with thermogravimetric analysis of 2 leads to a preliminary formulation Au(75)(SC(6)H(13))(40). This Au(75) synthesis complements a previous Brust-type synthesis and is unusual in the apparent provocation in the reaction of an increase in core size.
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Affiliation(s)
- Ramjee Balasubramanian
- Kenan Laboratories of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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237
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Chou J, Zhang S, Sun S, McFarland EW. Benzene Formation at 70 °C by Coupling of Propylene on Supported Pd Nanoclusters. Angew Chem Int Ed Engl 2005; 44:4735-9. [PMID: 15984040 DOI: 10.1002/anie.200500022] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Ju Chou
- Department of Chemistry and Physics, Southeastern Louisiana University, Hammond, LA 70402, USA
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238
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Chou J, Zhang S, Sun S, McFarland EW. Benzene Formation at 70 °C by Coupling of Propylene on Supported Pd Nanoclusters. Angew Chem Int Ed Engl 2005. [DOI: 10.1002/ange.200500022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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239
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Li X, Göring P, Pippel E, Steinhart M, Kim DH, Knoll W. Fabrication of Au/Titania Composite Nanodot Arrays from Au-Loaded Block Copolymer Micellar Films. Macromol Rapid Commun 2005. [DOI: 10.1002/marc.200500193] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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240
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Crespo-Biel O, Jukovic A, Karlsson M, Reinhoudt DN, Huskens J. Multivalent aggregation of cyclodextrin gold nanoparticles and adamantyl-terminated guest molecules. Isr J Chem 2005. [DOI: 10.1560/af3p-k2a6-mdck-1678] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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241
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Tunc I, Suzer S, Correa-Duarte MA, Liz-Marzán LM. XPS Characterization of Au (Core)/SiO2 (Shell) Nanoparticles. J Phys Chem B 2005; 109:7597-600. [PMID: 16851877 DOI: 10.1021/jp050767j] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Core-shell nanoparticles with ca. 15-nm gold core and 6-nm silica shell were prepared and characterized by XPS. The Au/Si atomic ratio determined by XPS is independent of the electron takeoff angle because of the concentric spherical shape of the nanoparticles. The formula given by Wertheim and DiCenzo (Phys. Rev. B 1988, 37, 844) for spherical nanoparticles and the modified one by Yang et. al. (J. Appl. Phys. 2005, 97, 024303) for core-shell nanoparticles are used to correlate the XPS-derived composition with the geometry of the nanoparticles only after significantly modifying either the bulk density of the silica shell or the attenuation length of the photoelectrons.
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242
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Gillet JN, Meunier M. General Equation for Size Nanocharacterization of the Core−Shell Nanoparticles by X-ray Photoelectron Spectroscopy. J Phys Chem B 2005; 109:8733-7. [PMID: 16852034 DOI: 10.1021/jp044322r] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Nanocharacterization is essential for nanoengineering of new types of core-shell (c-s) nanoparticles, which can be used to design new devices for photonics, electronics, catalysis, medicine, etc. X-ray photoelectron spectroscopy (XPS) has been widely used to study the elemental composition of the c-s nanoparticles. However, the physical and chemical properties of a c-s nanoparticle dramatically depend on the sizes of its core and shell. We therefore propose a general equation for the XPS intensity of a c-s nanoparticle, which is based on an analytical model. With this equation, XPS can now also be used for nanocharacterization of the core and shell sizes of the c-s nanoparticles (with a diameter smaller than or equal to the XPS probing depth of approximately 10 nm). To validate the new equation with experimental XPS data, we first determine the average shell thickness of a group of c-s nanoparticles by comparing the XPS intensity of reference bare cores to that of the c-s nanoparticles. Then we study the growth kinetics of the cores and shells of another group of c-s nanoparticles where the shells are obtained by oxidation.
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Affiliation(s)
- Jean-Numa Gillet
- Laser Processing Laboratory, Department of Engineering Physics, Ecole Polytechnique de Montréal, C.P. 6079, succ. Centre-ville, Montréal, Québec H3C 3A7, Canada.
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243
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Wannere CS, Corminboeuf C, Wang ZX, Wodrich MD, King RB, Schleyer PVR. Evidence for d Orbital Aromaticity in Square Planar Coinage Metal Clusters. J Am Chem Soc 2005; 127:5701-5. [PMID: 15826211 DOI: 10.1021/ja042716q] [Citation(s) in RCA: 136] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Quantitative evidence for the existence of aromaticity involving the d orbitals of transition metals is provided for the first time. The doubly bridged square planar (D(4)(h)()) coinage metal clusters (M(4)Li(2), M = Cu (1), Ag (2), and Au (3)) are characterized as aromatic by their substantial nucleus independent chemical shifts (NICS) values in the centers (-14.5, -14.1, and -18.6, respectively). Nevertheless, the participation of p orbitals in the bonding (and cyclic electron delocalization) of 1-3 is negligible. Instead, these clusters benefit strongly from the delocalization of d and to some extent s orbitals. The same conclusion applies to Tsipis and Tsipis' H-bridged D(4)(h)() Cu(4)H(4) ring (4). Canonical MO-NICS analysis of structures 1-3 shows the total diatropic d orbital contributions to the total NICS to be substantial, although the individual contributions of the five sets of filled d orbitals vary. The d orbital aromaticity of Cu(4)Li(2) also is indicated by its atomization energy, 243.2 kcal/mol, which is larger than Boldyrev's doubly (sigma and pi) aromatic Al(4)Li(2) (215.9 kcal/mol).
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Affiliation(s)
- Chaitanya S Wannere
- Center for Computational Chemistry and Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
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244
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Yuan DW, Wang Y, Zeng Z. Geometric, electronic, and bonding properties of AuNM (N=1–7, M=Ni, Pd, Pt) clusters. J Chem Phys 2005; 122:114310. [PMID: 15836218 DOI: 10.1063/1.1862239] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Employing first-principles methods, based on density functional theory, we report the ground state geometric and electronic structures of gold clusters doped with platinum group atoms, Au(N)M (N = 1-7, M = Ni, Pd, Pt). The stability and electronic properties of Ni-doped gold clusters are similar to that of pure gold clusters with an enhancement of bond strength. Due to the strong d-d or s-d interplay between impurities and gold atoms originating in the relativistic effects and unique properties of dopant delocalized s-electrons in Pd- and Pt-doped gold clusters, the dopant atoms markedly change the geometric and electronic properties of gold clusters, and stronger bond energies are found in Pt-doped clusters. The Mulliken populations analysis of impurities and detailed decompositions of bond energies as well as a variety of density of states of the most stable dopant gold clusters are given to understand the different effects of individual dopant atom on bonding and electronic properties of dopant gold clusters. From the electronic properties of dopant gold clusters, the different chemical reactivity toward O(2), CO, or NO molecule is predicted in transition metal-doped gold clusters compared to pure gold clusters.
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Affiliation(s)
- D W Yuan
- Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei, People's Republic of China
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245
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Potemkin II, Möller M. Microphase Separation in Ultrathin Films of Diblock Copolymers with Variable Stickiness of One of the Blocks to the Surface. Macromolecules 2005. [DOI: 10.1021/ma047576j] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Igor I. Potemkin
- Physics Department, Moscow State University, Moscow 119992, Russia, and Institut für Technische Chemie und Makromolekulare Chemie, RWTH Aachen, D-52062 Aachen, Germany
| | - Martin Möller
- Physics Department, Moscow State University, Moscow 119992, Russia, and Institut für Technische Chemie und Makromolekulare Chemie, RWTH Aachen, D-52062 Aachen, Germany
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246
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Shi F, Zhang Q, Ma Y, He Y, Deng Y. From CO Oxidation to CO2Activation: An Unexpected Catalytic Activity of Polymer-Supported Nanogold. J Am Chem Soc 2005; 127:4182-3. [PMID: 15783195 DOI: 10.1021/ja042207o] [Citation(s) in RCA: 212] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A simple, clean, safe, and reproducible catalyst system, polymer-supported nanogold, was successfully developed for the fixation of CO2 to cyclic carbonate and for the carbonylation of amines to disubstituted ureas with unprecedented catalytic activity (TOF > 50 000 mol/mol/h and TOFP approximately 3000 mol/mol/h, respectively). To the best of our knowledge, it was the first to report that nanogold catalysts have exclusive catalytic activity for activation of carbon dioxide, and that the catalytic activity of the polymer-immobilized nanogold catalysts could be controlled by the particle size of the nanogold.
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Affiliation(s)
- Feng Shi
- Centre for Green Chemistry and Catalysis, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China
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247
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Plaza JL, Chen Y, Jacke S, Palmer RE. Nanoparticle arrays patterned by electron-beam writing: structure, composition, and electrical properties. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:1556-1559. [PMID: 15697307 DOI: 10.1021/la047777g] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Direct electron beam writing in nanoparticle films is employed to create nanoscale wires between prepatterned gold electrodes on SiO(2)/Si wafers. Characterization of these nanowires using AFM, SEM, and EDX reveals a core/sheath morphology, where a gold-rich core is surrounded by a sheath which is mainly of carbon. Z-contrast STEM images indicate that the central core consists of a distribution of metal cores in a carbon network. The results suggest that the nanoparticle network is created through cross-linking of the ligands of adjacent particles. The high resistivities obtained in conductivity measurements are consistent with this picture. The work illustrates the ability to generate patterned nanoparticle arrays which can be addressed electrically.
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Affiliation(s)
- Jose L Plaza
- Nanoscale Physics Research Laboratory, School of Physics and Astronomy, The University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
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248
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249
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Boyen HG, Ethirajan A, Kästle G, Weigl F, Ziemann P, Schmid G, Garnier MG, Büttner M, Oelhafen P. Alloy formation of supported gold nanoparticles at their transition from clusters to solids: does size matter? PHYSICAL REVIEW LETTERS 2005; 94:016804. [PMID: 15698114 DOI: 10.1103/physrevlett.94.016804] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2004] [Indexed: 05/24/2023]
Abstract
Gold nanoclusters of a size approaching the molecular limit (<3 nm) were prepared on Si substrates in order to study alloy formation on the nanometer scale. For this purpose, indium atoms are deposited on top of the gold particles at room temperature and the formation of AuIn(2) is studied by x-ray photoelectron spectroscopy in situ. It is observed that the alloy formation takes place independent of whether the particles electronically are in an insulating molecular or in a metallic state. Most important, however, closed packed full-shell clusters containing 55 Au atoms are found to exhibit an outstanding stability against alloying despite a large negative heat of formation of the bulk Au-In system. Thus, Au(55) clusters may play a significant role in the design of nanoscaled devices where chemical inertness is of crucial importance.
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Affiliation(s)
- H-G Boyen
- Abteilung Festkörperphysik, Universität Ulm, D-89069 Ulm, Germany
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250
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Schmid G, Emmrich E, Majoral JP, Caminade AM. The behavior of Au55 nanoclusters on and in thiol-terminated dendrimer monolayers. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2005; 1:73-5. [PMID: 17193351 DOI: 10.1002/smll.200400018] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Affiliation(s)
- Günter Schmid
- Institut für Anorganische Chemie der Universität Duisburg-Essen, Universitätsstrasse 5-7, 45117 Essen, Germany.
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