Bibliographies thématiques / Supported nanoclusters

Littérature scientifique sur le sujet « Supported nanoclusters »

Auteur : Grafiati
Publié le 11 mars 2023

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Articles de revues sur le sujet "Supported nanoclusters"

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Montejo-Alvaro, Fernando, Jesus A. Martínez-Espinosa, Hugo Rojas-Chávez, Diana C. Navarro-Ibarra, Heriberto Cruz-Martínez et Dora I. Medina. « CO2 Adsorption over 3d Transition-Metal Nanoclusters Supported on Pyridinic N3-Doped Graphene : A DFT Investigation ». Materials 15, no 17 (4 septembre 2022) : 6136. http://dx.doi.org/10.3390/ma15176136.

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CO2 adsorption on bare 3d transition-metal nanoclusters and 3d transition-metal nanoclusters supported on pyridinic N3-doped graphene (PNG) was investigated by employing the density functional theory. First, the interaction of Co13 and Cu13 with PNG was analyzed by spin densities, interaction energies, charge transfers, and HUMO-LUMO gaps. According to the interaction energies, the Co13 nanocluster was adsorbed more efficiently than Cu13 on the PNG. The charge transfer indicated that the Co13 nanocluster donated more charges to the PNG nanoflake than the Cu13 nanocluster. The HUMO-LUMO gap calculations showed that the PNG improved the chemical reactivity of both Co13 and Cu13 nanoclusters. When the CO2 was adsorbed on the bare 3d transition-metal nanoclusters and 3d transition-metal nanoclusters supported on the PNG, it experienced a bond elongation and angle bending in both systems. In addition, the charge transfer from the nanoclusters to the CO2 molecule was observed. This study proved that Co13/PNG and Cu13/PNG composites are adequate candidates for CO2 adsorption and activation.
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Montejo-Alvaro, Fernando, Diego González-Quijano, Jorge A. Valmont-Pineda, Hugo Rojas-Chávez, José M. Juárez-García, Dora I. Medina et Heriberto Cruz-Martínez. « CO2 Adsorption on PtCu Sub-Nanoclusters Deposited on Pyridinic N-Doped Graphene : A DFT Investigation ». Materials 14, no 24 (10 décembre 2021) : 7619. http://dx.doi.org/10.3390/ma14247619.

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To reduce the CO2 concentration in the atmosphere, its conversion to different value-added chemicals plays a very important role. Nevertheless, the stable nature of this molecule limits its conversion. Therefore, the design of highly efficient and selective catalysts for the conversion of CO2 to value-added chemicals is required. Hence, in this work, the CO2 adsorption on Pt4-xCux (x = 0–4) sub-nanoclusters deposited on pyridinic N-doped graphene (PNG) was studied using the density functional theory. First, the stability of Pt4-xCux (x = 0–4) sub-nanoclusters supported on PNG was analyzed. Subsequently, the CO2 adsorption on Pt4-xCux (x = 0–4) sub-nanoclusters deposited on PNG was computed. According to the binding energies of the Pt4-xCux (x = 0–4) sub-nanoclusters on PNG, it was observed that PNG is a good material to stabilize the Pt4-xCux (x = 0–4) sub-nanoclusters. In addition, charge transfer occurred from Pt4-xCux (x = 0–4) sub-nanoclusters to the PNG. When the CO2 molecule was adsorbed on the Pt4-xCux (x = 0–4) sub-nanoclusters supported on the PNG, the CO2 underwent a bond length elongation and variations in what bending angle is concerned. In addition, the charge transfer from Pt4-xCux (x = 0–4) sub-nanoclusters supported on PNG to the CO2 molecule was observed, which suggests the activation of the CO2 molecule. These results proved that Pt4-xCux (x = 0–4) sub-nanoclusters supported on PNG are adequate candidates for CO2 adsorption and activation.
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Spontak, Richard J., Janet L. Burns et Charles J. Echer. « Morphological studies of nanoclusters on grid-supported polymer thin films ». Journal of Materials Research 7, no 9 (septembre 1992) : 2593–98. http://dx.doi.org/10.1557/jmr.1992.2593.

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Modification of substrates by controlled deposition of nanometer-size particulates (nanoclusters) is an efficient means of fabricating materials designed for applications in which specific surface interactions play a vital role (e.g., molecular catalysis and microelectronics). We have found that highly dispersed nanoclusters form on thin films of poly(siloxaneimide) (PSI) copolymers supported on copper transmission electron microscopy (TEM) grids when subjected to long anneals at elevated temperatures. In this note, we report on the composition and source of these anomalous nanoclusters, as determined by a variety of electron microscopical techniques. Spectra obtained with parallel electron energy-loss spectroscopy (PEELS) indicate that these particulates, which typically measure 4–18 nm in diameter, are composed of copper with a mean valence of +1. Electron microdiffraction patterns reveal that the nanoclusters are polycrystalline, possessing lattice spacings similar to those of Cu2O. Mechanistic routes of formation are suggested based on experimental design, and factors influencing formation are also described.
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Yu, Weiyong, Hanfan Liu et Xiaohua An. « Novel catalytic properties of supported metal nanoclusters ». Journal of Molecular Catalysis A : Chemical 129, no 1 (mars 1998) : L9—L13. http://dx.doi.org/10.1016/s1381-1169(97)00306-3.

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Amitouche, F., S. Bouarab et C. Demangeat. « Supported magnetic Pd nanoclusters on Ag(001) ». Catalysis Today 89, no 3 (mars 2004) : 375–78. http://dx.doi.org/10.1016/j.cattod.2003.12.011.

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Lünskens, Tobias, Philipp Heister, Martin Thämer, Constantin A. Walenta, Aras Kartouzian et Ulrich Heiz. « Plasmons in supported size-selected silver nanoclusters ». Physical Chemistry Chemical Physics 17, no 27 (2015) : 17541–44. http://dx.doi.org/10.1039/c5cp01582k.

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Palmer, Richard. « Atomic Structure and Mass-Production of Supported Size-Selected Nanoclusters ». Acta Crystallographica Section A Foundations and Advances 70, a1 (5 août 2014) : C733. http://dx.doi.org/10.1107/s2053273314092663.

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Deposition of size-selected nanoclusters assembled from atoms in the gas phase is a novel route to the fabrication of <10nm surface features. I will focus on the creation and atomic structure of monodispersed metal cluster arrays which enable new model catalysts and protein biochips. The atomic structure of the clusters – previously the province of theory - is revealed experimentally [1] by aberration-corrected scanning transmission electron microscopy (STEM) in the HAADF imaging regime; we can "count" atoms and obtain 3D information not just 2D projections. Results include mass spectrometry of thiolated Au clusters, adatom dynamics on Au923 magic-number nanoclusters [2], first atomic imaging results for Au55 and Au20 and a method to explore the potential energy landscape of (Au923) clusters via cluster transformations [3], presenting a reference system for theory. A new kind of cluster beam source, to allow super-abundant generation of size-selected nanoclusters, will also be demonstrated.
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Bazylewski, P., D. W. Boukhvalov, A. I. Kukharenko, E. Z. Kurmaev, A. Hunt, A. Moewes, Y. H. Lee, S. O. Cholakh et G. S. Chang. « The characterization of Co-nanoparticles supported on graphene ». RSC Advances 5, no 92 (2015) : 75600–75606. http://dx.doi.org/10.1039/c5ra12893e.

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Karanjit, Sangita, Ayumu Tamura, Masaya Kashihara, Kazuki Ushiyama, Lok Kumar Shrestha, Katsuhiko Ariga, Atsushi Nakayama et Kosuke Namba. « Hydrotalcite-Supported Ag/Pd Bimetallic Nanoclusters Catalyzed Oxidation and One-Pot Aldol Reaction in Water ». Catalysts 10, no 10 (29 septembre 2020) : 1120. http://dx.doi.org/10.3390/catal10101120.

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A highly active hydrotalcite-supported Ag/Pd bimetallic nanocluster catalyst has been developed by a simple, easy and safe chemical reduction method. The catalyst was characterized by high-resolution transmission electron microscopy (HR-TEM), which revealed very small (3.2 ± 0.7 nm) nanoclusters with a narrow size distribution. The bimetallic Ag/Pd catalyst showed strong cooperation between Ag and Pd for the alcohol oxidation reaction. The developed catalyst provided an efficient and environmentally friendly method for alcohol oxidation and one-pot cross-aldol condensation in water. A broad scope of α,β-unsaturated ketones with good to excellent yields were obtained under very mild conditions. This catalytic system offers an easy preparation method with a simple recovery process, good activity and reusability of up to five cycles without significant loss in the catalytic activity.
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BORMAN, V. D., P. V. BORISYUK, I. V. TRONIN, V. N. TRONIN, V. I. TROYAN, M. A. PUSHKIN et O. S. VASILIEV. « MELTING POINT AND LATTICE PARAMETER SHIFT IN SUPPORTED METAL NANOCLUSTERS ». International Journal of Modern Physics B 23, no 19 (30 juillet 2009) : 3903–11. http://dx.doi.org/10.1142/s0217979209053321.

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The dependencies of the melting point and the lattice parameter of supported metal nanoclusters as functions of clusters height are theoretically investigated in the framework of the uniform approach. The vacancy mechanism describing the melting point and the lattice parameter shifts in nanoclusters with decrease in their sizes is proposed. It is shown that under the high vacuum conditions (p < 10-7 torr ) the essential role in clusters melting point and lattice parameter shifts is played by van der Waals forces of cluster–substrate interaction. The proposed model satisfactorily accounts for the experimental data.
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Thèses sur le sujet "Supported nanoclusters"

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Burkardt, Sven. « Oxide and oxide supported nanoclusters on quasicrystals ». Berlin Logos-Verl, 2009. http://d-nb.info/999419471/04.

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Teng, Die. « Computational studies of transition metal nanoclusters on metal-supported graphene moiré ». Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/51830.

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The graphene moiré superstructure formed on Ru(0001) (g/Ru(0001)) has shown the potential as a template to self-assemble super-lattices of metal nanoparticles as model catalysts. To explore the possibility of rational catalyst design on g/Ru(0001), detailed density functional theory (DFT) calculations have been performed to investigate the adsorption and diffusion of Rh and Au adatoms on g/Ru(0001). The consequences of different hopping rates for cluster nucleation have been explored by performing Monte Carlo-based statistical analysis, which suggests that diffusing species other than adatoms need to be taken into account to develop an accurate description of cluster nucleation and growth on this surface. DFT calculations have also been carried out to investigate the adsorption and diffusion of 18 4d (Y-Ag) and 5d (La-Au) transition metal adatoms on g/Ru(0001). Given the necessity to study larger diffusing species than adatoms, DFT calculations have been performed to study the adsorption and diffusion of Rh and Au dimers and trimers on g/Ru(0001). It was shown that the mobility of Rh clusters decreases with the increase of cluster size, while for Au, dimers diffuse faster than monomers and trimers on the moiré surface. We then used a genetic algorithm combined with DFT calculations to predict the lowest energy structure of a Au8 cluster on g/Ru(0001). Our prediction leads us to propose that Au clusters aggregates through Oswald ripening with Au dimer being the major diffusing species. Finally, we examined the morphology of a Cu19 cluster on g/Cu(111) using MD simulations with COMB3 potential. We also studied the mobility of Cu clusters on g/Cu(111) at elevated temperatures. The analysis suggests that g/Cu(111) may not be a suitable substrate for the formation and growth of isolated Cu clusters. All these calculation results have provided us a better understanding and useful insights into the nucleation and growth mechanism of metal clusters on graphene moiré.
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Golfetto, Enrico. « Electronic structure and chemical reactivity of transition metals' pseudomorphic layers and supported nanoclusters ». Doctoral thesis, Università degli studi di Trieste, 2010. http://hdl.handle.net/10077/3580.

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2008/2009
The importance of heterogeneous catalysis in chemical industry and its economic impact in today‟s society motivate the continuous research effort in this field. Transition metals are among the main ingredients of commercial catalysts due to their chemical properties which depend on their surface morphological and electronic structure. It is well known that their catalytic properties can be further improved by tuning particle size in the nanometre range or by alloying different transition metals. Nowadays it is possible to predict the variation of surface chemical properties on the basis of the d-band centre energy position, which is actually considered as one of the most reliable depicters of chemical reactivity. This physical quantity cannot be easily accessed by experimental measurement and is typically calculated using a theoretical approach. A promising approach to establish an experimental relationship between electronic structure and chemical reactivity relies on the use of X-ray Photoelectron Spectroscopy with third generation synchrotron radiation sources. Indeed, the high resolution achieved in the recent years has allowed the identification of the contributions originated from bulk and surface atoms in the core level photoemission spectra,thus determining what is usually named Surface Core Level Shift (SCLS). It has been shown that SCLS is a valuable probe of surface electronic structure, since the core level binding energy of an atom depends strongly on the local structural and chemical environment. In this thesis, the electronic structure modification induced by reduced coordination, surface strain, atomic rearrangement and ligand effects are investigated in different systems by means of High Energy Resolution Core Level Spectroscopy experiments, on several systems with different complexity. Pseudomorphic states of Pd, grown on a Ru(0001) surface, have been studied by comparing the calculated d-band center shifts of the differently coordinated atoms to the measured core level shifts of the same species, finding a strong relationship between these two physical quantities. For two of structures (1- and 2-Pd MLs/Ru(0001)) we tested the chemical reactivity by exposing the surfaces to oxygen. The results confirmed the relationship between d-band center shift, CLS and chemical reactivity. A more complex system is the one composed by Pd nanoclusters on Single Walled Carbon NanoTubes (SWCNTs), Highly Ordered Pyrolythic Graphite (HOPG) and Ir supported graphene sheet. The most relevant feature is the formation of a high BE component in Pd 3d5/2 spectrum, induced by those Pd atoms coordinated with surface defects. This interpretation has been suggested by the comparison of experimental results with the calculations on Pd/HOPG core level shifts for many different atomic species. For Pd/SWCNTs we studied also the oxidation mechanisms, ranging on a wide spectrum of oxidation conditions. Our results confirm the presence of a 2D oxide phase, as previously found on Pd single crystal, with some different behaviour induced by the reduced size of our particle Finally, the growth mechanisms and the chemical reactivity of Pt nanoclusters, supported on a MgO thin film has been studied by both energy and time resolved x-ray photoemission spectroscopy. The CO oxidation reaction has been investigated for different temperatures and different clusters‟ size, resulting also in a deeper comprehansion of the clusters‟ morphology.
XXII Ciclo
1979
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Zhang, Man. « Design, synthesis, and evaluation of bioactive molecules ; Chiral polyvinylpyrrolidones supported Cu/Au nanoclusters catalyzed cyclization of 5-substituted nona-1,8-dien-5-ols ». Diss., Kansas State University, 2017. http://hdl.handle.net/2097/35470.

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Doctor of Philosophy
Department of Chemistry
Duy H. Hua
Small molecules are of great importance in drug discovery currently. The first three chapters discussed the design, synthesis and bio-evaluation of three different classes of small molecules and exploration of their biological targets. Triacsin C analogs were designed as long chain fatty acyl-CoA synthetase (ACSL) inhibitors for attenuating ischemia and reperfusion (I/R) injury. Oxadiazole derivatives were designed as T-type calcium channel inhibitors, which have potential application in the treatment of seizure and epilepsy. Tricyclic pyrone derivatives were reported as anti-Alzheimer lead compounds in previous research done by the Hua group. TP70 and CP2 were synthesized to explore their pharmacokinetics properties. Chapter 4 described chiral-substituted poly-N-vinylpyrrolidones (CSPVP) supported Cu/Au nanoclusters mediation of cyclization reaction of 5-substituted nona-1,8-dien-5-ols. A five-member cyclized lactone possessing a stereogenic tetrasubstituted carbon center was formed in a one-step Cu/Au nanoclusters-hydrogen peroxide oxidation reaction. This developed a novel and simple method to synthesize tetrasubstituted carbon stereogenic center. Drawbacks of the method in my initial study were low reaction yield and moderate enantioselectivity. The chemical yield and enantioselectivity have been significantly improved by introducing bulkier substitution in C3 and C4 positions of CSPVP according to the updates of ongoing research.
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Lacovig, Paolo. « Electronic structure, morphology and chemical reactivity of nanoclusters and low-dimensional systems : fast photoemission spectroscopy studies ». Doctoral thesis, Università degli studi di Trieste, 2010. http://hdl.handle.net/10077/3685.

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2008/2009
L'obiettivo di questa tesi è l'applicazione della spettroscopia di fotoemissione allo studio di nanoparticelle supportate e di sistemi a bassa dimensionalità. Ad una primo periodo dedicato allo sviluppo del rivelatore e del software per un nuovo analizzatore d'energia per elettroni installato presso la linea di luce SuperESCA ad Elettra, è seguita una fase durante la quale ho eseguito una serie di esperimenti mirati ad esplorare le potenzialità del nuovo apparato sperimentale. Il primo risultato ottenuto riguarda la comprensione della relazione che intercorre tra le variazioni della reattività chimica del sistema Pd/Ru(0001) e il numero degli strati di Pd cresciuti in modo pseudomorfico sul substrato di rutenio. La risoluzione temporale raggiunta con la nuova strumentazione ci ha permesso di studiare processi dinamici su una scala temporale fino ad ora inaccessibile per la spettroscopia di fotoemissione dai livelli di core: in particolare abbiamo studiato la crescita del grafene ad alta temperatura sulla superficie (111) dell'iridio e la reattività chimica di nanocluster di Pt supportati su MgO. Nel primo caso abbiamo messo in evidenza come la formazione del grafene proceda attraverso la nucleazione di nano-isole di carbonio che assumono una peculiare forma di cupola. Nel secondo caso siamo riusciti a seguire sia la dinamica del processo di adsorbimento di CO, sia la reazione CO + 1/2 O2 -> CO2 sulle nanoparticelle di Pt depositate su un film ultra-sottile di ossido di magnesio. Infine, abbiamo caratterizzato la morfologia di nanoparticelle di Pd, Pt, Rh e Au cresciute su diversi substrati a base di carbonio, in particolare grafite, nanotubi a parete singola e grafene. Tra i vari risultati abbiamo compreso come l'interazione metallo-substrato dipenda dalla dimensione delle nano-particelle e abbiamo evidenziato il ruolo centrale dei difetti del substrato nei processi di nucleazione e intercalazione.
The objective of this thesis is the application of photoelectron spectroscopy for the investigation of supported nanoclusters and low-dimensional systems. After a first stage devoted to the development of the detector and the software for the electron energy analyser installed on the SuperESCA beamline at Elettra, during the PhD project I've performed a series of experiments aimed to explore the capabilities of the new experimental apparatus. One of the first results concerns the understanding of the relation between the modifications in the chemical reactivity of the Pd/Ru(0001) system and the thickness of the pseudomorphically grown Pd overlayer. The temporal resolution achieved with the new experimental set-up allowed us to study dynamical processes on a new time scale, in particular the graphene growth process at high temperature on the Ir(111) surface and the chemical reactivity of Pt nanoclusters supported on MgO. In the former case, we discovered that graphene formation proceeds via preliminary nucleation of dome-shaped C nano-islands. In the second case, we succeded in following both the dynamics of CO adsorption process and the CO + 1/2 O2 -> CO2 reaction on Pt nanoclusters grown on a ultra-thin film of magnesium oxide. Finally, the morphology of Pd, Pt, Rh and Au nanoclusers grown on different carbon-based substrates (namely graphite, single-walled carbon nanotubes and graphene) has been characterized. Among the results we report the understanding of the dependence of the metal-substrate interaction on the cluster size and the role of defects in the nucleation and intercalation processes.
XXII Ciclo
1972
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PRADA, STEFANO. « Enhancing oxide surface reactivity by doping or nano-structuring ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2014. http://hdl.handle.net/10281/50011.

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Wide band-gap simple oxides are rather inert materials, which found applications in heterogeneous catalysis mainly as supports for active metal nanoparticles. This thesis investigates tailored modifications of the oxide characteristics aimed at making these substrates more reactive in catalytic processes. In particular we are interested in engineering the charge transfer with supported metal catalysts in order to enhance their activity and selectivity. By using first principles calculations in the framework of the density functional theory, we have explored two main routes in this field: 1) nanostructuring, in particular nanothick oxide films supported on metals, and 2) doping of oxides with substitutional metal ions. After addressing methodological aspects related to the theoretical simulations of these materials, we have considered the role of oxide doping in optimizing the structural and electronic properties of supported gold adparticles; we have shown that depending on the dopant and the nature of the oxide it is possible to finely tune the shape and the charge state of adsorbed metal particle. Moreover we have combined oxide doping and nanostructuring in modifying the work function of metal substrates. By varying parameters like nature, position, and concentration of dopants within the metal-supported oxide films, it is possible in principle to modify the work function of the metallic support in a desired way.
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Dessal, Caroline. « Influence de l'atmosphère réactive sur la stabilité structurale de catalyseurs Pt1 supporté et performances associées en oxydation de CO et photogénération d'hydrogène ». Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1305/document.

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Ce travail de thèse a consisté en l’étude de catalyseurs ultradispersés, composés de clusters nanométriques ou d’atomes isolés (single-atom catalysts, SACs) de métal, une nouvelle classe de catalyseurs faisant actuellement l’objet d’un engouement mondial. Les systèmes Pt/?-Al2O3 et Pt/TiO2 ont été préparés, caractérisés et testés en oxydation de CO et photogénération d’hydrogène, respectivement. Plusieurs méthodes d’imprégnation et de traitement thermique ont été comparées, notamment grâce à l’analyse de la dispersion du platine par microscopie électronique en transmission à balayage (STEM). Pour la préparation de SACs, notre choix s’est finalement porté sur l’imprégnation à humidité naissante d’une faible charge de précurseur Pt(NH3)4(NO3)2, suivie d’une calcination à l’air. L’étude des performances catalytiques et de l’évolution structurale des catalyseurs au cours des réactions a permis de montrer que les atomes isolés (cations) de platine étaient moins actifs que les clusters (réduits) pour les deux systèmes catalytiques étudiés. Dans le cas de Pt/?-Al2O3, des suivis par spectroscopie d’absorption X (XAS) operando en rayonnement synchrotron, spectroscopie infrarouge par réflexion diffuse (DRIFTS) operando et microscopie environnementale (E-STEM) ont montré la formation et la déstabilisation des SACs, cette dernière étant toutefois moindre en conditions oxydantes. En effet, l’oxygène stabilise le platine isolé via la formation de plusieurs liaisons Pt-O-Al comme montré par modélisation DFT, alors que la présence d’un composé réducteur (CO, H2) conduit à la formation de clusters, mobiles sur leur support. Ce travail met en évidence les limites possibles concernant la stabilisation et la mise en œuvre des SACs dans des réactions catalytiques impliquant des conditions réductrices
This PhD work is focused on the study of ultradispersed catalysts, composed of nanometer-sized clusters or isolated atoms (single-atom catalysts, SACs) of metal, a new class of catalysts which are currently the object of worldwide interest. The Pt/?-Al2O3 and Pt/TiO2 systems were prepared, characterized and evaluated for CO oxidation and hydrogen photogeneration, respectively.Several methods of impregnation and thermal treatment were compared, in particular through platinum dispersion analysis using scanning electron microscopy (STEM). For the preparation of SACs, our choice finally turned to the incipient wetness impregnation of Pt(NH3)4(NO3)2 precursor at low loading, followed by calcination in air.For the two catalytic systems of interest, the study of the performances and the structural evolution of the catalysts during the reactions shows that isolated Pt atoms (cations) are less active than their (reduced) cluster counterparts.In the case of Pt/?-Al2O3, operando X-ray absorption spectroscopy (XAS) using synchrotron radiation, operando diffuse reflectance infrared spectroscopy (DRIFTS), and environmental microscopy (E-STEM) allowed us to monitor the SAC formation and destabilization, the latter being however limited in oxidizing conditions. Indeed, the presence of oxygen stabilizes single Pt atoms via the formation of several Pt-O-Al bonds as shown by DFT modeling, whereas the presence of a reducing compound (CO, H2) leads to the formation of Pt clusters, mobile on their support.This work highlights the possible limitations in the stabilization and implementation of SACs for catalytic reactions involving reducing conditions
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Gotterbarm, Karin [Verfasser], et Hans-Peter [Akademischer Betreuer] Steinrück. « Model Catalysis – Single Crystal Surfaces and Graphene-Supported Metal Nanocluster Arrays Studied by In Situ High Resolution XPS / Karin Gotterbarm. Gutachter : Hans-Peter Steinrück ». Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2015. http://d-nb.info/1076166555/34.

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Chou, Chung-Pin, et 周崇斌. « Supported Cobalt Nanoclusters on an Insulating Si3N4 Film ». Thesis, 2002. http://ndltd.ncl.edu.tw/handle/54312046120257857482.

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碩士
國立清華大學
物理學系
90
In this study, a novel phenomenon of forming monodispersed Co nanoparticles at room temperature on a single-crystal Si3N4 dielectric thin film is presented. Results of very narrow size distributions with an average size of ~30 Co atoms have been obtained. We have found that cobalt clusters deposited on Si3N4 are stable with respect to cluster agglomeration/coalescence and thermal decomposition. Also, we have confirmed that the average size of Co clusters is independent of the deposition time and insensitive to the magnitude of the deposition flux. Therefore, their areal density can be controlled by the deposition time. The motivation for using a single-crystal Si3N4 support is two-fold. First, the dielectric support reduces chemical intermixing and electronic coupling (Si3N4 is an excellent diffusion barrier with a bandgap energy of 4-5 eV) between metal clusters and the substrate compared with situations using semiconductor or metal surfaces. Second, the defect-free Si3N4 surface provides us a unique opportunity to study the formation of metal clusters without the influence of surface defects. Consequently, quantum effect can play an important role in the size control.
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Shiu, Hung-wei, et 許紘瑋. « Catalytic properties of Au nanoclusters supported on Al2O3/NiAl (100) surface ». Thesis, 2006. http://ndltd.ncl.edu.tw/handle/82083431818454577809.

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碩士
國立中央大學
物理研究所
95
We have studied the adsorption and decomposition of methanol on well-defined supported Au nanoclusters as a model catalyst by using synchrotron-based high-resolution photoemission spectroscopy (PES). Au nanoclusters are deposited on well-ordered Al2O3 film grown on NiAl (100) through vapor deposition in the ultrahigh vacuum conditions (＜3 x 10-10 torr) at 300 K, 450 K, and 570 K. Gold nanoclusters are studied by using both PES and scanning tunneling microscopy (STM). Form STM images, Au atoms nucleated on crystalline Al2O3 films as nanoclusters and the average size of Au nanoclusters is slightly increased at the deposition temperature of 450 K. However, at 570 K deposition temperature sudden change in the average size of Au nanoclusters is observed, which is probably due to higher diffusion coefficient. To study methanol decomposition, methanol was adsorbed on Au/Al2O3/NiAl (100) at 120 K and subsequently annealed to different temperatures. In our annealing experiment we observe that the methanol C1s peak shifts toward lower binding energy with annealing temperature, which indicates more than one intermediate C-species before it decomposes to CO. We also found the activity for methanol decomposition is highly dependent on the structure of supported Au catalyst. After annealing to 310 K, a sudden shift for C1s peaks may imply that C-O scission and reforming to another hydrocarbon species.
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Livres sur le sujet "Supported nanoclusters"

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Burkardt, Sven. Oxide- And Oxide-Supported Nanoclusters on Quasicrystals. Logos Verlag Berlin, 2009.

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Vang, R. T., S. Wendt et F. Besenbacher. Nanocatalysis. Sous la direction de A. V. Narlikar et Y. Y. Fu. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780199533060.013.12.

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This article discusses nanocatalysis and especially the interrelation between the structure, composition and properties of catalysts. It begins with a review of techniques that have been developed and employed for surface characterization, which can be divided intothree main areas: spectroscopy, diffraction, and microscopy. After describing the nanocharacterization tools, the article considers the theoretical underpinnings of catalysts and catalytic processes. It also examines how detailed atomic-scale insight into elementary surface processes relevant to catalysis can be obtained mainly by means of high-resolution scanning tunnelling microscope studies on single-crystal surfaces. More specifically, it explores the surface structure, adsorption, dissociation and diffusion, and surface chemical reactions of catalysts. The article also looks at the design of new catalysts from first principles and concludes with an assessment of nanocatalysts and transmission electron microscope studies of nanoclusters on high surface area supports.
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Chapitres de livres sur le sujet "Supported nanoclusters"

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Kim, Byung Joo, Young Seak Lee et Soo Jin Park. « A Gas Control by Metal Nanoclusters-Supported Porous Carbon Nanofibers ». Dans Solid State Phenomena, 5–8. Stafa : Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/3-908451-27-2.5.

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Fortunelli, Alessandro, et Giovanni Barcaro. « Density-Functional Theory of Free and Supported Metal Nanoclusters and Nanoalloys ». Dans Metal Clusters and Nanoalloys, 29–79. New York, NY : Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4614-3643-0_2.

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Tiwari, Aarti, et Tharamani C. Nagaiah. « Electrocatalytic Borohydride Oxidation by Supported Tungsten Oxide Nanoclusters Towards Direct Borohydride Fuel Cells ». Dans Materials, Energy and Environment Engineering, 205–10. Singapore : Springer Singapore, 2017. http://dx.doi.org/10.1007/978-981-10-2675-1_24.

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Naumkin, Fedor Y. « Chapter 2. Rational Design of Mixed Nanoclusters : Metal Shells Supported and Shaped by Molecular Cores ». Dans Theoretical and Computational Chemistry Series, 26–57. Cambridge : Royal Society of Chemistry, 2011. http://dx.doi.org/10.1039/9781849732680-00026.

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Kim, Seok, Mi Hwa Cho, Soo Han Kwon et Soo Jin Park. « Electrochemical Characteristics of Platinum Nanocluster Catalysts Using Oxyfluorinated Carbon Nanotubes Supports ». Dans Solid State Phenomena, 155–58. Stafa : Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/3-908451-27-2.155.

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Wayne Goodman, D. « Catalysis by Supported Gold Nanoclusters ». Dans Dekker Encyclopedia of Nanoscience and Nanotechnology, Second Edition - Six Volume Set (Print Version). CRC Press, 2004. http://dx.doi.org/10.1201/9781439834398.ch36.

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Wayne Goodman, D. « Catalysis by Supported Gold Nanoclusters ». Dans Dekker Encyclopedia of Nanoscience and Nanotechnology, Second Edition - Six Volume Set (Print Version), 744–52. CRC Press, 2008. http://dx.doi.org/10.1201/noe0849396397.ch66.

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Veith, Gabriel M., Andrew R. Lupini et Nancy J. Dudney. « Magnetron Sputtering to Prepare Supported Metal Catalysts ». Dans Metal Nanoclusters in Catalysis and Materials Science, 347–53. Elsevier, 2008. http://dx.doi.org/10.1016/b978-044453057-8.50023-4.

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Fortunelli, Alessandro, et Riccardo Ferrando. « Theoretical Modelling of Oxide-Supported Metal Nanoclusters and Nanoalloys ». Dans Metal Nanoparticles and Nanoalloys, 159–211. Elsevier, 2012. http://dx.doi.org/10.1016/b978-0-08-096357-0.00003-0.

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Marco, Zecca, Centomo Paolo et Corain Benedetto. « Metal Nanoclusters Supported on Cross-Linked Functional Polymers : A Class of Emerging Metal Catalysts ». Dans Metal Nanoclusters in Catalysis and Materials Science, 201–32. Elsevier, 2008. http://dx.doi.org/10.1016/b978-044453057-8.50012-x.

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Actes de conférences sur le sujet "Supported nanoclusters"

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Kudryashov, S. I., S. G. Ionov et N. B. Zorov. « Production of Supported Carbon Nanoclusters at Laser Ablation of Foam Graphite ». Dans The European Conference on Lasers and Electro-Optics. Washington, D.C. : Optica Publishing Group, 1998. http://dx.doi.org/10.1364/cleo_europe.1998.cthh86.

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Foam graphite is a new and perspective material for laser ablation applications possessing of very low (subcriticai) bulk density and high concentration of nonequilibrium chemically-induced structural defects (vacancies and etc.). It shows “black body” absorbance, very low transversal thermal diffusivity and sound velocity due to its “sandwich-like” structure of graphite crystallites. Equilibrium laser evaporation of the low-density foam graphite occurs in regular air gaps of its “sandwich-like” structure and thus critical state of carbon seems to be produced. The droplet-like structure of critical state has been predicted by theory of condensed matter state earlier. Therefore laser-induced carbon critical state seems to be intensive source of carbon nanoclusters.
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Nolan, Michael. « Supported metal and metal oxide nanoclusters : insights from first principles simulations (Conference Presentation) ». Dans Low-Dimensional Materials and Devices 2019, sous la direction de Nobuhiko P. Kobayashi, A. Alec Talin et Albert V. Davydov. SPIE, 2019. http://dx.doi.org/10.1117/12.2530619.

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Faruque, Md Omar, Dongke Li, Jinglin Li, Baowen Zhou et Sharif Md Sadaf. « InGaN nanostructures supported rhodium nanoclusters for green syngas production from CO2 and H2O powered by sunlight ». Dans 2022 Photonics North (PN). IEEE, 2022. http://dx.doi.org/10.1109/pn56061.2022.9908366.

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Rapports d'organisations sur le sujet "Supported nanoclusters"

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D. W. Goodman, J. Wang, B. K. Min, E. Ozensoy et F. Yang. Toward an Understanding of Catalysis by Supported Metal Nanoclusters. Office of Scientific and Technical Information (OSTI), janvier 2002. http://dx.doi.org/10.2172/813462.

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Judith C. Yang et Duane Johnson, Anatoly Frenkel Ralph G. Nuzzo. The Reactivity and Structural Dynamics of Supported Metal Nanoclusters Using Electron Microscopy, in situ X-Ray Spectroscopy, Electronic Structure Theories, and Molecular Dynamics Simulations. Office of Scientific and Technical Information (OSTI), juillet 2008. http://dx.doi.org/10.2172/933137.

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