Academic literature on the topic 'Heterostructures - Metal Nanoparticles'
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Journal articles on the topic "Heterostructures - Metal Nanoparticles"
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Chopra, Nitin, Junchi Wu, and Paaras Agrawal. "Synthesis of Nanoscale Heterostructures Comprised of Metal Nanowires, Carbon Nanotubes, and Metal Nanoparticles: Investigation of Their Structure and Electrochemical Properties." Journal of Nanomaterials 2015 (2015): 1–13. http://dx.doi.org/10.1155/2015/125970.
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One-dimensional nanoscale heterostructures comprised of multisegment gold-nickel nanowires, carbon nanotube, and nickel nanoparticles were fabricated in a unique approach combining top-down and bottom-up assembly methods. Porous alumina template was utilized for sequential electrodeposition of gold and nickel nanowire segments. This was followed by chemical vapor deposition growth of carbon nanotubes on multisegment gold-nickel nanowires, where nickel segment also acted as a carbon nanotube growth catalyst. The aligned arrays of these gold-nickel-carbon nanotube heterostructures were released from porous alumina template and then subjected to wet-chemical process to be decorated with nickel/nickel oxide core/shell nanoparticles. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy were utilized for morphology, interface, defect, and structure characterization. The electrochemical performance of these heterostructures was studied using cyclic voltammetry method and the specific capacitance of various heterostructures was estimated and compared.
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Dorovskikh, Svetlana I., Evgeniia S. Vikulova, David S. Sergeevichev, Tatiana Ya Guselnikova, Ilya V. Korolkov, Anastasiya D. Fedorenko, Dmitriy A. Nasimov, et al. "Heterostructures Based on Noble Metal Films with Ag and Au Nanoparticles: Fabrication, Study of In Vivo Biocompatibility and Antibacterial Activity." Coatings 13, no. 7 (July 19, 2023): 1269. http://dx.doi.org/10.3390/coatings13071269.
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In this work, approaches to the formation of multifunctional film heterostructures based on noble metals for the modification of the surface of implant materials (titanium alloy TiAl6V4 and carbon-fiber-reinforced polyetheretherketone CFR-PEEK) are developed. Such heterostructures consist of continuous layers of platinum (Pt) or iridium (Ir) and antibacterial components on their surface, namely silver (nanoparticles or discontinuous films) and gold (nanoparticles). Chemical or physical gas-phase deposition methods were used for their preparation. The influence of the concentration and form of the antibacterial component on the antibacterial activity and in vivo biocompatibility of the film structures was evaluated for the first time. Differences in the dynamics of silver dissolution depending on Ag concentration in the sample and the type of bottom surface (the noble metal layer = Ir, Pt or TiAl6V4) surfaces allowed us to better understand the nature of the antibacterial action against Staphylococcus aureus and Pseudomonas aeruginosa (S. aureus and P. aeruginosa) of Ag/M heterostructures. From in vivo histological studies using rats, the best biocompatibility was shown by the Ag/M heterostructure with a prolonged release of the low fraction of antibacterial component (Ag).
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Sun, Ying-Hui, Cong-Yan Mu, Wen-Gui Jiang, Liang Zhou, and Rong-Ming Wang. "Interface modulation and physical properties of heterostructure of metal nanoparticles and two-dimensional materials." Acta Physica Sinica 71, no. 6 (2022): 066801. http://dx.doi.org/10.7498/aps.71.20211902.
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<sec>Two-dimensional (2D) material has atomic smooth surface, nano-scale thickness and ultra-high specific surface area, which is an important platform for studying the interface interaction between metal nanoparticles (NPs) and 2D materials, and also for observing the surface atomic migration, structural evolution and aggregation of metal NPs in real time and <i>in situ</i>. By rationally designing and constructing the interfaces of metal NPs and 2D materials, the characterization of the interface structure on an atomic scale is very important in revealing the structure-property relationship. It is expected that the investigation is helpful in understanding the mechanism of interaction between metal and 2D materials and optimizing the performance of the devices based on metal-2D material heterojunctions.</sec><sec>In this review, the recent progress of interface modulation and physical properties of the heterostructure of metal NPs and 2D materials are summarized. The nucleation, growth, structural evolution and characterization of metal NPs on the surface of 2D materials are reviewed. The effects of metal NPs on the crystal structure, electronic state and energy band of 2D materials are analyzed. The possible interfacial strain and interfacial reaction are also included. Because of the modulation of electrical and optical properties of 2D materials, the performance of metal NPs-2D material based field effect transistor devices and optoelectronic devices are improved. This review is helpful in clarifying the physical mechanism of microstructure affecting the properties of metal NPs-2D material heterostructures on an atomic scale, and also in developing the metal-2D material heterostructures and their applications in the fields of electronic devices, photoelectric devices, energy devices, etc.</sec>
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Drozdov, AD, and J. deClaville Christiansen. "Modeling dielectric permittivity of polymer composites filled with transition metal dichalcogenide nanoparticles." Journal of Composite Materials 54, no. 25 (May 1, 2020): 3841–55. http://dx.doi.org/10.1177/0021998320922601.
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A model is developed for the dielectric permittivity of polymer nanocomposites reinforced with transition metal dichalcogenide fillers at microwave frequencies. The model takes into account aggregation of nanoparticles into clusters (that involve both filler and matrix components) and the aspect ratio of aggregates. The governing equations involve four material parameters that are found by matching observations on the real and imaginary parts of the dielectric permittivity of polymers reinforced with MoS2 and WS2 micro- and nanospheres, MoS2 nanosheets and nanoflowers, and composite heterostructures formed by MoS2 and MoS2-CoS2 nanoparticles with graphene and reduced graphene oxide. Good agreement is demonstrated between results of simulation and the experimental data at frequencies in the S, X, and Ku bands of the electromagnetic spectrum. It is shown that composite heterostructures have superior dielectric properties compared with those of neat transition metal dichalcogenide nanoparticles.
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Ignat, Eugenia Corina, Doina Lutic, Gabriel Ababei, and Gabriela Carja. "Novel Heterostructures of Noble Plasmonic Metals/Ga-Substituted Hydrotalcite for Solar Light Driven Photocatalysis toward Water Purification." Catalysts 12, no. 11 (November 2, 2022): 1351. http://dx.doi.org/10.3390/catal12111351.
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Heterostructures formed by close conjunctions of plasmonic metal nanoparticles and non-plasmonic (2D) lamellar nanostructures are receiving extensive interest as solar-light-driven photocatalysts for environmental pollutant remediation. Herein, the conjunction of plasmonic Au or Ag and Ga-substituted hydrotalcite are obtained by exploiting the manifestation of the structural “memory effect” of Ga-substituted hydrotalcite in the aqueous solutions of Au(CH3COO)3 and Ag2SO4, respectively. The 2D layered matrix of MgGaAl plays a dual function; it is involved in the synthesis of the plasmonic metal nanoparticles, and further, is acting as a support. The compressive investigations using X-ray diffraction (XRD), UV-diffuse reflectance spectroscopy (UVDR), infrared spectroscopy (FT-IR), transmission electron microscopy (TEM/HRTEM), high-angle annular dark-field imaging/scanning transmittance electron microscopy (HAADF/STEM) and X-ray photoelectron spectroscopy (XPS) describe structural, composition and nano/micromorphology characteristics of the novel heterostructures, while UVDR analysis afforded to study the features of their plasmonic responses. Results reveal that the catalysts are formed by close conjunction of small nanoparticles of Au or Ag (with a mean size less than 20 nm) that are formed on the larger particles of MgGaAl and own plasmonic features within the visible range. The catalysts performances were tested towards photocatalytic degradation of p-dichlorobenzene and 4-nitrophenol under solar light irradiation. Results revealed that the degradation of the pollutants is entangled to the plasmonic response of the heterostructured catalysts that is the key functionality in promoting photocatalysis and degrading the pollutants, under solar light irradiation. MgGaAl showed a very low photocatalytic activity when irradiated by UV or solar light. Notably, the heterostructured catalysts proceeded in good to excellent yield to remove the tested pollutants, under solar light irradiation. The sustainability of the novel catalysts was assessed through the kinetic analysis of the degradation processes of the tested pollutants and their mixture.
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Qu, Siqi, Jing Guan, Dongqi Cai, Qianshuo Wang, Xiuyun Wang, Wei Song, and Wei Ji. "An Electrochromic Ag-Decorated WO3−x Film with Adjustable Defect States for Electrochemical Surface-Enhanced Raman Spectroscopy." Nanomaterials 12, no. 10 (May 11, 2022): 1637. http://dx.doi.org/10.3390/nano12101637.
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Electrochemical surface-enhanced Raman scattering (EC-SERS) spectroscopy is an ultrasensitive spectro-electrochemistry technique that provides mechanistic and dynamic information on electrochemical interfaces at the molecular level. However, the plasmon-mediated photocatalysis hinders the intrinsic electrochemical behavior of molecules at electrochemical interfaces. This work aimed to develop a facile method for constructing a reliable EC-SERS substrate that can be used to study the molecular dynamics at electrochemical interfaces. Herein, a novel Ag-WO3−x electrochromic heterostructure was synthesized for EC-SERS. Especially, the use of electrochromic WO3−x film suppresses the influence of hot-electrons-induced catalysis while offering a reliable SERS effect. Based on this finding, the real electrochemical behavior of p-aminothiophenol (PATP) on Ag nanoparticles (NPs) surface was revealed for the first time. We are confident that metal-semiconductor electrochromic heterostructures could be developed into reliable substrates for EC-SERS analysis. Furthermore, the results obtained in this work provide new insights not only into the chemical mechanism of SERS, but also into the hot-electron transfer mechanism in metal-semiconductor heterostructures.
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Gilea, Diana, Radu G. Ciocarlan, Elena M. Seftel, Pegie Cool, and Gabriela Carja. "Engineering Heterostructures of Layered Double Hydroxides and Metal Nanoparticles for Plasmon-Enhanced Catalysis." Catalysts 12, no. 10 (October 11, 2022): 1210. http://dx.doi.org/10.3390/catal12101210.
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Artificially designed heterostructures formed by close conjunctions of plasmonic metal nanoparticles (PNPs) and non-plasmonic (2D) lamellar nanostructures are receiving extensive interest. The synergistic interactions of the nanounits induce the manifestation of localized surface plasmon resonance (LSPR) in plasmonic metals in the specific environment of the 2D-light absorbing matrix, impacting their potential in plasmon enhanced catalysis. Specifically, layered double hydroxides (LDH) with the advantages of their unique 2D-layered structure, tuned optical absorption, ease of preparation, composition diversity, and high surface area, have emerged as very promising candidates for obtaining versatile and robust catalysts. In this review, we cover the available PNPs/LDH heterostructures, from the most used noble-metals plasmonic of Au and Ag to the novel non-noble-metals plasmonic of Cu and Ni, mainly focusing on their synthesis strategies toward establishing a synergistic response in the coupled nanounits and relevant applications in plasmonic catalysis. First, the structure–properties relationship in LDH, establishing the desirable features of the 2D-layered matrix facilitating photocatalysis, is shortly described. Then, we address the recent research interests toward fabrication strategies for PNPs/support heterostructures as plasmonic catalysts. Next, we highlight the synthesis strategies for available PNPs/LDH heterostructures, how these are entangled with characteristics that enable the manifestation of the plasmon-induced charge separation effect (PICS), co-catalytic effect, or nanoantenna effect in plasmonic catalysis with applications in energy related and environmental photocatalysis. Finally, some perspectives on the challenges and future directions of PNPs/LDHs heterostructures to improve their performance as plasmonic catalysts are discussed.
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Rehman, Khalil ur, Shaista Airam, Xiangyun Lin, Jian Gao, Qiang Guo, and Zhipan Zhang. "In Situ Formation of Surface-Induced Oxygen Vacancies in Co9S8/CoO/NC as a Bifunctional Electrocatalyst for Improved Oxygen and Hydrogen Evolution Reactions." Nanomaterials 11, no. 9 (August 30, 2021): 2237. http://dx.doi.org/10.3390/nano11092237.
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Creating oxygen vacancies and introducing heterostructures are two widely used strategies in Co-based oxides for their efficient electrocatalytic performance, yet both strategies have rarely been used together to design a bifunctional electrocatalyst for an efficient overall water splitting. Herein, we propose a facile strategy to synthesize oxygen-defect-rich Co9S8/CoO hetero-nanoparticles with a nitrogen-doped carbon shell (ODR-Co9S8/CoO/NC) through the in situ conversion of heterojunction along with surface-induced oxygen vacancies, simply via annealing the precursor Co3S4/Co(OH)2/ZIF-67. The as-prepared ODR-Co9S8/CoO/NC shows excellent bifunctional catalytic activities, featuring a low overpotential of 217 mV at 10 mA cm−2 in the oxygen evolution reaction (OER) and 160 mV at 10 mA cm−2 in the hydrogen evolution reaction (HER). This performance excellency is attributed to unique heterostructure and oxygen defects in Co9S8/CoO nanoparticles, the current work is expected to offer new insights to the design of cost-effective, noble-metal-free electrocatalysts.
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Lord, Robert W., Cameron F. Holder, Julie L. Fenton, and Raymond E. Schaak. "Seeded Growth of Metal Nitrides on Noble-Metal Nanoparticles To Form Complex Nanoscale Heterostructures." Chemistry of Materials 31, no. 12 (May 22, 2019): 4605–13. http://dx.doi.org/10.1021/acs.chemmater.9b01638.
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Sbeta, Mohamed, and Abdullah Yildiz. "Optical response enhancement of GZO/p-Si heterostructures via metal nanoparticles." Materials Research Express 6, no. 8 (May 8, 2019): 085018. http://dx.doi.org/10.1088/2053-1591/ab1c82.
Full textDissertations / Theses on the topic "Heterostructures - Metal Nanoparticles"
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Li, Wen. "Magneto-optical Kerr Effect Spectroscopy Study of Ferromagnetic Metal/Organic Heterostructures." Doctoral thesis, Universitätsbibliothek Chemnitz, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-64103.
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Diese Dissertation stellt die erste Anwendung des magneto-optischen Kerr Effektes (MOKE) auf ferromagnetische Metall/Organische Heterostrukturen zur Aufklärung der optischen und chemischen Eigenschaften dar. Die MOKE-Untersuchungen wurden spektroskopisch in einem Energiebereich von 1.7 eV bis 5.5 eV durchgeführt. Heterostrukturen, wie sie hier untersucht werden, sind relevant für Anwendungen in der organischen Spintronik. Die Auswertung der Experimentellen Daten wird unterstützt durch numerische Simulationen eines Schichtmodells und ergänzende Untersuchung der strukturellen und magnetischen Eigenschaften unter Zuhilfenahme von AFM, TEM, SEM, STXM und SQUID-Magnetometrie.
In der aktuellen Arbeit wurde Ni als Beispiel einer ferromagnetischen Schicht oberhalb oder unterhalb des organischen Films verwendet. Die organische Schicht besteht jeweils aus den diamagnetischen Molekülen Rubren, Pentacen und Fulleren, welche nur ein vernachlässigbares MOKE-Signal aufweisen. Zum Vergleich wurden das metallfreie Phtalocyanin H2Pc, welche ein nur eine bis zwei Größenordnungen schwächeres MOKE Signal als das genutzte Ni zeigen, betrachtet. Selbst Moleküle, welche kein intrinsisches MOKE-Signal zeigen, können über die optische Interferenz Einfluss auf das MOKE Signal von Ni nehmen. Daher kann die Dicke der organischen Schicht genutzt werden, um den Verlauf des MOKE Spektrum zu kontrollieren. Dies wird für Rubren und C60 gezeigt.
Beim Vergleich des MOKE-Spektrums von Rubren/Ni- und Ni/Rubren-Doppelschichten war es möglich zu zeigen, dass die Metallablagerung an der Oberfläche einen Versiegelungseffekt hat, welcher die Oxidation der organischen Unterschicht verlangsamt.
AFM und TEM Messungen zeigen, dass Ni die Morphologie der unteren Rubrenschicht annimmt. Die Proben, die mit einer geringen Wachstumsrate von Rubren hergestellt wurden, weisen bei einer nominellen Schichtdicke von 15 nm klar geformte Rubren-Inseln mit großen Abständen zwischen ihnen auf. In diesen Fällen zeigte die magnetische Hysteresemessung von MOKE bei Raumtemperatur eine unterschiedliche Gestalt in Abhängigkeit von der Photonenenergie. Die Hystereseschleifen wurden durch die Präsenz zweier magnetischer Phasen interpretiert. Die MOKE-Spektren dieser beiden Phasen wurden aus dem experimentellen Spektrum separiert. Die Gestalt des gemessenen Spektrums ändert sich mit der Stärke des angelegten Feldes aufgrund der unterschiedlichen Beiträge der zwei Phasen.
An den ferromagnetischen Metall/organischen Schichten wurde TEM angewendet, um die Größe der Metallpartikel zu bestimmen, sowie STXM um die Orientierung der organischen Moleküle festzustellen. Die Schichtdicke, das Massenverhältnis sowie die Wechselwirkung zwischen Metall und organischen Material beeinflussen nachweislich das MOKE Signal.
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Mouafo, Notemgnou Louis Donald. "Two dimensional materials, nanoparticles and their heterostructures for nanoelectronics and spintronics." Thesis, Strasbourg, 2019. http://www.theses.fr/2019STRAE002/document.
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Cette thèse porte sur l’étude du transport de charge et de spin dans les nanostructures 0D, 2D et les hétérostructures 2D-0D de Van der Waals (h-VdW). Les nanocristaux pérovskite de La0.67Sr0.33MnO3 ont révélé des magnétorésistances (MR) exceptionnelles à basse température résultant de l’aimantation de leur coquille indépendamment du coeur ferromagnétique. Les transistors à effet de champ à base de MoSe2 ont permis d’élucider les mécanismes d’injection de charge à l’interface metal/semiconducteur 2D. Une méthode de fabrication des h-VdW adaptés à l’électronique à un électron est rapportée et basée sur la croissance d’amas d’Al auto-organisés à la surface du graphene et du MoS2. La transparence des matériaux 2D au champ électrique permet de moduler efficacement l’état électrique des amas par la tension de grille arrière donnant lieu aux fonctionnalités de logique à un électron. Les dispositifs à base de graphene présentent des MR attribuées aux effets magnéto-Coulomb anisotropiquesThis thesis investigates the charge and spin transport processes in 0D, 2D nanostructures and 2D-0D Van der Waals heterostructures (VdWh). The La0.67Sr0.33MnO3 perovskite nanocrystals reveal exceptional magnetoresistances (MR) at low temperature driven by their paramagnetic shell magnetization independently of their ferromagnetic core. A detailed study of MoSe2 field effect transistors enables to elucidate a complete map of the charge injection mechanisms at the metal/MoSe2 interface. An alternative approach is reported for fabricating 2D-0D VdWh suitable for single electron electronics involving the growth of self-assembled Al nanoclusters over the graphene and MoS2 surfaces. The transparency the 2D materials to the vertical electric field enables efficient modulation of the electric state of the supported Al clusters resulting to single electron logic functionalities. The devices consisting of graphene exhibit MR attributed to the magneto-Coulomb effect
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Ballentine, Michael Drake. "Imidazolium Ionic Liquids as Multifunctional Solvents, Ligands, and Reducing Agents for Noble Metal Deposition onto Well-Defined Heterostructures and the Effect of Synthetic History on Catalytic Performance." TopSCHOLAR®, 2018. https://digitalcommons.wku.edu/theses/2101.
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1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM]Tf2N) was investigated as a multifunctional solvent, ligand, and reducing agent for platinum deposition onto well-defined CdSe@CdS nanorods. Platinum deposition was carried out thermally and photochemically using Pt(acac)2 as the metal precursor. Thermal deposition was investigated in [BMIM]Tf2N with and without addition of a sacrificial reducing agent, and product topology was compared with the products obtained from polyol reduction using 1,2-hexadecanediol, oleic acid, and oleylamine in diphenyl ether. Photochemically induced platinum deposition was carried out at room temperature in [BMIM]Tf2N, and product topology was compared with the photodeposition products obtained from a toluene dispersion. Thermal deposition of platinum in ionic liquid showed rods of broken morphology and small platinum nanoparticles speckled across the rods’ surface, while photodeposition of platinum exhibited particles decorated throughout the nanorod surface but larger in size than those exhibited by thermal means. Photocatalytic
reduction of methylene blue was studied using these Pt-CdSe@CdS heterostructured nanoparticles, and catalytic performance was correlated with topology and synthetic history. Initial findings of catalytic performance suggest that there in an advantage of depositing platinum nanoparticles onto the CdSe@CdS in the ionic liquid system. Methylene blue dye was degraded using each system and the results show and there is an increased performance of the nanorods synthesized in the ionic system.
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Tinat, Lionel. "Synthèses assistées par micro-ondes et lumière de nanomatériaux pour la catalyse." Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS386.
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Dans ces travaux de thèse, nous avons utilisé des stimuli originaux, les micro-ondes et la lumière, pour l’élaboration d’hétérostructures or/oxyde en solution aqueuse. Dans la première partie de ce travail, nous avons synthétisé des nanoparticules de supports oxydes (CeO2, TiO2 et SnO2) de tailles et de morphologies contrôlées. Des particules isotropes et des nano-bâtonnets de CeO2 ont été obtenues. Des nanoparticules d’anatase et de rutile, avec des morphologies variées, exposant différentes faces cristallines, ont également été synthétisées. Des synthèses simples, dans l’eau, ont permis de préparer des nanoparticules isotropes de SnO2 tandis que l’utilisation d’un milieu acide promeut l’obtention de particules allongées. Pour élucider la différence de mécanismes, une étude in situ combinant la diffusion et la spectroscopie d’absorption X, au sein d’un four à micro-ondes, a permis de dresser un tableau d’ensemble des mécanismes de formation des nanoparticules de SnO2 en solution aqueuse. Un protocole de synthèse en flux continu de SnO2 a également développé permettant la production significative de matériaux. Finalement, en utilisant la diversité des morphologies de TiO2 obtenues, nous avons réalisé la préparation de catalyseurs Au/TiO2 pour l’oxydation de CO par deux méthodes : le dépôt-précipitation à l’urée (DPU) et le photo-dépôt. Le DPU a permis d’obtenir des catalyseurs présentant des performances comparables à leurs homologues préparés sur TiO2 commerciaux et de mettre en évidence un effet potentiel des faces cristallines du support. La méthode par photo-dépôt a également permis de préparer des nanoparticules d’or de tailles comparables à la méthode DPU. Des conclusions préliminaires, sur le mécanisme intervenant lors de ce photo-dépôt, ont finalement été proposéesThe main objective of this study was to carry the one step synthesis of metal/oxide heterostructures combining microwave and UV irradiation. During this work, we prepared nanoparticles of high industrial potential oxides (CeO2, TiO2 and SnO2) with a precise control of the size and morphology. Isotropic particles and nanorods of CeO2 were first synthetized. Then, a large variety of anatase and rutile nanoparticles, with specific crystalline faces were obtained. Syntheses of SnO2 were finally developed, without or with HCl, to obtain isotropic and elongated nanoparticles respectively. To understand the fundamental difference between formation mechanisms of SnO2, we performed an in situ study, in our microwave apparatus, combining small angle X-ray scattering and X-ray absorption spectroscopy. We were able to give new insights on the formation of these nanoparticles in aqueous solutions. We developed then the first microwave assisted continuous flow synthesis of SnO2 to produce significant amount of materials. Finally, we used the synthetized TiO2 nanoparticles as support to prepare gold catalysts with two different methods: the deposition-precipitation with urea (DPU) and the photodeposition. DPU provided as active nanocatalysts as equivalent catalysts prepared with commercial TiO2. We highlighted a potential impact of crystalline faces of the support. Finally, the photodeposition method led to similar supported gold nanoparticles size range as the DPU. We proposed preliminaries conclusions on the mechanism of the photodeposition
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Yang, Po-Yuan, and 楊博淵. "The Study of Metal Nanoparticles :Shape Control and Synthesis of Heterostructures on Photocatalytic Reaction." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/36715520754524467526.
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碩士國立清華大學
化學工程學系
100
We synthesize copper/zinc oxide heterostructures (Cu/ZnO) by thermal decomposition methods and separate the nucleation and growth process by hot injection method, and then obtaining the nanoparticles with the almost same size. We work on the influence of different reaction temperature and the type of injection. By controlling both of the factors, we can synthesize highly crystalline heterostructures with copper nanoparticles of forty nanometers and the zinc oxide shell of the thickness of four nanometers. We transfer Cu/ZnO into water phase, and alloy to the photocatalttic reaction. We are based on the done work of the synthesis of gold/cadmium selenide heterostructures, analyzing further the shell structure. We use cadmium nitrate and sodium borohydride to control the CdSe shell thickness, and analyze the absorption values and measure the photoluminescence signal. In addition we measure two-photon luminescence imaging as well as the photocatalytic reaction. We use TOP and oleylamine to reduce copper chloride at high temperature. By tuning the concentration of copper chloride and the reaction time to prepare copper nanocrystals with morphology evolution.We observe X-ray diffraction patterns to analyze the crystalline structure, and observe absorption values to determine optical properties. Analyzing SEM images and TEM images to Analyze the surface morphology and the rationality of its evolution.
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Li, Wen. "Magneto-optical Kerr Effect Spectroscopy Study of Ferromagnetic Metal/Organic Heterostructures." Doctoral thesis, 2010. https://monarch.qucosa.de/id/qucosa%3A19434.
Full textAbstract:
Diese Dissertation stellt die erste Anwendung des magneto-optischen Kerr Effektes (MOKE) auf ferromagnetische Metall/Organische Heterostrukturen zur Aufklärung der optischen und chemischen Eigenschaften dar. Die MOKE-Untersuchungen wurden spektroskopisch in einem Energiebereich von 1.7 eV bis 5.5 eV durchgeführt. Heterostrukturen, wie sie hier untersucht werden, sind relevant für Anwendungen in der organischen Spintronik. Die Auswertung der Experimentellen Daten wird unterstützt durch numerische Simulationen eines Schichtmodells und ergänzende Untersuchung der strukturellen und magnetischen Eigenschaften unter Zuhilfenahme von AFM, TEM, SEM, STXM und SQUID-Magnetometrie.
In der aktuellen Arbeit wurde Ni als Beispiel einer ferromagnetischen Schicht oberhalb oder unterhalb des organischen Films verwendet. Die organische Schicht besteht jeweils aus den diamagnetischen Molekülen Rubren, Pentacen und Fulleren, welche nur ein vernachlässigbares MOKE-Signal aufweisen. Zum Vergleich wurden das metallfreie Phtalocyanin H2Pc, welche ein nur eine bis zwei Größenordnungen schwächeres MOKE Signal als das genutzte Ni zeigen, betrachtet. Selbst Moleküle, welche kein intrinsisches MOKE-Signal zeigen, können über die optische Interferenz Einfluss auf das MOKE Signal von Ni nehmen. Daher kann die Dicke der organischen Schicht genutzt werden, um den Verlauf des MOKE Spektrum zu kontrollieren. Dies wird für Rubren und C60 gezeigt.
Beim Vergleich des MOKE-Spektrums von Rubren/Ni- und Ni/Rubren-Doppelschichten war es möglich zu zeigen, dass die Metallablagerung an der Oberfläche einen Versiegelungseffekt hat, welcher die Oxidation der organischen Unterschicht verlangsamt.
AFM und TEM Messungen zeigen, dass Ni die Morphologie der unteren Rubrenschicht annimmt. Die Proben, die mit einer geringen Wachstumsrate von Rubren hergestellt wurden, weisen bei einer nominellen Schichtdicke von 15 nm klar geformte Rubren-Inseln mit großen Abständen zwischen ihnen auf. In diesen Fällen zeigte die magnetische Hysteresemessung von MOKE bei Raumtemperatur eine unterschiedliche Gestalt in Abhängigkeit von der Photonenenergie. Die Hystereseschleifen wurden durch die Präsenz zweier magnetischer Phasen interpretiert. Die MOKE-Spektren dieser beiden Phasen wurden aus dem experimentellen Spektrum separiert. Die Gestalt des gemessenen Spektrums ändert sich mit der Stärke des angelegten Feldes aufgrund der unterschiedlichen Beiträge der zwei Phasen.
An den ferromagnetischen Metall/organischen Schichten wurde TEM angewendet, um die Größe der Metallpartikel zu bestimmen, sowie STXM um die Orientierung der organischen Moleküle festzustellen. Die Schichtdicke, das Massenverhältnis sowie die Wechselwirkung zwischen Metall und organischen Material beeinflussen nachweislich das MOKE Signal.
Book chapters on the topic "Heterostructures - Metal Nanoparticles"
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Cozzoli, P. Davide, and Concetta Nobile. "Colloidal oxide-based heterostructured nanocrystals." In Colloidal Metal Oxide Nanoparticles, 401–70. Elsevier, 2020. http://dx.doi.org/10.1016/b978-0-12-813357-6.00016-4.
Full textConference papers on the topic "Heterostructures - Metal Nanoparticles"
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Ezzahri, Y., R. Singh, K. Fukutani, Z. Bian, A. Shakouri, G. Zeng, J. E. Bowers, J. M. Zide, and A. C. Gossard. "Transient Thermal Characterization of ErAs/In0.53Ga0.47As Thermoelectric Module." In ASME 2007 InterPACK Conference collocated with the ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ipack2007-33880.
Full textAbstract:
Embedded metallic nanoparticles in semiconductors have recently been proven to be of great interest for thermoelectric applications. These metallic nanoparticles play the role of scattering centers for phonons and a source of doping for electrons; they reduce simultaneously the thermal conductivity and increase the thermoelectric power factor of the semiconductor. It has also shown that metal/semiconductor heterostructures can be used to break the crystal momentum symmetry for hot electrons in thermionic devices, then increasing the number of electrons participating in transport. A thermoelectric module of 200 N-P pairs of InGaAlAs with embedded ErAs metallic nanoparticles has been fabricated. Network Identification by Deconvolution (NID) technique is then applied for transient thermal characterization of this thermoelectric module. The combination of this new representation of the dynamic behavior of the packaged device with high resolution thin film temperature measurement allows us to obtain information about heat transfer within the thermoelectric module. This is used to extract the thermal resistances and heat capacitances of the module.
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Shakouri, Ali. "Metal/Semiconductor Nanocomposites for Direct Thermal to Electric Energy Conversion." In ASME 2007 2nd Energy Nanotechnology International Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/enic2007-45062.
Full textAbstract:
Thermoelectric effects can be used for direct conversion of heat into electricity using a solid-state device. We describe novel metal/semiconductor nanostructured materials where the heat and charge transport are modified at the atomic level. Hot electron filtering using heterostructure barriers is used to break the trade off between high Seebeck coefficient and high electrical conductivity. Embedded ErAs nanoparticles are used to reduce the lattice thermal conductivity without significant effect on electrical conductivity. The thermal conductivity, electrical conductivity, and Seebeck coefficient of ErAs:InGaAlAs alloys are characterized. The measured ZT is ∼1 at high temperatures 650 K. Integrated circuit fabrication techniques are used to transfer the n- and p-type thin films onto AlN plates and power generation modules are made with hundreds of thin film elements. An output power density >1W/cm2 is demonstrated at an external temperature difference of 120K across the module. Finally, the prospect of other metal semiconductor multilayer structures based on TiN/GaN for high temperature operation will be briefly reviewed.