Fantastic Nanoparticles and where to Find Them: Advanced Electron Microscopy for the Investigation of Novel Electrocatalysts PDF Download
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Author: Philipp A. Heizmann
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ISBN:
Category :
Languages : en
Pages : 0
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Author: Philipp A. Heizmann
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Author: Subarna Raj Khanal
Publisher:
ISBN: 9781321194722
Category :
Languages : en
Pages : 139
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Research in noble metal nanoparticles has led to exciting progress in a versatile array of applications. For the purpose of better tailoring of nanoparticles activities and understanding the correlation between their structures and properties, control over the composition, shape, size and architecture of bimetallic and multimetallic nanomaterials plays an important role on revealing their new or enhanced functions for potentials application. Advance electron microscopy techniques were used to provide atomic scale insights into the structure-properties of different materials: PtPd, Au-Au 3 Cu, Cu-Pt, AgPd/Pt and AuCu/Pt nanoparticles. The objective of this work is to understand the physical and chemical properties of nanomaterials and describe synthesis, characterization, surface properties and growth mechanism of various bimetallic and multimetallic nanoparticles. The findings have provided us with novel and significant insights into the physical and chemical properties of noble metal nanoparticles. Different synthesis routes allowed us to synthesize bimetallic: Pt-Pd, Au-Au 3 Cu, Cu-Pt and trimetallic: AgPd/Pt, AuCu/Pt, core-shell and alloyed nanoparticles with monodispersed sizes, controlled shapes and tunable surface properties. For example, we have synthesized the polyhedral PtPd core-shell nanoparticles with octahedral, decahedral, and triangular plates. Decahedral PtPd core-shell structures are novel morphologies for this system. For the first time we fabricated that the Au core and Au 3 Cu alloyed shell nanoparticles passivated with CuS2 surface layers and characterized by Cs-corrected scanning transmission electron microscopy. The analysis of the high-resolution micrographs reveals that these nanoparticles have decahedral structure with shell periodicity, and that each of the particles is composed by Au core and Au 3 Cu ordered superlattice alloyed shell surrounded by CuS 2 surface layer. Additionally, we have described both experimental and theoretical methods of synthesis and growth mechanism of highly monodispersed Cu-Pt nanoclusters. The advance electron microscopy of microanalysis allowed us to study the distribution of Cu and Pt with atomistic resolution. The microanalysis revealed that Pt is embedded randomly in the Cu lattice. A novel grand canonical - Langevin dynamics simulation showed the formation of alloy structures in good agreement with the experimental evidence. Finally, we demonstrated the synthesis of AgPd-Pt trimetallic nanoparticles with two different morphologies: multiply twinned core-shell, and hollow particles. We also investigated the growth mechanism of the nanoparticles using grand canonical-Monte Carlo simulations. We found that the Pt regions grow at overpotentials on the AgPd nanoalloys, forming 3D islands at the early stages of the deposition process and presenting very good agreement between the simulated structures and those observed experimentally. Similarly, we also investigated AuCu/Pt core-shell trimetallic nanoparticles, presenting new way to control the nanoparticles morphologies due to the presence of third metal (Pt). Where, we observed the Pt layers are overgrowth on the as prepared AuCu core by Frank-van der Merwe (FM) and Stranski-Krastanov (SK) growth modes. In addition, these nanostructure presents high index facet surfaces with {211} and (321} families, that are highly open structure surfaces and interesting for the catalytic applications. The results of these studies will be useful for the future applications and the design of advanced functional nanomaterials.
Author: Francisco Solá
Publisher:
ISBN:
Category : Science
Languages : en
Pages :
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In this chapter, the author will review several advanced microscopy techniques developed at the NASA Glenn Research Center in the last 5 years. Topical areas include: unconventional approach to investigate the fine nanoporous structure of aerogels by scanning electron microscopy, new limits for transmission electron microscopy investigation of dispersion and chirality of single-walled carbon nanotubes within a polymer matrix, the importance of microstructure of porous tin dioxide nanostructure that lead to first time detection of methane at room temperature without doping or catalyst, in situ SEM methods to study the thermal stability of nanoparticles on Graphene/Cu based materials, electron beam irradiation effects on carbon nanotube yarns electrical properties, and nanoindentation work of multiphase thermoelectric material.
Author: Paul Joseph Kempen
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Over the past decade, nanotechnology has shown great potential as a platform for cancer diagnosis and treatment. The use of novel imaging techniques including surface enhanced Raman scattering, SERS, to locate nanoparticles inside biological systems shows great promise as a way to detect cancer at an early stage before metastasis has a chance to occur. This dissertation describes the use of electron microscopy to characterize the interactions of SERS based nanoparticles with biological systems. As nanotechnology becomes increasingly employed in biology it is necessary to accurately characterize how these nanoparticles interact with the biological system. Due to the scale of these nanostructures, electron microscopy, with its sub nanometer spatial resolution, is essential to understanding these interactions. In the first section of this work, composite organic inorganic nanoparticles, COINs, composed of silver nanoparticles encapsulated in an organic binder and functionalized with antibodies were analyzed using both scanning and transmission electron microscopy. COINs were functionalized with anti-pEGFR, anti-pstat5 or anti-pstat1 and incubated with EGF stimulated A431 lung cancer cells. TEM analysis revealed that both the anti-pEGFR and anti-pstat5 COINs were internalized by the A431 cells while the anti-pstat1 COINs were not internalized. Anti-pEGFR COINs were located in the cytoplasm of the cell while anti-pstat5 COINs were able to translocate into the nucleus of the cell. In the second section of this work a novel SERS based nanoparticle called a Raman active gold core nanoparticle, R-AuNP, was characterized. The R-AuNP consists of a gold core surrounded by a silica shell. TEM analysis of the nanoparticles revealed that gold core has an average diameter of 65 nm with an overall nanoparticle diameter of 141 nm. In the third section of this work a STEM technique was developed to efficiently locate R-AuNPs in "large" volumes of mouse liver tissue as part of a large scale nanoparticle toxicity study. Mice were injected either intravenously or intrarectally with R-AuNPs and at set time points tissue samples were collected and the liver was analyzed using STEM for both the IV and IR injected mice. This analysis revealed that R-AuNPs were present in every liver sample from the mice injected intravenously with the R-AuNPs. No R-AuNPs were found in the liver samples from mice injected intrarectally with the nanoparticles. This indicates that the R-AuNPs were unable to pass through the colon wall and into the blood stream. With this method over 500,000 μm3 of mouse tissue has been examined to date. In the fourth and final section of this work electron microscopy was utilized to locate R-AuNPs in brain tumors and determine if the nanoparticles spread and accumulated across the entirety of the tumor. A correlative light microscope / scanning electron microscope technique was established utilizing light microscopy to provide information about the overall structure and location of the brain tumor through the use of histological staining protocols and utilizing scanning electron microscopy to accurately locate R-AuNPs within the tissue sample. By mapping the R-AuNP locations onto the light microscopy images it was possible to determine the location of the R-AuNPs with respect to the tumor and show that the R-AuNPs were located at the peripheries of the tumor at multiple locations. This indicates that the R-AuNPs infiltrated and spread across the entirety of the tumor. The utility of the electron microscopy approach is confirmed by these various examples.
Author: Yitian Zeng
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Over the past two decades, nanotechnology has demonstrated great potential in the field of biology and medicine. Nanomaterials, such as gold nanoparticles, with their superior chemical and physical properties, are widely used in a variety of biomedical research, ways ranging from cancer early detection (e.g. liquid biopsy) to treatment (e.g. hyperthermia therapy). On the other hand, advances in nano characterization techniques have enabled new investigations of naturally occurring nanoscale features in the body, in order to understand the pathological processes associated with them. This dissertation describes the use of advanced electron microscopy to characterize nanomaterials of relevance to the field of medicine. Some nanoparticles are lithographically fabricated, some are chemically synthesized, and others are directly extracted from tissues and cells. The morphological, crystallographic, chemical, optical and other physical properties of these nanoparticles are evaluated using a combination of imaging, diffraction and advanced spectroscopy techniques in a transmission electron microscope (TEM) and scanning electron microscope (SEM). In the first part of this work, surface enhanced Raman scattering (SERS) gold nanoparticles were optimized for sensitive detection of tumors by correlating localized surface plasmon resonances (LSPR) with surface enhancement. Electron beam lithography was used to prototype gold nanostructures with a wide variety of shapes, size, interspacing and in different dielectric environments. The LSPR of these structures were measured using electron energy loss spectroscopy (EELS) in a transmission electron microscope operated in scanning mode (STEM) with monochromation. It is found that nanoparticle size and dielectric environment have the most significant effects on localized surface plasmons, which is collective oscillation modes of the free electron gas at the metal surface. By contrast, interspacing has a weaker influence on surface plasmons for the range studied in this dissertation. Larger nanoparticle size and higher dielectric constant result in lower surface plasmon energies. The novelty of this work is that the LSPR from various nanostructure arrays were correlated with their Raman spectra acquired at different illuminating laser energies after incubation with a Raman dye. It is demonstrated that the largest Raman signal intensities are obtained when the illuminating laser energy coincides with, or is slightly higher than, the gold nanoparticle surface plasmon resonance energies (e.g. 90 nm diameter nanodisc particles with a LSPR energy of 1.94 eV show strongest Raman signal enhancement under a 638 nm (1.94 eV) wavelength laser excitation). By comparing various nanostructure shapes with similar surface plasmon energies, it is shown that sharper nanostructures tend to exhibit stronger surface enhancement. This information is useful in designing nanoparticle combinations to generate the largest SERS enhancement for detection of early stage medical problems such as cancer. The second part of this work is focused on naturally occurring particles, in particular, iron deposits in the hippocampal region of a brain to understand the pathological processes related to Alzheimer's diseases (AD). Recent work on iron accumulation in AD brains has led researchers to hypothesize that the oxidation state of iron may be related to neurodegeneration because ferrous iron, compared with ferric iron, may cause oxidative damage and antioxidant depletion on neurons. First, iron rich regions from AD brain tissues were located using correlative magnetic resonance imaging (MRI), optical microscopy (OM), SEM and energy dispersive spectroscopy (EDS). Cross-sections of tissue containing iron deposits were then extracted using focused ion beam (FIB) and subsequently thinned to make them electron transparent. The relative concentrations of ferric and ferrous ions within the iron deposits were determined by studying the intensity ratios of Fe L3:L2 edges from the energy loss near edge structure (ELNES) of the Fe L edge using monochromated STEM-EELS as above. Massive correlation across biological and physical microscopy and spectroscopy techniques was demonstrated for the first time in this work. These observations and insights provide supporting evidence of ferrous iron as being possibly associated with AD. The third and final section addresses characterization of artificial and natural nanoparticle composites. These hybrid nanoparticles, fabricated via a simple extrusion method, can greatly increase the target specificity and cellular uptake in various biomedical applications such as cancer imaging and drug delivery. A negative staining technique was utilized to provide contrast of biological components of these nanoparticles in TEM, and specific proteins of interest were labeled with antibodies conjugated to 100 nm diameter gold iron oxide nanoparticles (GIONs). The combination of superior magnetic, photonic and other physical properties from artificial nanoparticles, along with cellular specificity and biological compatibility from natural nanoparticles makes these hybrid nanoparticles useful for multi-modality imaging and possible medical treatment. Overall, electron microscopy is a versatile and powerful methodology for characterization of a wide variety of nanomaterials. Advanced microscopic and spectroscopic techniques such as monochromatic STEM-EELS and EDS, which are rarely used in the life sciences, have great potential in bringing unique insight into biomedical research.
Author: Thandavarayan Maiyalagan
Publisher: Elsevier
ISBN: 0323857108
Category : Technology & Engineering
Languages : en
Pages : 400
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Nanomaterials for Electrocatalysis provides an overview of the different types of nanomaterials, design principles and synthesis protocols used for electrocatalytic reactions. The book is divided into four parts that thoroughly describe basic principles and fundamental of electrocatalysis, different types of nanomaterials used, and their electrocatalytic applications, limitations and future perspectives. As electrochemical systems containing nanomaterials, with relevance to experimental situation, yield better results, this book highlights new information and findings. Provides an overview of nanomaterials applications for electrocatalytic processes, such as oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER) and CO2 reduction reaction (CO2RR) Provides information on the design and development of various nanomaterials appropriate for electrocatalytic applications Assesses the challenges of manufacturing nanomaterials at an industrial scale for electronic applications
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 35
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Author: Reza Zamani
Publisher:
ISBN:
Category :
Languages : en
Pages : 371
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In this report novel materials for advanced applications are studied by means of the latest microscopy technologies and methodologies which have had a dramatic impact on progress of materials science. The aim was to study phenomena such as polytypism, unusual morphologies, polytypic branching, cation ordering, polarity, epitaxial growth and interface, etc, in order to find adequate explanations for the influence of the phenomena on the properties and applications such as thermoelectricity, p-n junction functionality, photovoltaic efficiency, optoelectronic properties, and sensing response. Various semiconducting materials, i.e. complex chalcogenides, metal oxides, and III-V nanostructures were characterized for this purpose. Here, nanoengineered structures of functional materials at nanoscale are studied by means of advanced electron microscopy methods. Chapter 1 gives a brief introduction to the report; the main purpose of the work, state-of-the-art, challenges and possibilities. In chapter 2 the methodology is described. The results are provided in Chapter 3, 4, and 5, and Chapter 6 is the general conclusions and the outlook. Note that Chapters 3-5 have their own introduction and conclusion. Therefore, chapter 1 consists of a short introduction to the general idea of the study, its importance and the state-of-the-art, and a preface of the thesis. In Chapter 2, after a brief history and the basic concepts of EM, the TEM methodology is described; the advanced TEM techniques used to study the nanostructured semiconductors at atomic scale. In general, it consists of brief descriptions of basic principles of TEM techniques. As experimental results are corroborated by theoretical studies and simulations, these procedures (image processing, simulations, etc) are also described shortly. Chapter 3 is dedicated to nanoengineering crystal structure and morphology of nanocrystals of complex copper-based chalcogenide, from binaries to complex ternaries and quaternaries. In this chapter it is shown that there is a wide range of possibilities for engineering, as many elements can be substituted with the primary cations and anions. Advanced TEM studies are performed in order to figure out the physics behind the property modifications. Phenomena such as morphology change, polytypism, ordering, polarity, electronic band change, strain, etc are elaborately studied, and correlated to the physical properties such as thermoelectricity. CCTSe polypods are the case of a complete structure study to understand the branching mechanism. Therefore, by means of an aberration-corrected TEM the polarity and cation ordering was determined. Polarity-driven morphology and branching mechanism is explained. Moreover, electronic band structure in this polytypic structure is simulated. Chapter 4 is based on the study of nanojunctions in metal oxide heterostructured NWs, structures that can enhance the functionality of the targeted devices, such as photovoltaic cells, or gas sensors. Production of nanojunctions is a successful approach in the context. In this chapter it is shown how coaxial heterostructuring of NWs, e.g. formation of core-shell structures increase the efficiency of the solar cells or enhance the sensitivity/selectivity of the gas sensors. In chapter 5 almost the same approach was followed, nevertheless, this time with III-V NWs. The importance of axial heterostructures and fully-epitaxial and relaxed structure are emphasized. The optoelectronic properties of the GaN NWs, such promising p-n junctions, are examined. Polarity issue, as a remarkably influencing parameter, is precisely studied experimentally. Its effect on electronic band structure in the heterointerface is also proven by the theoretical simulations. In the end, a general conclusion of the whole work and room for further study and future work is discussed in Chapter 6. The ample freedom of structural nanoengineering in the materials, together with development of novel electron microscopy techniques, opens the way towards the new possibilities for the future work.
Author: Chikara Hayashi
Publisher: William Andrew
ISBN:
Category : Technology & Engineering
Languages : en
Pages : 480
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Electron microscopy studies of ultra-fine particles -- Synthesis and characterization of ultra-fine particles -- Ultra-fine particles and microbes -- Application of ultra-fine particles -- Prospects for the future of ultra-fine particles.
Author: Davide Deiana
Publisher:
ISBN:
Category :
Languages : da
Pages :
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