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Author: Kostya S Novoselov
Publisher: World Scientific
ISBN: 9811247862
Category : Science
Languages : en
Pages : 448
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Book Description
This book is for senior undergraduates, graduate students and researchers interested in understanding the physical and chemical interactions of organic semiconductors on emergent two-dimensional (2D) materials. Molecular electronics has come of age, and there is now a pressing need to understand molecule-2D material heterointerfaces at the nanoscale. The purpose of this book is to present a coherent coverage of these heterointerfaces for next generation molecular memories, switches, bio-sensors and magnetic quantum devices. In this interdisciplinary collection, advances in the application of scanning probe and high-resolution synchrotron techniques are illustrated.
Author: Kostya S Novoselov
Publisher: World Scientific
ISBN: 9811247862
Category : Science
Languages : en
Pages : 448
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Book Description
This book is for senior undergraduates, graduate students and researchers interested in understanding the physical and chemical interactions of organic semiconductors on emergent two-dimensional (2D) materials. Molecular electronics has come of age, and there is now a pressing need to understand molecule-2D material heterointerfaces at the nanoscale. The purpose of this book is to present a coherent coverage of these heterointerfaces for next generation molecular memories, switches, bio-sensors and magnetic quantum devices. In this interdisciplinary collection, advances in the application of scanning probe and high-resolution synchrotron techniques are illustrated.
Author: Eui-Hyeok Yang
Publisher: Elsevier
ISBN: 0128184760
Category : Technology & Engineering
Languages : en
Pages : 502
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Book Description
Synthesis, Modelling and Characterization of 2D Materials and Their Heterostructures provides a detailed discussion on the multiscale computational approach surrounding atomic, molecular and atomic-informed continuum models. In addition to a detailed theoretical description, this book provides example problems, sample code/script, and a discussion on how theoretical analysis provides insight into optimal experimental design. Furthermore, the book addresses the growth mechanism of these 2D materials, the formation of defects, and different lattice mismatch and interlayer interactions. Sections cover direct band gap, Raman scattering, extraordinary strong light matter interaction, layer dependent photoluminescence, and other physical properties. Explains multiscale computational techniques, from atomic to continuum scale, covering different time and length scales Provides fundamental theoretical insights, example problems, sample code and exercise problems Outlines major characterization and synthesis methods for different types of 2D materials
Author: Seung Ryul Na
Publisher:
ISBN:
Category :
Languages : en
Pages : 558
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Book Description
Two-dimensional materials such as self-assembled monolayers (SAMs), graphene, etc. are candidate materials for improving the performance of microelectronics components and MEMS/NEMS devices. In view of their relatively large in-plane dimensions, surface forces are likely to dominate their behavior. The purpose of the current work was to extract not only the adhesion energy (or steady state fracture toughness) but also the traction-separation relation associated with interactions between various two-dimensional materials and substrates. In particular, interactions between SAMs terminated by carboxyl and diamine (COOH/NMe2) groups, hydroxylated silicon surfaces, graphene and silicon, graphene and its seed copper and graphene and epoxy over large areas was considered. Traction-separation relations, which are a continum description of such molecular interactions, were determined by a direct method, which makes use of measurements of crack tip opening displacements; an inverse approach where the key parameters are extracted by comparing measured global parameters with finite element solutions and a hybrid approach in which the direct method was supplemented by finite element analysis. Furthermore, the surface free energy of graphene was measured by contact angle measurements. The most striking observation across all the interactions that were considered is that the interaction ranges were much larger than those attributed to van der Waals forces. While van der Waals models might have been at play between graphene and its seed copper foil and graphene and epoxy, the adhesion energies were surprisingly high. This coupled with the long interaction range suggests that roughness effects modulated the basic force field. Interactions between graphene and silicon and hydroxylated silicon surfaces may have been due to capillary and/or electrostatic again possibly modulated by roughness. The interactions between COOH and NMe2 SAMs became stronger under vacuum, which may have induced chemical bonding, and tougher under mixed-mode loading.
Author: Kuan Qiao (S.M.)
Publisher:
ISBN:
Category :
Languages : en
Pages : 35
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Book Description
Transparency of two-dimensional (2D) materials to inter-molecular interactions has been an unresolved problem. Previous researchers found that water droplets interact with underlying substrates through graphene, as if the graphene is "transparent". However, graphene's transparency determined by droplet wetting angles has been controversial. Recently, precise atomic alignment between epitaxial films and substrates through monolayer graphene has been discovered in a GaAs/graphene/GaAs structure. This finding experimentally confirms the existence of remote atomic interaction through graphene. However, the mechanism of remote interaction through 2D materials at atomic-scale and its relationship with the bonding chemistry of 2D materials have not been fully understood. This thesis reports a systematic understanding of remote atomic interaction through two-dimensional (2D) materials, unveiling the general rules for atomic potential "transparency" that can be universally applied to any 2D material. Our findings indicate that: (1) the degree of ionicity of 3D materials determines the potential field penetration depth, and (2) the iconicity of 2D material interlayer governs the degree of screening of the field from the 3D materials. Thus, pure ionically-bonded materials can substantially transmit their potential through 2D materials. We demonstrate that such ionic bonding potential can penetrate through three layers of graphene as it has no polarity. However, the potential can be screened even by one layer of hexagonal Boron Nitride (hBN) with strong ionic bonding character. This discovery will enable the growth of all types of materials across the periodic table including group I-VII, II-VI, and 111-V as single-crystalline forms on 2D materials followed by exfoliation to form freestanding single-crystalline thin films. These thin films can then be fabricated to produce electronic and photonic devices. At the same time, the cost of the substrates during manufacturing can be dramatically reduced since the substrates can be reused without any post-release treatment after exfoliation.
Author: Chih-Jen Shih (Ph. D.)
Publisher:
ISBN:
Category :
Languages : en
Pages : 302
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Book Description
2D materials are defined as solids with strong in-plane chemical bonds but weak out-of-plane, van der Waals (vdW) interactions. In order to realize potential applications of 2D materials in the areas of optoelectronics, surface modification, and complex materials, there are many engineering challenges associated with understanding and engineering molecular interactions at 2D materials interfaces, which requires understanding and engineering multiscale physical phenomena. With this in mind, the goal of this thesis has been to combine continuum modeling, molecular dynamics (MD) simulations, chemical synthesis, and device fabrication to understand and engineer molecular interactions at 2D materials interfaces at different length scales. The three main topics considered include: (i) wetting behavior of graphene (micrometer scale), (ii) solution processing of graphene and graphene oxide (nanometer scale), and (iii) electronic modification in graphene and molybdenum disulfide (atomic scale). The first part of my thesis investigates the wetting behavior of graphene-coated surfaces. Based on the classical theory of van der Waals interactions, monolayer graphene acts like a "nonlinear translucent" barrier, transmitting about 30% of the original water-substrate interactions through it. The contact angle on a graphene-coated substrate is determined by both liquid-graphene and liquid- substrate interactions. This, in turn, results in different degrees of "wetting transparency". By combining theoretical analysis, MD simulations, and contact angle measurements, I show that monolayer graphene becomes more "transparent" to wetting on hydrophilic substrates and more "opaque" to wetting on hydrophobic substrates. The second part of my thesis develops a fundamental understanding and engineering strategies to disperse graphene and graphene oxide in a liquid phase. The mechanism of stabilization of liquid-phase exfoliated graphene sheets in polar solvents is investigated using potential of mean force (PMF) calculations and MD simulations. Along with a kinetic theory of colloid aggregation, the graphene sheets are predicted to aggregate based on thermodynamic arguments. Because of the different affinities of various solvents for the surface of graphene, efficient solvents can enhance the stability of the graphene sheets by: (i) reducing the depth of the vdW well, and (ii) increasing the energy barrier. Using the calculated PMF curves associated with different solvents, with only one adjustable parameter, the kinetic theory is able to predict the lifetimes of graphene sheets, including ranking the five solvents considered in terms of their ability to stabilize graphene. In addition, I present an advanced concept for the layer-controlled production of pristine large graphene dispersions. The use of ionic graphite intercalation compounds to produce Stage-2 and Stage-3 graphite intercalation compounds (GICs) are shown to be excellent precursors for the production of bilayer and tri-layer graphene dispersions. When combined with an on-chip separation method, a population of large area graphene flakes is produced, such that conventional photolithography is enabled for top-gate device fabrication. My present approach enables the only viable route at this time to produce AB stacked bi- and tri-layer graphene on arbitrary substrates on a large scale. Moreover, a comparative study that combines experiments and MD simulations is carried out to understand the effects of pH on the colloidal stability and surface activity of graphene oxide (GO) aqueous solutions. The reported pH-dependent behavior originates from the degree of deprotonation of the carboxyl groups at the edge of GO sheets. At low pH, the carboxyl groups are protonated, such that the GO sheets become less hydrophilic and form suspended GO aggregates. The GO aggregates formed at lower pH are found to be surface active and do not exhibit the salient critical-micelle-concentration (CMC) feature associated with the formation of surfactant micelles. At higher pH, the carboxyl groups are deprotonated and the strong hydrophilicity of the edge carboxyl groups pulls the GO sheets into bulk water, making GO behave like a regular salt dissolved in water. A series of surface tension measurements further suggests that GO does not behave like a conventional surfactant in both pH 1 and pH 14 aqueous solutions. The third part of my thesis develops engineering strategies to modify electronic characteristics of graphene using molecular adsorption, covalent functionalization, and a molybdenum disulfide (MoS2) - graphene heterojunction. I investigate the effects of surfactant adsorbates on transport characteristics in graphene transistors. The surfactant adsorbates are found to: (i) transfer electrons to graphene, (ii) scatter carrier transport, and (iii) induce more electron-hole puddles on the SiO2 substrate. The mechanism behind the unusually observed behaviors can be rationalized using a new theoretical model based on the self-consistent transport theory. I find that the change in transport characteristics is surfactant-dependent, and results from the interactions between the surfactant adsorbates, graphene, and the underlying SiO2 . In addition, I demonstrate an efficient method to covalently functionalize monolayer and bilayer graphene (MLG and BLG) in a precise and controllable manner using electrochemical aryl diazonium chemistry. Using this method, for the first time, I study the transport characteristics of bottom-gated MLG and dual-gated BLG field effect transistor (FET) devices as a function of the degree of functionalization, which provides insight on the electronic transport in functionalized graphene. I show that the electronic transport in functionalized graphene is limited by the formation of electron-hole puddles and mid-gap states due to chemical functionalization. A more significant transport band gap can be created in functionalized BLG at a highly positive transverse electric displacement field. Moreover, I investigate charge transfer, photoluminescence, and gate-controlled electronic transport in the junction between two 2D materials - MoS2 and graphene. Without applying any transverse electric fields, there is a significant number of electrons transferred from MoS2 to graphene due to their work function difference. The charge transfer also results in the formation of a Schottky barrier at the interface, increasing interlayer impedance between the two materials. Despite the interlayer impedance, the quantum yield for MoS2 in the heterostructure is still considerably quenched, since the hot carriers generated in MoS2 during photoexcitation can overcome the barrier readily, subsequently being collected by the adjacent graphene layer. I fabricate FET devices comprised of the MoS2 - graphene heterostructure, and show that the interlayer impedance can be further manipulated by the gate and drain voltages, demonstrating a new type of FET device, which enables a controllable transition from NMOS digital to bipolar characteristics. I show that an on/off current ratio ~100 can be achieved without sacrificing the field-effect electron mobilities in graphene. This thesis advances our understanding on how to engineer molecular interactions at 2D materials interfaces. Specifically, I demonstrate that by combining continuum theory, MD simulations, chemical synthesis, and device fabrication, one can elucidate the multiscale physics underlying these interactions, and further propose new engineering approaches to overcome the associated challenges. There is ample opportunity and need for the combined theoretical and experimental studies in this emerging field to understand and design these nanoscale materials for various electronic, energy, and environmental applications. As reflected in this thesis, it is hoped that the interactive connections between theories and experiments, as well as the engineering innovations driven by multiscale understanding, will significantly facilitate the development of 2D materials commercialization.
Author: Babak Anasori
Publisher: Springer Nature
ISBN: 3030190269
Category : Technology & Engineering
Languages : en
Pages : 534
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Book Description
This book describes the rapidly expanding field of two-dimensional (2D) transition metal carbides and nitrides (MXenes). It covers fundamental knowledge on synthesis, structure, and properties of these new materials, and a description of their processing, scale-up and emerging applications. The ways in which the quickly expanding family of MXenes can outperform other novel nanomaterials in a variety of applications, spanning from energy storage and conversion to electronics; from water science to transportation; and in defense and medical applications, are discussed in detail.
Author: Gongping Liu
Publisher: John Wiley & Sons
ISBN: 3527348484
Category : Technology & Engineering
Languages : en
Pages : 404
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Book Description
Two-Dimensional-Materials-Based Membranes An authoritative and up to date discussion of two-dimensional materials and membranes In Two-Dimensional-Materials-Based Membranes: Preparation, Characterization, and Applications, a team of distinguished chemical engineers delivers a comprehensive exploration of the latest advances in design principles, synthesis approaches, and applications of two-dimensional (2D) materials—like graphene, metal-organic frameworks (MOFs), 2D layered double hydroxides, and MXene—and highlights the significance and development of these membranes. In the book, the authors discuss the use of membranes to achieve high-efficiency separation and to address the challenges posed in the field. The book also discusses potential challenges and benefits in the future development of advanced 2D nanostructures, as well as their impending implementation in applications in the fields of energy, sustainability, catalysis, electronics, and biotechnology. Readers will also find: A thorough introduction to fabrication methods for 2D-materials-based membranes, including the synthesis of nanosheets, membrane structures, and fabrication methods Descriptions of three types of 2D-materials-based membranes: single-layer membranes, laminar membranes and mixed-matrix membranes Comprehensive discussions of 2D-materials-based membranes for water and ions separation, solvent-water separation and gas separation Explorations of transport mechanism of 2D-materials-based membranes for molecular separations Perfect for membrane scientists, inorganic chemists, and materials scientists, Two-Dimensional-Materials-Based Membranes will also earn a place in the libraries of chemical and process engineers in industrial environments.
Author: Aurelia Meghea
Publisher: BoD – Books on Demand
ISBN: 9535100793
Category : Medical
Languages : en
Pages : 386
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Book Description
In a classical approach materials science is mainly dealing with interatomic interactions within molecules, without paying much interest on weak intermolecular interactions. However, the variety of structures actually is the result of weak ordering because of noncovalent interactions. Indeed, for self-assembly to be possible in soft materials, it is evident that forces between molecules must be much weaker than covalent bonds between the atoms of a molecule. The weak intermolecular interactions responsible for molecular ordering in soft materials include hydrogen bonds, coordination bonds in ligands and complexes, ionic and dipolar interactions, van der Waals forces, and hydrophobic interactions. Recent evolutions in nanosciences and nanotechnologies provide strong arguments to support the opportunity and importance of the topics approached in this book, the fundamental and applicative aspects related to molecular interactions being of large interest in both research and innovative environments. We expect this book to have a strong impact at various education and research training levels, for young and experienced researchers from both academia and industry.
Author: Zongyu Huang
Publisher: CRC Press
ISBN: 1000562840
Category : Science
Languages : en
Pages : 166
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Book Description
Monoelemental 2D materials called Xenes have a graphene-like structure, intra-layer covalent bond, and weak van der Waals forces between layers. Materials composed of different groups of elements have different structures and rich properties, making Xenes materials a potential candidate for the next generation of 2D materials. 2D Monoelemental Materials (Xenes) and Related Technologies: Beyond Graphene describes the structure, properties, and applications of Xenes by classification and section. The first section covers the structure and classification of single-element 2D materials, according to the different main groups of monoelemental materials of different components and includes the properties and applications with detailed description. The second section discusses the structure, properties, and applications of advanced 2D Xenes materials, which are composed of heterogeneous structures, produced by defects, and regulated by the field. Features include: Systematically detailed single element materials according to the main groups of the constituent elements Classification of the most effective and widely studied 2D Xenes materials Expounding upon changes in properties and improvements in applications by different regulation mechanisms Discussion of the significance of 2D single-element materials where structural characteristics are closely combined with different preparation methods and the relevant theoretical properties complement each other with practical applications Aimed at researchers and advanced students in materials science and engineering, this book offers a broad view of current knowledge in the emerging and promising field of 2D monoelemental materials.
Author: Sabu Thomas
Publisher: Elsevier
ISBN: 0323986188
Category : Technology & Engineering
Languages : en
Pages : 540
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Book Description
Sustainable Hydrogels: Synthesis, Properties and Applications highlights the development of sustainable hydrogels from various perspectives and covers a range of topics, including the development and utilization of abundant and/or inexpensive biorenewable monomers to create hydrogels; the mimicry of variable properties inherent to successful commercial hydrogels; and the creation of bio-based hydrogels that are functional equivalents of fossil fuel-derived hydrogels with respect to their properties, yet are capable of benign degradation over much shorter timescales. Some of the challenges facing sustainable polymer chemistry are also discussed. Shifts the focus from theory to practice and demonstrates how the cradle-to-cradle approach support sustainability Includes discussion of life cycle assessments in the production and use of hydrogels Presents various materials for the production of hydrogels
