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Author: Seokjoon Oh Publisher: ISBN: Category : Languages : en Pages : 156
Book Description
This interconversion occurs via complex multistep, multielectron reactions, which can be carried out by either metallic heterogeneous or molecular homogeneous electrocatalysts. Metallic heterogeneous catalysts have a continuum of electronic states that distribute the redox burden of multielectron reactions, allowing for efficient catalysis. However, heterogeneous catalysts display a variety of active sites and local electronic structures, and are difficult to fine-tune at a molecular level. On the other hand, homogeneous catalysts allow a great degree of synthetic control over the catalytic active site. Moreover, the relative ease in spectroscopic characterization allows a mechanistic understanding of molecular catalysis at a level that is unattainable for heterogeneous catalysis. To bridge the advantages of both types of catalysts, we have developed a surface functionalization strategy for conjugating molecularly well-defined active sites to graphitic carbon surfaces. First, I will discuss the preparation and characterization of two new types of conjugating N-heterocyclic linkages to graphitic carbon surfaces. This work presents a general method for characterizing modified carbon surfaces with molecular-level structural detail. Then, I will present the electrocatalytic carbon dioxide reduction activity of a graphite-conjugated rhenium catalyst, and compare its catalytic behavior to that of a molecular analog. Electrochemical and spectroscopic data show that graphite-conjugated catalysts do not behave identically to their molecular analogs, but rather show properties similar to that of metallic heterogeneous catalysts, providing a unique bridge between the worlds of heterogeneous and homogeneous catalysis. Finally, in the appendix, I will present a chapter on the stability of graphite-conjugated linkages under electrochemical polarization, followed by a chapter on catalyzing the reduction of molecular pyridinium species using a graphite-conjugated rhodium catalyst.
Author: Seokjoon Oh Publisher: ISBN: Category : Languages : en Pages : 156
Book Description
This interconversion occurs via complex multistep, multielectron reactions, which can be carried out by either metallic heterogeneous or molecular homogeneous electrocatalysts. Metallic heterogeneous catalysts have a continuum of electronic states that distribute the redox burden of multielectron reactions, allowing for efficient catalysis. However, heterogeneous catalysts display a variety of active sites and local electronic structures, and are difficult to fine-tune at a molecular level. On the other hand, homogeneous catalysts allow a great degree of synthetic control over the catalytic active site. Moreover, the relative ease in spectroscopic characterization allows a mechanistic understanding of molecular catalysis at a level that is unattainable for heterogeneous catalysis. To bridge the advantages of both types of catalysts, we have developed a surface functionalization strategy for conjugating molecularly well-defined active sites to graphitic carbon surfaces. First, I will discuss the preparation and characterization of two new types of conjugating N-heterocyclic linkages to graphitic carbon surfaces. This work presents a general method for characterizing modified carbon surfaces with molecular-level structural detail. Then, I will present the electrocatalytic carbon dioxide reduction activity of a graphite-conjugated rhenium catalyst, and compare its catalytic behavior to that of a molecular analog. Electrochemical and spectroscopic data show that graphite-conjugated catalysts do not behave identically to their molecular analogs, but rather show properties similar to that of metallic heterogeneous catalysts, providing a unique bridge between the worlds of heterogeneous and homogeneous catalysis. Finally, in the appendix, I will present a chapter on the stability of graphite-conjugated linkages under electrochemical polarization, followed by a chapter on catalyzing the reduction of molecular pyridinium species using a graphite-conjugated rhodium catalyst.
Author: Jeffrey Neal Rosenberg Publisher: ISBN: Category : Languages : en Pages : 31
Book Description
Metal oxo intermediates are evoked and observed in a wide range of natural and man-made catalytic system. These varied systems demonstrate divergent reactivity modes dependent on perturbations to the electronic structure and reaction conditions. It is necessary to uncover electronic structure characterization of reactive metal oxo intermediates to provide an improved means of understanding how perturbations to the electronic structure will direct towards these competing pathways. Herein, we have developed a platform for the study of site isolated metal oxo intermediates with a unique electronic structure derived from a conjugated linkage between graphitic carbon edge sites and a chelated metal center. This linkage results in a high degree of electronic coupling between the isolated metal site and the band structure of the graphitic carbon material, referred to as graphite-conjugated catalysts (GCCs). Specifically, we have synthesized a pyrazine-linked conjugated salen-type ligand platform which has been metallated with Mn2+ and used to functionalize graphitic carbon electrodes and powder. XPS surface characterization on the N and Mn chemical environments and relative abundance indicate the desired surface condensation to form a pyrazinic linkage has proceeded as desired. Electrochemical characterization of functionalized electrodes by cyclic voltammogram show three distinct features. Two reversible redox features consistent with proton-coupled electron transfers at the pyrizinic linkages and a third feature, putatively assigned to the metal site. Future work on this project will involve 1) the expansion of the scope of metallation to additional first row transition metals, 2) thermal reactivity studies, 3) in-situ XAS studies, and 4) electrochemical oxygen-reduction reactivity studies.
Author: Hubert Jaeger Publisher: John Wiley & Sons ISBN: 3527674039 Category : Technology & Engineering Languages : de Pages : 1008
Book Description
An excellent overview of industrial carbon and graphite materials, especially their manufacture, use and applications in industry. Following a short introduction, the main part of this reference deals with industrial forms, their raw materials, properties and manifold applications. Featuring chapters on carbon and graphite materials in energy application, and as catalysts. It covers all important classes of carbon and graphite, from polygranular materials to fullerenes, and from activated carbon to carbon blacks and nanoforms of carbon. Indispensable for chemists and engineers working in such fields as steel, aluminum, electrochemistry, nanotechnology, catalyst, carbon fibres and lightweight composites.
Author: Philippe Serp Publisher: John Wiley & Sons ISBN: 0470403691 Category : Science Languages : en Pages : 603
Book Description
This is the first comprehensive book covering all aspects of the use of carbonaceous materials in heterogeneous catalysis. It covers the preparation and characterization of carbon supports and carbon-supported catalysts; carbon surface chemistry in catalysis; the description of catalytic, photo-catalytic, or electro-catalytic reactions, including the development of new carbon materials such as carbon xerogels, aerogels, or carbon nanotubes; and new carbon-based materials in catalytic or adsorption processes. This is a premier reference for carbon, inorganic, and physical chemists, materials scientists and engineers, chemical engineers, and others.
Author: Liming Dai Publisher: John Wiley & Sons ISBN: 3527811427 Category : Technology & Engineering Languages : en Pages : 746
Book Description
Offering comprehensive coverage of this hot topic, this two-volume handbook and ready reference treats a wide range of important aspects, from synthesis and catalytic properties of carbon materials to their applications as metal-free catalysts in various important reactions and industrial processes. Following a look at recent advances in the development of carbon materials as carbon-based metal-free catalysts, subsequent sections deal with a mechanistic understanding for the molecular design of efficient carbon-based metal-free catalysts, with a special emphasis on heteroatom-doped carbon nanotubes, graphene, and graphite. Examples of important catalytic processes covered include clean energy conversion and storage, environmental protection, and synthetic chemistry. With contributions from world-leading scientists, this is an indispensable source of information for academic and industrial researchers in catalysis, green chemistry, electrochemistry, materials science, nanotechnology, energy technology, and chemical engineering, as well as graduates and scientists entering the field.
Author: Liming Dai Publisher: John Wiley & Sons ISBN: 3527811435 Category : Technology & Engineering Languages : en Pages : 746
Book Description
Offering comprehensive coverage of this hot topic, this two-volume handbook and ready reference treats a wide range of important aspects, from synthesis and catalytic properties of carbon materials to their applications as metal-free catalysts in various important reactions and industrial processes. Following a look at recent advances in the development of carbon materials as carbon-based metal-free catalysts, subsequent sections deal with a mechanistic understanding for the molecular design of efficient carbon-based metal-free catalysts, with a special emphasis on heteroatom-doped carbon nanotubes, graphene, and graphite. Examples of important catalytic processes covered include clean energy conversion and storage, environmental protection, and synthetic chemistry. With contributions from world-leading scientists, this is an indispensable source of information for academic and industrial researchers in catalysis, green chemistry, electrochemistry, materials science, nanotechnology, energy technology, and chemical engineering, as well as graduates and scientists entering the field.
Author: Alexander Dean Todd Publisher: ISBN: Category : Languages : en Pages : 292
Book Description
While much of the recent work regarding carbon materials has centered on monolayer graphene, we have focused on the relatively inexpensive, and readily accessible graphite oxide (GO) and thermally-reduced graphite oxide (TRG) to develop new catalysts and polymer composites. Indeed, the reactivity and physical properties inherent to GO has led to improved GO-based catalysis and composite materials with more robust mechanical properties. GO in combination with zeolite NaY dehydrated a variety of alcohols to their corresponding olefinic products under mild conditions. Although GO at 15 wt% loading was an active dehydration catalyst, it was found that the GO loading could be reduced by 50% when used cooperatively with NaY (7.5 wt%). Ultimately, it was determined that the acidity of GO was able to convert the NaY into an acidic form without the added step of ammonium exchange or high-temperature calcination. For the former application, polyethylene/thermally reduced graphite oxide (TRG) composites have been synthesized under mild conditions (1 atm ethylene and 40 °C) using (n-BuCp)2ZrCl2 activated with methylaluminoxane (MAO) as the polymerization catalyst. Although the thermal properties of the aforementioned composites were relatively unchanged when compared to polyethylene, significant enhancements in the mechanical properties were observed (e.g., up to 57% increase in the tensile strength and 170% increase the Young’s modulus for composites containing 5.2 wt% TRG). Donor-acceptor conjugated polymers, where the backbone consists of an alternating electron rich and electron poor [pi]-conjugated repeat unit, have some of the highest reported power conversion efficiencies to date. Conventional synthetic methods for synthesizing donor-acceptor conjugated polymers have relied upon Pd-catalyzed Stille- or Suzuki-type polycondensations and typically afford ill-defined polymers with variable molecular weights and broad polydispersities (Đs). We were interested in synthesizing well-defined donor-acceptor conjugated polymers and have developed a method to polymerize a donor-acceptor monomer based on thiophene and 5,6-difluorobenzotriazole in a controlled fashion using Ni-catalyzed Kumada catalyst-transfer polycondensation (KCTP). By altering the initial catalyst-to-monomer ratio, the M [subscript n] of the resulting polymers (PFBTzHT) ranged from 6.2 kDa – 22.9 kDa, while maintaining narrow Đs (≤ 1.4). Moreover, under the optimized polymerization conditions, the M [subscript n] was found to increase linearly with monomer conversion. Ultimately, the quasi-living nature of the polymerization allowed for the synthesis of well-defined diblock copolymers of PFBTzHT and poly(3-hexylthiophene) (PFTBTz-b-P3HT).
Author: Jean-Michel Savéant Publisher: John Wiley & Sons ISBN: 047175806X Category : Science Languages : en Pages : 505
Book Description
This book is based on the George Fisher Baker Lecture given by Jean-Michel Savéant at Cornell University in Fall 2002. * The first book focusing on molecular electrochemistry * Relates to other fields, including photochemistry and biochemistry * Outlines clearly the connection between concepts, experimental illustrations, proofs and supporting methods * Appendixes to provide rigorous demonstrations to prevent an overload of algebra in the main text * Applications-oriented, focused on analyzing the results obtained rather than the methodology
Author: Yuliang Li Publisher: John Wiley & Sons ISBN: 3527347879 Category : Technology & Engineering Languages : en Pages : 404
Book Description
Graphdiyne Discover the most cutting-edge developments in the study of graphdiyne from a pioneer of the field In Graphdiyne: Fundamentals and Applications in Renewable Energy and Electronics, accomplished chemist Dr. Yuliang Li delivers a practical and insightful compilation of theoretical and experimental developments in the study of graphdiyne. Of interest to both academics and industrial researchers in the fields of nanoscience, organic chemistry, carbon science, and renewable energies, the book systematically summarizes recent research into the exciting new material. Discover information about the properties of graphdiyne through theoretical simulations and experimental characterizations, as well as the development of graphdiyne with appropriate preparation technology. Learn to create new graphdiyne-based materials and better understand its intrinsic properties. Find out about synthetic methodologies, the controlled growth of aggregated state structures, and structural characterization. In addition to demonstrating the interdisciplinary potential and relevance of graphdiyne, the book also offers readers: A thorough introduction to basic structure and band gap engineering, including molecular and electronic structure, mechanical properties, and the layers structure of bulk graphdiyne Explorations of Graphdiyne synthesis and characterization, including films, nanotube arrays and nanowires, nanowalls, and nanosheets, as well as characterization methods Discussions of the functionalization of graphdiyne, including heteroatom doping, metal decoration, and absorption of guest molecules Rigorous treatments of Graphdiyne-based materials in catalytic applications, including photo- and electrocatalysts Perfect for organic chemists, electronics engineers, materials scientists, and physicists, Graphdiyne: Fundamentals and Applications in Renewable Energy and Electronics will also find its place on the bookshelves of surface and solid-state chemists, electrochemists, and catalytic chemists seeking a one-stop reference on this rising-star carbon material.
Author: Seokjoon Oh
Author: Seokjoon Oh
Author: Jeffrey Neal Rosenberg
Author: Hubert Jaeger
Author: Texas A & M University. Department of Chemistry
Author: Philippe Serp
Author: Liming Dai
Author: Liming Dai
Author: Alexander Dean Todd
Author: Jean-Michel Savéant
Author: Yuliang Li