Download or read book Mechanistic Studies of Water Oxidation and Carbon Dioxide Reduction Using Transition Metal Catalysts with Protic Ligands written by Dalton Bodine Burks and published by . This book was released on 2019 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt: The majority of energy produced in the world is derived from fossil fuels which are finite and have deleterious environmental effects. For a sustainable and environmentally-friendly energy future, alternative, renewable energy sources are desired. Two reactions that could have applications towards developing renewable energy sources are water oxidation to produce hydrogen and carbon dioxide reduction to form various products (e.g. formic acid or carbon monoxide); however, these reactions require catalysts to efficiently produce the desired products. Efforts to synthesize, characterize, and study catalysts for these reactions are discussed in this dissertation. The first chapter serves as an introduction to energy-related catalytic reactions. In Chapter 2, 6,6ʹ-dihydroxybipyridine (6,6ʹ-dhbp)-a protic ligand used with several metals to produce catalysts for energy-related reactions-is studied to determine its thermodynamic acidity. In the following chapter, 6,6ʹ-dhbp is used as a ligand with copper to form complexes that are water oxidation catalysts. Chapters 4 and 5 focus on iridium and ruthenium complexes containing new bidentate ligands composed of pyridinol and N-heterocyclic carbenes (NHCs). These complexes, along with an iridium complex of 6,6ʹ-dhbp, were used as catalysts for the hydrogenation of carbon dioxide to formate and the reverse dehydrogenation of formic acid to carbon dioxide and hydrogen. However, the complexes containing the new bidentate pyridinol-NHC ligands were found to be precatalysts as they undergo transformations and decomposition during the course of the reaction. A nickel-pincer complex with a protic CNC-pincer derived of pyridinol and NHCs was used as a photocatalyst for carbon dioxide reduction in Chapter 6. The protic state of the hydroxy group in the 4-position of the pyridine ring was determined to be important for catalysis, as the deprotonated hydroxy group results in 10 times the catalytic ability as the protonated form. In the penultimate chapter, ruthenium-pincer complexes that are active carbon dioxide photoreduction catalysts are studied mechanistically by UV/vis and IR spectroscopies. The most active catalyst was studied in greater detail with real-time IR spectroscopy to help elucidate potential reaction pathways. The final chapter serves as a conclusion to summarize the results discussed in the dissertation.
Download or read book Understanding Electrocatalytic CO2 Reduction and H2O Oxidation on Transition Metal Catalysts from Density Functional Theory Study written by Zaheer Masood and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A major contribution to global warming is CO2 emitted from the combustion of fossil fuels. Electrochemical processes can help to mitigate the elevated CO2 emissions through either the conversion of CO2 into value-added chemicals or the replacement of fossil fuels with clean fuels such as hydrogen produced from water oxidation. The present dissertation focuses on the mechanistic aspects of electrochemical processes. Electrochemical water oxidation is hindered by the low efficiency of oxygen evolution reaction (OER) at the anode whereas electrochemical reduction of CO2 (ERCO2) is hampered by high overpotentials and poor product selectivity. In this dissertation, we studied the catalytic activity of transition metal-based catalysts, including FeNi spinels, metal-oxide/copper, and d metal cyclam complexes, for both OER and ERCO2 using the density functional theory (DFT) computational approach. We report a combined effort of fabricating FeNi oxide catalysts and identifying the active component of the catalyst for OER. Our collaborators at the University of California, Santa Cruze fabricated a series of FeNi spinels-based materials including Ni(OH)Fe2O4(Cl), Ni(OH)Fe2O4, Fe(OH)Fe2O4(Cl), Fe(OH)Fe2O4, Ni(OH)O(Cl), Ni(OH)O and some show exceptional activity for OER. Combined experimental characterization and computational mechanistic study based on the computational hydrogen electrode (CHE) model revealed that Ni(OH)Fe2O4(Cl) is the active ensemble for exceptional OER performance. We also investigated CO2 reduction to C1 products at the metal-oxide/copper interfaces ((MO)4/Cu(100), M = Fe, Co and Ni) based on the CHE model. The effect of tuning metal-oxide/copper interfaces on product selectivity and limiting potential was clearly demonstrated. This study showed that the catalyst/electrode interface and solvent can be regulated to optimize product selectivity and lower the limiting potential for ERCO2. Applied potential affects the stability of species on the surface of the electrode. The proton-coupled electron transfer (PCET) equilibrium assumed in the CHE model does not capture the change in free energy under the influence of the applied potential. In contrast, the constant electrode potential (CEP) model captures changes in free energy due to applied potential, we applied the CEP model to ERCO2 and OER on (MO)4/Cu(100) and compared the results with those from the CHE model. The results demonstrate that the CHE and the CEP models predict different limiting potentials and product selectivity for ERCO2, but they predict similar limiting potentials for OER. The results demonstrate the importance of accounting for the applied potential effect in the study of more complex multi-step electrochemical processes. We also studied transition metal-based homogeneous catalysts for ERCO2. We examined the performance of transition metal(M)--cyclam(L) complexes as molecular catalysts for the reduction of CO2 to HCOO- and CO, focusing on the effect of changing the metal ions in cyclam on product selectivity (either HCOO- or CO), limiting potential and competitive hydrogen evolution reaction. Our results show that among the complexes, [LNi]2+ and [LPd]2+ can catalyze CO2 reduction to CO, and [LMo]2+ and [LW]3+ can reduce CO2 to HCOO-. Notably, [LMo]2+, [LW]3+, [LW]2+ and [LCo]2+ have a limiting potential less negative than -1.6 V and are based on earth-abundant elements, making them attractive for practical application. In summary, the dissertation demonstrates high-performance catalysts can be designed from earth-abundant transition metals for electrochemical processes that would alleviate the high CO2 level in the environment. On the other hand, completely reversing the increasing trend of CO2 level in the atmosphere requires a collective human effort.
Download or read book Water Oxidation Catalysts written by and published by Academic Press. This book was released on 2019-06-22 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt: Water Oxidation Catalysts, Volume 74, the latest release in the Advances in Inorganic Chemistry series, presents timely and informative summaries on current progress in a variety of subject areas. This acclaimed serial features reviews written by experts in the field, serving as an indispensable reference to advanced researchers. Users will find this to be a comprehensive overview of recent findings and trends from the last decade that covers various kinds of inorganic topics, ranging from theoretical oriented supramolecular chemistry, to the quest for accurate calculations of spin states in transition metals. Provides the authority and expertise of leading contributors from an international board of authors Presents the latest release in the Advances in Inorganic Chemistry series Includes the latest information on water oxidation catalysts
Download or read book Development and Mechanistic Studies of Molecularly Defined Water Oxidation Catalysts written by and published by . This book was released on 2013 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mechanistic Studies of First row Transition Metal Catalyzed Homogeneous CO2 Reduction Via H2 Using Density Functional Theory written by Linbin Yao and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Metal Catalyzed Reactions in Water written by Pierre Dixneuf and published by John Wiley & Sons. This book was released on 2013-01-17 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt: Water is abundant in nature, non-toxic, non-flammable and renewable and could therefore be safer and economical for the chemical industry wherever it is used as a solvent. This book provides a comprehensive overview of developments in the use of water as a solvent for metal catalysis, illustrating the enormous potential of water in developing new catalytic transformations for fi ne chemicals and molecular materials synthesis. A group of international experts cover the most important metalcatalyzed reactions in water and bring together cutting-edge results from recent literature with the first-hand knowledge gained by the chapter authors. This is a must-have book for scientists in academia and industry involved in the fi eld of catalysis, greener organic synthetic methods, water soluble ligands and catalyst design, as well as for teachers and students interested in innovative and sustainable chemistry.
Download or read book Transition Metal Catalysis in Aerobic Alcohol Oxidation written by Francesca Cardona and published by Royal Society of Chemistry. This book was released on 2015 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book deals with the search for environmentally benign procedures for the oxidation of alcohols and gives an overview of their transition-metal-catalyzed aerobic oxidation.
Download or read book Mechanistic Studies of the Water Oxidation Reaction with Molecular Iron Catalysts written by and published by . This book was released on 2020 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mechanistic Studies for Catalytic Transformation of Small Oxygenates on Transition Metals written by Suyash Singh and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past century, heterogeneous catalysis has played a central role in the development of efficient chemical processes for the conversion of fossil resources to fuels and chemicals, and identification of new, sustainable routes to upgrade renewable carbon sources that minimize the ecological footprint. More recently, unprecedented advances in electronic structure theory and related computational methods have provided a major thrust to the efforts that utilize density function theory (DFT) calculations for developing fundamental atomic-level understanding of these processes, and subsequently designing new and improved catalysts. In this dissertation, a combined theoretical and experimental approach is presented to study the reaction mechanisms for the catalytic conversion of formic acid (FA) and propylene oxide on transition metals. An iterative methodology comprising of DFT calculations, reaction kinetics measurements, and mean-field microkinetic modeling is employed to determine the nature of active sites on supported catalysts, explain the experimentally observed trends, and obtain predictions for the surface environment under reaction conditions. A detailed analysis of the DFT derived thermochemistry and kinetics parameters over a wide range of transition metal surfaces is performed to identify the key reactivity descriptors for FA decomposition on transition metal catalysts, and develop semi-empirical linear correlations that are then used to develop a microkinetic modeling based framework for the identification and design of improved (active and selective) bimetallic alloy catalysts. Finally, the possible utilization and applications of these methods and ideas in other key chemical transformations are proposed, and suggestions for future work are included.
Download or read book Elements of Molecular and Biomolecular Electrochemistry written by Jean-Michel Savéant and published by John Wiley & Sons. This book was released on 2006-02-10 with total page 505 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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
Download or read book Fundamental Mechanistic Studies of Formic Acid Decomposition on Transition Metals written by Sha Li and published by . This book was released on 2018 with total page 191 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mechanism Based Design of Green Oxidation Catalysts written by and published by . This book was released on 2015 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: In modern era of scarce resources, developing chemical processes that can eventually generate useful materials and fuels from readily available, simple, cheap, renewable starting materials is of paramount importance. Small molecules, such as dioxygen, dinitrogen, water, or carbon dioxide, can be viewed as ideal sources of oxygen, nitrogen, or carbon atoms in synthetic applications. Living organisms perfected the art of utilizing small molecules in biosynthesis and in generating energy; photosynthesis, which couples carbohydrate synthesis from carbon dioxide with photocatalytic water splitting, is but one impressive example of possible catalytic processes. Small molecule activation in synthetic systems remains challenging, and current efforts are focused on developing catalytic reactions that can convert small molecules into useful building blocks for generating more complicated organic molecules, including fuels. Modeling nature is attractive in many respects, including the possibility to use non-toxic, earth-abundant metals in catalysis. Specific systems investigated in our work include biomimetic catalytic oxidations with dioxygen, hydrogen peroxide, and related oxygen atom donors. More recently, a new direction was been also pursued in the group, fixation of carbon dioxide with transition metal complexes. Mechanistic understanding of biomimetic metal-catalyzed oxidations is critical for the design of functional models of metalloenzymes, and ultimately for the rational synthesis of useful, selective and efficient oxidation catalysts utilizing dioxygen and hydrogen peroxide as terminal oxidants. All iron oxidases and oxygenases (both mononuclear and dinuclear) utilize metal-centered intermediates as reactive species in selective substrate oxidation. In contrast, free radical pathways (Fenton chemistry) are common for traditional inorganic iron compounds, producing hydroxyl radicals as very active, non-selective oxidants. Recent developments, however, changed this situation. Growing families of synthetic iron complexes that resemble active sites of metalloenzymes produce metal-based intermediates (rather than hydroxyl radicals) in reactions with oxygen donors. These complexes are very promising for selective oxygen and peroxide activation. In order to understand the mechanisms of metal-based small molecule activation, kinetically competent metal-oxygen intermediates must be identified. One of the grand challenges identified by the Department of Energy workshop "Catalysis for Energy" is understanding mechanisms and dynamics of catalyzed reactions. The research summarized herein focuses on detailed characterization of the formation and reactivity of various iron-peroxo- and iron-oxo intermediates that are involved in catalysis. Rates of rapid reactions were studied at low temperatures by a specialized technique termed cryogenic stopped-flow spectrophotometry. These measurements identified reaction conditions which favor the formation of catalytically competent oxidants. Chemical structures of reactive complexes was determined, and new, efficient catalysts for hydrocarbon oxidation were synthesized. Importantly, these catalysts are selective, they promote oxidation of hydrocarbons at a specific site. The catalysts are also efficient and robust, hundreds of cycles of substrate oxidation occur within minutes at room temperature. Furthermore, they enable utilization of environmentally friendly oxidants, such as hydrogen peroxide, which produces water as the only byproduct. Mechanistic insights uncovered the role of various acid-containing additives in catalytic oxidations. Proton delivery to the active catalytic sites facilitated oxidations, similarly to the catalytic pathways in metal-containing enzymes. Under certain conditions, two metals in one complex can act in concert, modeling the reactivity of a bacterial enzyme which converts methane into methanol. In related studies, a family of nickel complexes that react with carbon ...
Download or read book Chemical Transformations of Carbon Dioxide written by Xiao-Feng Wu and published by Springer. This book was released on 2018-07-10 with total page 261 pages. Available in PDF, EPUB and Kindle. Book excerpt: The series Topics in Current Chemistry Collections presents critical reviews from the journal Topics in Current Chemistry organized in topical volumes. The scope of coverage is all areas of chemical science including the interfaces with related disciplines such as biology, medicine and materials science. The goal of each thematic volume is to give the non-specialist reader, whether in academia or industry, a comprehensive insight into an area where new research is emerging which is of interest to a larger scientific audience. Each review within the volume critically surveys one aspect of that topic and places it within the context of the volume as a whole. The most significant developments of the last 5 to 10 years are presented using selected examples to illustrate the principles discussed. The coverage is not intended to be an exhaustive summary of the field or include large quantities of data, but should rather be conceptual, concentrating on the methodological thinking that will allow the non-specialist reader to understand the information presented. Contributions also offer an outlook on potential future developments in the field.
Download or read book Testing Novel Water Oxidation Catalysts for Solar Fuels Production written by Carminna Ottone and published by Springer. This book was released on 2019-02-28 with total page 117 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book offers comprehensive information on the main techniques for measuring water-oxidation-catalyst (WOC) performance, with a particular focus on the combined use of sacrificial oxidants and dyes within closed-batch reactors. It provides an overview of the latest advances in the synthesis of more efficient WOCs, followed by an analysis of the requirements for sustainable energy production. Readers will find a detailed description of the reaction mechanism used in catalyst assessment systems, which reveals the benefits and limitations of the most common sacrificial oxidant/dye pair. Experimental techniques including electrochemical methods for characterizing novel and non-photoactive WOCs are also described. Throughout the book, various manganese oxides are used as examples of the techniques reviewed or proposed systems. Cost considerations and technological perspectives of the scale-up of solar-driven hydrogen production are also addressed. Lastly, the book presents lessons learned from the implementation of a large-scale real-world device.
Download or read book Part I Mechanistic Studies of Disodium Tetracarbonylferrate Oxidative additions written by Richard Gerald Finke and published by . This book was released on 1976 with total page 604 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mechanistic and Site Isolation Studies of Transition Metal Oxidation Catalysts written by David Chappel Pribich and published by . This book was released on 1985 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Transition Metal Catalyzed Water Oxidation written by Mauro Schilling and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
