Download or read book The Development and Investigation of Cobalt Catalysts for the Chemical Transformations Related to Artificial Photosynthesis written by Hyun Seo Ahn and published by . This book was released on 2013 with total page 135 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chapter 1. Small domains of cobalt on silica (CoSBA) were prepared by the reaction of Co[N(SiMe3)2]2 and SBA-15, resulting in a range of surface structures as the cobalt loading varied from 0.27 to 5.11 wt%. X-ray absorption spectroscopy (XAS) was employed to characterize these surface structures, which range from single-site cobalt atoms to small clusters of Co3O4. The CoSBA materials exhibit photochemical water oxidation catalysis, revealing distinct catalytic activities associated with characteristic types of surface structures that are dominant in particular concentration regimes. The catalytic turnover frequency for water oxidation of an isolated single-site cobalt atom (0.0143 s−1) is much greater than that observed for a surface atom of a small cluster Co3O4 on silica (0.0006 s−1). The CoSBA catalysts were recyclable for more than seven catalytic cycles (> 200 turnovers) with additional sacrificial oxidant, and no leaching of cobalt was observed. Post-catalytic analysis of CoSBA by XAS revealed that the cobalt atoms were partially oxidized to Co3+, without exhibiting significant surface migration and aggregation of cobalt atoms. Chapter 2. Single-site cobalt atoms on various oxide surfaces (TiO2, MgO, SBA-15, AlPO, and Y-Zeolite) were prepared and evaluated as water oxidation catalysts. Superior catalytic rates were observed for cobalt sites on basic supporting oxides (TiO2 and MgO) relative to those on acidic oxides (Y-Zeolite, AlPo, and SiO2). Per-atom turnover frequencies of ca. 0.04 s−1 were achieved, giving initial rates 100 times greater than a surface atom of a Co3O4 nanoparticle. No correlation was observed between catalytic rates and oxygen atom affinities of the supporting oxides. Chapter 3. Cobalt metaphosphate Co(PO3)2 nanoparticles are prepared via the thermolytic molecular precursor (TMP) method. A Ni foam electrode decorated with Co(PO3)2 nanoparticles is evaluated as an anode for water oxidation electrocatalysis in pH 6.4 phosphate-buffered water. Catalytic onset occurs at an overpotential of ca. 310 mV, which is 100 mV lower than that observed for Co3O4 nanoparticles, with a comparable surface area under identical conditions. A per-metal turnover frequency (TOF) of 0.10 - 0.21 s−1 is observed at [eta] = 440 mV, which is comparable to the highest rate reported for a first-row metal heterogeneous catalyst. Post-catalytic characterization of the catalyst resting state by XPS and Raman spectroscopy reveals that surface rearrangement occurs, resulting in an oxide-like surface overlayer. Chapter 4. Linear trimetallic CoIII/CoII/CoIII cobalt complexes with bridging acyl-alkoxy ligands are electrocatalysts for the reduction of tosic acid in acetonitrile. The -OCMe2CH2COMe complex appears to operate homogeneously, and at an onset overpotential of only 25 mV. A turnover frequency of ca. 80 s−1 was observed at an overptotential of 150 mV.

Download or read book From Molecules to Materials written by Elena A. Rozhkova and published by Springer. This book was released on 2015-04-06 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: This interdisciplinary book focuses on the various aspects transformation of the energy from sunlight into the chemical bonds of a fuel, known as the artificial photosynthesis, and addresses the emergent challenges connected with growing societal demands for clean and sustainable energy technologies. The editors assemble the research of world-recognized experts in the field of both molecular and materials artificial systems for energy production. Contributors cover the full scope of research on photosynthesis and related energy processes.

Download or read book Iron and Cobalt Catalysts written by Wilson D. Shafer and published by MDPI. This book was released on 2020-06-23 with total page 414 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the turn of the last century when the field of catalysis was born, iron and cobalt have been key players in numerous catalysis processes. These metals, due to their ability to activate CO and CH, haev a major economic impact worldwide. Several industrial processes and synthetic routes use these metals: biomass-to-liquids (BTL), coal-to-liquids (CTL), natural gas-to-liquids (GTL), water-gas-shift, alcohol synthesis, alcohol steam reforming, polymerization processes, cross-coupling reactions, and photocatalyst activated reactions. A vast number of materials are produced from these processes, including oil, lubricants, waxes, diesel and jet fuels, hydrogen (e.g., fuel cell applications), gasoline, rubbers, plastics, alcohols, pharmaceuticals, agrochemicals, feed-stock chemicals, and other alternative materials. However, given the true complexities of the variables involved in these processes, many key mechanistic issues are still not fully defined or understood. This Special Issue of Catalysis will be a collaborative effort to combine current catalysis research on these metals from experimental and theoretical perspectives on both heterogeneous and homogeneous catalysts. We welcome contributions from the catalysis community on catalyst characterization, kinetics, reaction mechanism, reactor development, theoretical modeling, and surface science.

Download or read book Accelerating the Development of Liquid Fuels Directly from Sunlight written by Xenia Amashukeli and published by . This book was released on 2018 with total page 74 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Development of Cationic Cobalt I complexes for Enantioselective Cycloaddition and Hydrofunctionalization Reactions written by Mahesh M. Parsutkar and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Developments of new catalytic transformations by using earth-abundant metal (base-metal) catalysts have played a significant role in modern civilization and will continue to play a vital role towards maintaining and improving our quality of life. Particularly, these transformations have had a tremendous impacts on the agricultural, transport, energy, and pharmaceutical sectors. This field of base-metal catalysis would enjoy added benefits with the utilization of sustainable feedstock carbon sources for fine chemical synthesis. However, the dual problems of activation of thermodynamically stable precursors (ethylene, CO2, H2, CO, aldehydes, acrylates, HCN) and their highly stereoselective incorporation into other readily available substrates (1,3-dienes, alkynes, enynes) pose new challenges. In a nutshell, the development of benign catalysts for employing sustainable feedstock starting materials has the potential to transform inexpensive materials into valuable precursors for fine chemical synthesis. My dissertation work focuses on the development of scalable, atom-economical, and cost-effective catalytic methods for the preparation of value-added products relevant to fine chemicals. The overarching aims are to use sustainable feedstocks or readily available precursors, and environmentally benign chemistry. To achieve these goals, three efficient catalytic methods have been developed which employ complexes of an earth-abundant metal, cobalt, with ligands derived from naturally occurring amino acids or commercially available bis-phosphine ligands. The key to success was a systematic ligands investigation that inspired the design and synthesis of novel ligands to achieve high chemo-, regio-, and enantioselectivities. In the first methodology, a broadly applicable method affecting [2+2] cycloaddition between several alkynes and alkenyl derivatives to form cyclobutenes has been disclosed. A library of >70 nearly enantiopure cyclobutenes, which are ubiquitous motifs in bioactive compounds, have been synthesized in excellent yields. In the second methodology, ligand controlled regio-divergent enantioselective synthesis of primary and secondary homoallylic boronates (>50 examples) from readily available 1,3-dienes and a common boron reagent have been developed. Furthermore, the hydrofunctionalization of 1,3-dienes program has been extended to unprecedented enantioselective hydroacylation of 1,3-dienes. This method opens a realm to achieve the synthesis of enantiopure alpha- or beta-chiral center containing ketones. In all the mentioned transformations above, cationic Co(I)- species has been invoked as an active catalyst. To further corroborate the role of cationic Co(I)-complexes, a reliable protocol has been developed to synthesize, isolate discrete neutral and cationic Co(I)-complexes and characterized by X-ray crystallography. These isolated cationic complexes serve as an excellent single-component catalyst for heterodimerization, hydroboration, and hydroacylation, suggesting the key role of cationic Co(I)-complexes in these transformations. While developing these efficient methodologies, striking ligand, counterion, and solvent effects have been revealed along with a unique role of a cationic Co(I) intermediate in the reactions which advanced novel fundamental concepts. We believe that these cationic Co(I) complexes have broader utility in homogeneous catalysis. We hope that the rational evolution of a mechanism-based strategy that led to the eventual successful outcome and the attendant support studies will add to the burgeoning organometallic chemistry of cobalt and its applications with further implications beyond the synthetic reactions described in this dissertation.

Download or read book Recent Developments in Functional Materials for Artificial Photosynthesis written by Srabanti Ghosh and published by Royal Society of Chemistry. This book was released on 2023-03-08 with total page 383 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book will give a comprehensive overview of recently developed, multifunctional materials as visible light-driven catalysts, their mechanisms and applications in solar energy utilization and conversion.

Download or read book New and Future Developments in Catalysis written by Steven L Suib and published by Newnes. This book was released on 2013-07-19 with total page 493 pages. Available in PDF, EPUB and Kindle. Book excerpt: New and Future Developments in Catalysis is a package of seven books that compile the latest ideas concerning alternate and renewable energy sources and the role that catalysis plays in converting new renewable feedstock into biofuels and biochemicals. Both homogeneous and heterogeneous catalysts and catalytic processes will be discussed in a unified and comprehensive approach. There will be extensive cross-referencing within all volumes.The use of solar energy during various catalytic chemical processes for the production of an array of chemical products is the theme of this volume. Photocatalysis is a topic of increasing importance due to its essential role in many of today’s environmental and energy source problems. The use of solar energy for catalytic reactions results in a carbon dioxide–neutral process. All photocatalytic processes and the future developments in this area are discussed, including an economic analysis of the various processes. Offers in-depth coverage of all catalytic topics of current interest and outlines future challenges and research areas A clear and visual description of all parameters and conditions, enabling the reader to draw conclusions for a particular case Outlines the catalytic processes applicable to energy generation and design of green processes

Download or read book Metalloenzymes as Inspirational Electrocatalysts for Artificial Photosynthesis written by Andreas S. J. L. Bachmeier and published by Springer. This book was released on 2016-11-23 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes a series of investigations designed to assess the value of metalloenzymes in systems for artificial and adapted photosynthesis. The research presented explores the interplay between inherent enzyme properties such as structure, rates and thermodynamics, and the properties of the semiconducting materials to which the enzyme is attached. Author, Andreas Bachmeier provides a comprehensive introduction to the interdisciplinary field of artificial photosynthesis, allowing the reader to grasp the latest approaches being investigated, from molecular systems to heterogeneous surface catalysis. Bachmeier’s work also uses metalloenzymes to highlight the importance of reversible catalysts in removing the burden of poor electrocatalytic rates and efficiencies which are common characteristics for most artificial photosynthesis systems. Overall, this thesis provides newcomers and students in the field with evidence that metalloenzymes can be used to establish new directions in artificial photosynthesis research.

Download or read book Development of Dinuclear Metal Complexes for Catalytic Transformations in Artificial Photosynthesis written by Timothy Charles Davenport and published by . This book was released on 2012 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book From Molecules to Materials written by Elena A. Rozhkova and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This interdisciplinary book focuses on the various aspects transformation of the energy from sunlight into the chemical bonds of a fuel, known as the artificial photosynthesis, and addresses the emergent challenges connected with growing societal demands for clean and sustainable energy technologies. The editors assemble the research of world-recognized experts in the field of both molecular and materials artificial systems for energy production. Contributors cover the full scope of research on photosynthesis and related energy processes.

Download or read book Artificial Photosynthesis written by and published by Academic Press. This book was released on 2016-06-13 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt: Artificial Photosynthesis, the latest edition in the Advances in Botanical Research series, which publishes in-depth and up-to-date reviews on a wide range of topics in the plant sciences features several reviews by recognized experts on all aspects of plant genetics, biochemistry, cell biology, molecular biology, physiology, and ecology. Publishes in-depth and up-to-date reviews on a wide range of topics in plant sciences Presents the latest information on artificial photosynthesis Features a wide range of reviews by recognized experts on all aspects of plant genetics, biochemistry, cell biology, molecular biology, physiology, and ecology

Download or read book 107 1 Hearings Energy and Water Development Appropriations for 2002 Part 4 2001 written by and published by . This book was released on 2001 with total page 1476 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nanostructured Cobalt Oxide Clusters in Mesoporous Silica as Efficient Oxygen Evolving Catalysts written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The development of integrated artificial photosynthetic systems for the direct conversion of carbon dioxide and water to fuel depends on the availability of efficient and robust catalysts for the chemical transformations. Catalysts need to exhibit turnover frequency (TOF) and density (hence size) commensurate with the solar flux at ground level (1000Wm2, airmass (AM) 1.5)[1]to avoid wasting of incidentsolar photons. For example, a catalyst with a TOF of 100 s1 requires a density of one catalytic site per square nanometer. Catalysts with lower rates or taking up a larger space will require a high-surface-area, nanostructured support that affords tens to hundreds of catalytic sites per square nanometer. Furthermore, catalysts need to operate close to the thermodynamic potential of the redox reaction so that amaximum fraction of the solar photon energy is converted to chemical energy. Stability considerations favor all-inorganic oxide materials, as does avoidance of harsh reaction conditions of pH value or temperature.

Download or read book Molecular Catalysts for CO2 Fixation Reduction written by Hitoshi Ishida and published by Frontiers Media SA. This book was released on 2020-03-20 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book System Materials Nanoarchitectonics written by Yutaka Wakayama and published by Springer Nature. This book was released on 2022-01-03 with total page 334 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is the first publication to widely introduce the contributions of nanoarchitectonics to the development of functional materials and systems. The book opens up pathways to novel nanotechnology based on bottom-up techniques. In fields of nanotechnology, theoretical and practical limitations are expected in the bottom-up nanofabrication process. Instead, some supramolecular processes for nano- and microstructure formation including molecular recognition, self-assembly, and template synthesis have gained great attention as novel key technologies to break through expected limitations in current nanotechnology. This volume describes future images of nanotechnology and related materials and device science as well as practical applications for energy and biotechnology. Readers including specialists, non-specialists, graduate students, and undergraduate students can focus on the parts of the book that interest and concern them most. Target fields include materials chemistry, organic chemistry, physical chemistry, nanotechnology, and even biotechnology.

Download or read book Energy and Water Development Appropriations for 2002 Department of Energy fiscal year 2002 budget justifications written by United States. Congress. House. Committee on Appropriations. Subcommittee on Energy and Water Development and published by . This book was released on 2001 with total page 3046 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Investigation of Oxygen Evolution Reaction Catalysts written by Guangyao Gao and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sustainable energy is an important topic with increasing energy demands, worldwide. Hydrogen energy is one of the promising directions in developing new energy resources. One of the promising methods for hydrogen generation is oxygen evolution reaction (OER) process. However, because of the high energy barrier associated with oxygen evolution reaction, novel catalysts are desired to promote catalytic activity. Among others, transition metal oxides have been one of the optimal materials for oxygen evolution reaction. Recent experimental studies have evaluated the catalytic performance of cobalt oxide structures. However, the fundamental details into the mechanism of OER is largely unknown, this study is focused on providing such insights of OER using first-principle calculation with density functional theory. To overcome the underestimation of the band gap, Hubbard correction (Hubbard values U = 3.3 eV for Co, 3.7 eV for Cr) is applied to the PBE functional throughout the calculation. The Hubbard correction values are validated by comparing to the experimental band gap values and the lattice parameters.The electronic properties of pristine and Cr-substituted cobalt oxides structures were investigated by computing their band structures, density of states, and projected density of states. This study clearly reports a strong correlation between the band gap and the concentration of Cr substituted in the substrate framework. The computed band gap stays relatively constant and was consistent with the experimental values of Co3O4 for Cr concentration less than 1.25.