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Author: Chuhyon John Eom Publisher: ISBN: Category : Languages : en Pages : 123
Book Description
The structure-property relationship is a foundational concept of materials science and engineering. Tuning the catalytic properties of materials by varying their structural properties like stoichiometry and crystal facets have been integral to advances in electrocatalysis. Traditionally, these studies rely on ex situ, bulk structural characterizations to describe catalytic properties. Catalysis, however, occurs on a dynamic catalytic surface sensitive to its local environment. This dissertation uses in situ spectroscopy of metal oxide electrocatalysts to better capture the intricacies of such catalyst structure-property relationships. La2/3S1/3rMnO3 films are grown using molecular beam epitaxy for a controlled study on the effects of surface and sub-surface structure of metal oxides on the oxygen reduction reaction (ORR) catalysis. Ambient pressure X-ray photoelectron spectroscopy of the films show that the surface and sub-surface structures control the balance between electronic benefits vs. parasitic surface reactions for the ORR. The low atomic number group of an amorphous cobalt oxide catalyst in a phosphate network (CoPi) is studied using home-built stimulated Raman spectroscopy (SRS). In situ SRS reveals previously unreported phosphate motifs in CoPi under oxygen evolution reaction conditions. Isotopic studies show that the phosphate structure is intimately linked to the aqueous environment with implications for the catalyst microstructure and deposition. Extensions of the dissertation on the in situ spectroscopy of a quinone electrochemical systems is discussed in the end.
Author: Chuhyon John Eom Publisher: ISBN: Category : Languages : en Pages : 123
Book Description
The structure-property relationship is a foundational concept of materials science and engineering. Tuning the catalytic properties of materials by varying their structural properties like stoichiometry and crystal facets have been integral to advances in electrocatalysis. Traditionally, these studies rely on ex situ, bulk structural characterizations to describe catalytic properties. Catalysis, however, occurs on a dynamic catalytic surface sensitive to its local environment. This dissertation uses in situ spectroscopy of metal oxide electrocatalysts to better capture the intricacies of such catalyst structure-property relationships. La2/3S1/3rMnO3 films are grown using molecular beam epitaxy for a controlled study on the effects of surface and sub-surface structure of metal oxides on the oxygen reduction reaction (ORR) catalysis. Ambient pressure X-ray photoelectron spectroscopy of the films show that the surface and sub-surface structures control the balance between electronic benefits vs. parasitic surface reactions for the ORR. The low atomic number group of an amorphous cobalt oxide catalyst in a phosphate network (CoPi) is studied using home-built stimulated Raman spectroscopy (SRS). In situ SRS reveals previously unreported phosphate motifs in CoPi under oxygen evolution reaction conditions. Isotopic studies show that the phosphate structure is intimately linked to the aqueous environment with implications for the catalyst microstructure and deposition. Extensions of the dissertation on the in situ spectroscopy of a quinone electrochemical systems is discussed in the end.
Author: H.H. Kung Publisher: Elsevier ISBN: 0080887422 Category : Science Languages : en Pages : 299
Book Description
In this book the author presents an up-to-date summary of existing information on the structure, electronic properties, chemistry and catalytic properties of transition metal oxides.The subjects covered in the book can be divided into three sections. The first (chapters 1 to 3) covers the structural, physical, magnetic, and electronic properties of transition metal oxides. Although the emphasis is on surface properties, relevant bulk properties are also discussed. The second section (chapters 4 to 7) covers surface chemical properties. It includes topics that describe the importance of surface coordinative unsaturation in adsorption, the formation of surface acidity and the role of acidity in determining surface chemical properties, the nature and reactivities of adsorbed oxygen, and the surface chemistry in the reduction of oxides. The third section (chapters 8 to 14) is on the catalytic properties. Various catalytic reactions including decomposition, hydrogenation, isomerization, metathesis, selective oxidation, and reactions involving carbon oxides are discussed. Emphasis is placed more on reaction mechanisms and the role of catalysts than on kinetics and processes. Chapters on the preparation of oxide catalysts and on photo-assisted processes are also included. Whenever appropriate, relationships between various topics are indicated.Written for surface physicists, chemists, and catalytic engineers, the book will serve as a useful source of information for investigators and as a comprehensive overview of the subject for graduate students.
Author: Speranta Tanasescu Publisher: BoD – Books on Demand ISBN: 1789854512 Category : Science Languages : en Pages : 104
Book Description
The interrelation among composition, microstructure, and properties of stoichiometric and nonstoichiometric compounds is a major field of research for both scientific and technological reasons. As such, this book focuses on metal oxides, which present a large diversity of electrical, magnetic, optical, optoelectronic, thermal, electrochemical, and catalytic properties, making them suitable for a wide range of applications. By bringing together scientific contributions with special emphasis on the interrelations between materials chemistry, processing, microstructures, and properties of stoichiometric and nonstoichiometric metal oxides, this book highlights the importance of tightly integrating high-throughput experiments (including both synthesis and characterization) and efficient and robust theory for the design of advanced materials.
Author: Qingsheng Gao Publisher: World Scientific ISBN: 1800611587 Category : Science Languages : en Pages : 606
Book Description
With interdisciplinary perspectives from internationally renowned experts, Noble-Metal-Free Electrocatalysts for Hydrogen Energy is one of the most authoritative references to focus solely on state-of-the-art knowledge of noble-metal-free electrocatalysts, as well as their nanostructures and unique properties. The chapters within contain cutting-edge breakthroughs, horizons, and insights into functional materials for energy applications.This book contains over 3000 references and 200 figures, and is a highly valuable resource for scientists, students, and engineers working in the fields of electrochemistry, catalysis, fuel cells, batteries, and supercapacitors.
Author: Shuai Zhao Publisher: ISBN: Category : Electronic dissertations Languages : en Pages :
Book Description
Fuel cells, one of the most widely studied electrochemical energy conversion devices, together with electrolyzers, a promising energy storage system for natural renewable energy and source of purified hydrogen, have attracted significant research attention in recent years as the demand for energy continues to increase with no end to this energy expansion in sight. However, electrochemical reactions occurring at oxygen electrodes such as the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) have very slow kinetics, which has limited the industrialization of both fuel cells and electrolyzers because slow kinetics leads directly high reaction overpotentials. Metal oxides have been widely adopted in terms of electrocatalysts for these oxygen reactions, either as as a support to enhance the stability or activity of platinum, or as the direct catalysts for ORR and OER in alkaline media. However, what is not known is how and why metal oxides as support materials can influence the performance of precious metals through their interactions, what the active sites are for different electrochemical reactions and how to control the desired phases by manipulating the synthesis conditions. This study will probe these very important questions. Chapter 1 of this work provides a background into the ORR/OER mechanism, active sites, and catalyst candidates in electrochemical devices. Chapter 2 presents experimental approaches including material synthesis, and both physical and electrochemical characterization. Chapters 3 and 4 of this study investigate doped metal carbides and metal oxides as support materials for platinum and iridium catalysts for the ORR and OER, respectively, in acidic electrolytes. The Chapter 3 is an investigation of tungsten carbide modified with titanium as a potential non-carbon support for platinum during the ORR in acid media. Chapter 4 discusses the relationship between the synthesis parameters of iridium/iridium oxide supported on titanium-doped tungsten oxide and its durability both ex-situ in a three-electrode cell on a rotating disk electrode (RDE) and in-situ in an operating electrolyzer. Chapter 5 discusses a new method to determine the electrochemically active area of iridium oxide, one of the most common anode catalysts in commercial PEM electrolyzers, in-situ through its electrochemical psuedocapacitance. Chapter 6 probes the performance and function of tin-doped indium oxides (ITO) as a support for platinum ORR catalyst in alkaline media. Metal-support interactions were studied mainly through X-ray photoelectron spectroscopy and electrochemical measurements. Chapter 7 focuses on the electrocatalysis of carbon nanotube (CNT)-supported cobalt oxide for both oxygen reduction and evolution reactions in alkaline media. An optimized procedure to produce a highly stable and active bifunctional ORR/OER hybrid catalyst was developed along with an understanding of the impact of metal oxide anchoring sites and synthesis parameters on catalyst durability. This part of the study provides novel perspectives for the design of carbon-based, hybrid materials and insight into the synthesis-property relationships for these and future electrocatalysts. In summary, this work has studied metal oxides as catalysts and support materials for precious metals during aqueous oxygen reactions. Wherever possible, the fundamental cause for their behavior, including enhanced electrocatalytic activity and durability, was probed thoroughly through physical and electrochemical characterization.
Author: J.L.G. Fierro Publisher: CRC Press ISBN: 9780824723712 Category : Science Languages : en Pages : 808
Book Description
The chemistry of metals has traditionally been more understood than that of its oxides. As catalytic applications continue to grow in a variety of disciplines, Metal Oxides: Chemistry and Applications offers a timely account of transition-metal oxides (TMO), one of the most important classes of metal oxides, in the context of catalysis. The first part of the book examines the crystal and electronic structure, stoichiometry and composition, redox properties, acid-base character, and cation valence states, as well as new approaches to the preparation of ordered TMO with extended structure of texturally defined systems. The second part compiles some practical aspects of TMO applications in materials science, chemical sensing, analytical chemistry, solid-state chemistry, microelectronics, nanotechnology, environmental decontamination, and fuel cells. The book examines many types of reactions - such as dehydration, reduction, selective oxidations, olefin metathesis, VOC removal, photo- and electrocatalysis, and water splitting - to elucidate how chemical composition and optical, magnetic, and structural properties of oxides affect their surface reactivity in catalysis. Drawing insight from leading international experts, Metal Oxides: Chemistry and Applications is a comprehensive and interdisciplinary reference for researchers that may also be used by newcomers as a guide to the field.
Author: Iflah Laraib Publisher: ISBN: Category : Languages : en Pages : 125
Book Description
Finally, we analyze the performance of different functionals in describing the electronic structure of several metal oxides, focusing on band gap, ionization potential (IP), and electron affinity (EA). We employ methods that go beyond the semi(local) approximations in density functional theory to inspect how ionization potentials and electron affinities are corrected, discussing in particular the performance of the meta-GGA SCAN, DFT+U, and hybrid functionals in the description of some representative semiconductors, band insulators, and Mott insulators, by comparing with available experimental data. We find that with a careful choice of U, DFT+U does correct band gaps in most cases, however, it often leads to wrong descriptions of IP and EA; whereas the screened hybrid functional of Heyd-Scuseria-Ernzerhof with appropriate mixing parameter, leads to accurate description of IP and EA in most cases. Our work indicates that interpretations of widely used high-throughput screening of materials for catalysis, photovoltaics, or batteries (where IP and EA, and band gaps are crucial parameters) based on the computationally inexpensive DFT+U method should be taken with great care.
Author: Grant Bunker Publisher: Cambridge University Press ISBN: 1139485091 Category : Science Languages : en Pages : 269
Book Description
X-ray absorption fine structure spectroscopy (XAFS) is a powerful and versatile technique for studying structures of materials in chemistry, physics, biology and other fields. This textbook is a comprehensive, practical guide to carrying out and interpreting XAFS experiments. Assuming only undergraduate-level physics and mathematics, the textbook is ideally suited for graduate students in physics and chemistry starting XAFS-based research. It contains concise executable example programs in Mathematica 7. Supplementary material available at www.cambridge.org/9780521767750 includes Mathematica code from the book, related Mathematica programs, and worked data analysis examples. The textbook addresses experiment, theory, and data analysis, but is not tied to specific data analysis programs or philosophies. This makes it accessible to a broad audience in the sciences, and a useful guide for researchers entering the subject.
Author: Tatsumi Ishihara Publisher: Springer Science & Business Media ISBN: 0387777083 Category : Technology & Engineering Languages : en Pages : 310
Book Description
Fuel cell technology is quite promising for conversion of chemical energy of hydrocarbon fuels into electricity without forming air pollutants. There are several types of fuel cells: polymer electrolyte fuel cell (PEFC), phosphoric acid fuel cell (PAFC), molten carbonate fuel cell (MCFC), solid oxide fuel cell (SOFC), and alkaline fuel cell (AFC). Among these, SOFCs are the most efficient and have various advantages such as flexibility in fuel, high reliability, simple balance of plant (BOP), and a long history. Therefore, SOFC technology is attracting much attention as a power plant and is now close to marketing as a combined heat and power generation system. From the beginning of SOFC development, many perovskite oxides have been used for SOFC components; for example, LaMnO -based oxide for the cathode and 3 LaCrO for the interconnect are the most well known materials for SOFCs. The 3 current SOFCs operate at temperatures higher than 1073 K. However, lowering the operating temperature of SOFCs is an important goal for further SOFC development. Reliability, durability, and stability of the SOFCs could be greatly improved by decreasing their operating temperature. In addition, a lower operating temperature is also beneficial for shortening the startup time and decreasing energy loss from heat radiation. For this purpose, faster oxide ion conductors are required to replace the conventional Y O -stabilized ZrO 2 3 2 electrolyte. A new class of electrolytes such as LaGaO is considered to be 3 highly useful for intermediate-temperature SOFCs.
Author: Chuhyon John Eom
Author: Chuhyon John Eom
Author: H.H. Kung
Author: Speranta Tanasescu
Author: Qingsheng Gao
Author: Shuai Zhao
Author: J.L.G. Fierro
Author: Iflah Laraib
Author: Héctor D. Abruña
Author: Grant Bunker
Author: Tatsumi Ishihara