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Author: Rui Zeng
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Electrocatalysis is the keystone to realize the transition from a fossil fuels-based energy landscape to one dominated by renewable energy sources. However, the sluggish reaction kinetics and low selectivity have severely limited their broad application. In this dissertation, I aim to advance electrocatalysis by combining atomistic insights to design high-performance electrocatalysts, and operando methods to reveal dynamic changes of electrocatalysts and reactants/products under real-time electrochemical conditions.As one of the most valuable operando techniques for electrocatalysis, differential electrochemical mass spectrometry (DEMS) was extensively employed to identify the potential dependent dynamic formation of gaseous or volatile products during the formic acid oxidation and alkene hydrogenation reactions. The successful employment of a dual-thin-layer flow cell enabled quantification of the current efficiencies of the main products and side products in the oxidation of formic acid, catalyzed by a series of Pt-Fe-Cu intermetallics. Lattice strain was proposed to account for the observed differences in current efficiencies based on a dual-pathway mechanism. DEMS was further used to evaluate alkene hydrogenation catalyzed by cobalt complexes, in which hydrogen signals were monitored as key products. The suppressed hydrogen evolution along with increased Faradaic current provided compelling evidence for alkene hydrogenation. Furthermore, the effects of electronic properties of catalysts and alkene structures on alkene hydrogenation efficiency were systematically investigated. Developing non-precious electrocatalysts for the sluggish kinetics of the oxygen reduction reaction (ORR) is regarded as one of the key bottlenecks for anion exchange membrane fuel cells (AEMFCs). I demonstrated that cobalt nitride electrocatalysts could overcome the conductivity challenge of oxide counterparts and enhance ORR performance by combining a conductive nitride core and an active oxide shell. Further, a systematic study of a family of transition metal nitrides identified cobalt nitride as the most active single metal nitride ORR electrocatalyst, which was in turn extensively evaluated by operando X-ray absorption spectroscopy during operating conditions. To unveil the underlying structure-property relationships in transition metal nitride electrocatalysts, we successfully synthesized well-defined manganese nitride nanocuboids and enriched an atomistic understanding of the interface between the surface oxide and the nitride core. A combination of theoretical calculations and microscopic study revealed that the ligand effects of the nitride core played a major role in determining the ORR performance of the surface oxide, rather than the effects of the applied tensile strain. Finally, I showed that a rigorous and systematic study of single-crystalline metal oxide/nitrides could benefit mechanistic understanding of ORR electrocatalysis for transition metal-based materials.
Author: Rui Zeng
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Electrocatalysis is the keystone to realize the transition from a fossil fuels-based energy landscape to one dominated by renewable energy sources. However, the sluggish reaction kinetics and low selectivity have severely limited their broad application. In this dissertation, I aim to advance electrocatalysis by combining atomistic insights to design high-performance electrocatalysts, and operando methods to reveal dynamic changes of electrocatalysts and reactants/products under real-time electrochemical conditions.As one of the most valuable operando techniques for electrocatalysis, differential electrochemical mass spectrometry (DEMS) was extensively employed to identify the potential dependent dynamic formation of gaseous or volatile products during the formic acid oxidation and alkene hydrogenation reactions. The successful employment of a dual-thin-layer flow cell enabled quantification of the current efficiencies of the main products and side products in the oxidation of formic acid, catalyzed by a series of Pt-Fe-Cu intermetallics. Lattice strain was proposed to account for the observed differences in current efficiencies based on a dual-pathway mechanism. DEMS was further used to evaluate alkene hydrogenation catalyzed by cobalt complexes, in which hydrogen signals were monitored as key products. The suppressed hydrogen evolution along with increased Faradaic current provided compelling evidence for alkene hydrogenation. Furthermore, the effects of electronic properties of catalysts and alkene structures on alkene hydrogenation efficiency were systematically investigated. Developing non-precious electrocatalysts for the sluggish kinetics of the oxygen reduction reaction (ORR) is regarded as one of the key bottlenecks for anion exchange membrane fuel cells (AEMFCs). I demonstrated that cobalt nitride electrocatalysts could overcome the conductivity challenge of oxide counterparts and enhance ORR performance by combining a conductive nitride core and an active oxide shell. Further, a systematic study of a family of transition metal nitrides identified cobalt nitride as the most active single metal nitride ORR electrocatalyst, which was in turn extensively evaluated by operando X-ray absorption spectroscopy during operating conditions. To unveil the underlying structure-property relationships in transition metal nitride electrocatalysts, we successfully synthesized well-defined manganese nitride nanocuboids and enriched an atomistic understanding of the interface between the surface oxide and the nitride core. A combination of theoretical calculations and microscopic study revealed that the ligand effects of the nitride core played a major role in determining the ORR performance of the surface oxide, rather than the effects of the applied tensile strain. Finally, I showed that a rigorous and systematic study of single-crystalline metal oxide/nitrides could benefit mechanistic understanding of ORR electrocatalysis for transition metal-based materials.
Author: Yao Yang
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Electrocatalysis has been the cornerstone for enhancing energy efficiency, minimizing environmental impacts and carbon emissions, and enabling a more sustainable way of meeting global energy needs. Elucidating the structure and reaction mechanisms of electrocatalysts at electrode-electrolyte interfaces is fundamental for advancing renewable energy technologies, including fuel cells, and water electrolyzers, among others. One of the fundamental challenges in electrocatalysis is understanding how to activate and sustain electrocatalytic activity, under operating conditions, for extended time periods, which calls for the use of in situ/operando methods. This thesis first introduces the design and understanding of electrocatalysts for alkaline fuel cells since they enable the use of non-precious metals to catalyze the sluggish oxygen reduction reaction (ORR) at the cathode. Metal oxide-based ORR electrocatalysts, synthesized by a hydrothermal method, in particular, Mn-Co spinel nanoparticles, have demonstrated over 1 W/cm2 benchmark peak power density with a Pt-based anode and a record 200 mW/cm2 with a Ni-based anode for a completely non-precious metal-containing alkaline fuel cell, in membrane electrode assembly (MEA) measurements. Analytical scanning transmission electron microscopy (STEM) has been extensively employed to resolve the heterogeneous crystal structures and chemical environments at the atomic scale. Operando X-ray absorption spectroscopy (XAS) methods revealed that the superior performance of Mn-Co spinels in low humidity, relative to Pt, originates from synergistic effects in which the Mn sites bind O2 while the Co sites activate H2O to facilitate the proton-coupled electron transfer process. Moving beyond oxides, we have developed nitride-core oxide-shell Co4N/C and Pd-based alloys as ORR electrocatalysts for high-power alkaline fuel cells. The second part of this thesis focuses on operando studies of electrochemical interfaces. In situ heating STEM and heating X-ray diffraction were used to track the dynamic order-disorder phase transition of Pt3Co intermetallic ORR catalysts during annealing and quantify the degree of ordering as a key structural factor for long-term MEA durability. This thesis then presents the efforts to tackle a grand challenge in physical chemistry : understanding and spatially resolving the electrochemical double layer (EDL) at electrolyte/nanocrystal electrode interfaces. Preliminary studies, with heavy halide anion and/or alkali cations as chemical probes, while promising, have yet to provide compelling evidences of potential-dependent changes of ionic distributions. However, the pursuit of these EDL studies led to the unexpected observation of cathodic corrosion, an enigmatic electrochemical process in which noble metal electrodes corrode under sufficiently reducing potentials. I employed operando EC-STEM to reveal that cathodic corrosion at solid-liquid-gas interfaces yields significantly higher levels of structural degradation for nanocrystals than bulk electrodes. The dynamic evolution of morphology, composition, and structural information was retrieved by analytical and 4D-STEM. Such microscopic studies can provide unprecedented insights into the structural evolution of nanoscale electrocatalysts during electrochemical reactions under highly reducing potentials, such as CO2 and N2 reduction.
Author: Inamuddin
Publisher: Springer Nature
ISBN: 3030271617
Category : Technology & Engineering
Languages : en
Pages : 469
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Book Description
This book explores key parameters, properties and fundamental concepts of electrocatalysis. It also discusses the engineering strategies, current applications in fuel-cells, water-splitting, metal-ion batteries, and fuel generation. This book elucidates entire category viewpoints together with industrial applications. Therefore, all the sections of this book emphasize the recent advances of different types of electrocatalysts, current challenges, and state-of-the-art studies through detailed reviews. This book is the result of commitments by numerous experts in the field from various backgrounds and expertise and appeals to industrialists, researchers, scientists and in addition understudies from various teaches.
Author: Perla B. Balbuena
Publisher: Springer Science & Business Media
ISBN: 1441955941
Category : Science
Languages : en
Pages : 597
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Book Description
Topics in Number 50 include: " Investigation of alloy cathode Electrocatalysts " A model Hamiltonian that incorporates the solvent effect to gas-phase density functional theory (DFT) calculations " DFT-based theoretical analysis of ORR mechanisms " Structure of the polymer electrolyte membranes (PEM) " ORR investigated through a DFT-Green function analysis of small clusters " Electrocatalytic oxidation and hydrogenation of chemisorbed aromatic compounds on palladium Electrodes " New models that connect the continuum descriptions with atomistic Monte Carlo simulations " ORR reaction in acid revisited through DFT studies that address the complexity of Pt-based alloys in electrocatalytic processes " Use of surface science methods and electrochemical techniques to elucidate reaction mechanisms in electrocatalytic processes " In-situ synchrotron spectroscopy to analyze electrocatalysts dispersed on nanomaterials From reviews of previous volumes: "Continues the valuable service that has been rendered by the Modern Aspects series."--Journal of Electroanalytical Chemistry "Extremely well-referenced and very readable ... Maintains the overall high standards of the series." --Journal of the American Chemical Society.
Author: James Joseph Burton
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 360
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Book Description
Advanced Materials in Catalysis is a collection of materials that discusses various catalysts. The book presents the physical and chemical properties that indicate that a particular class of materials may be of catalytic interest. The text first covers bimetallic catalysts, and then proceeds to examining the catalytic properties of compounds such as graphite intercalation compounds; oxides with the scheelite structure; and synthetic layered silicates and aluminosilicate. The book also covers reduction catalysts, biological catalysts, and monolithic catalyst supports. The selection will be of g ...
Author: György Inzelt
Publisher: Springer Science & Business Media
ISBN: 3642361889
Category : Science
Languages : en
Pages : 352
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Book Description
Reference Electrodes are a crucial part of any electrochemical system, yet an up-to-date and comprehensive handbook is long overdue. Here, an experienced team of electrochemists provides an in-depth source of information and data for the proper choice and construction of reference electrodes. This includes all kinds of applications such as aqueous and non-aqueous solutions, ionic liquids, glass melts, solid electrolyte systems, and membrane electrodes. Advanced technologies such as miniaturized, conducting-polymer-based, screen-printed or disposable reference electrodes are also covered. Essential know-how is clearly presented and illustrated with almost 200 figures.
Author: P.L Gai
Publisher: CRC Press
ISBN: 1420034413
Category : Science
Languages : en
Pages : 243
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Book Description
Catalysis is one of the most important technologies in the industrial world, controlling more than 90% of industrial chemical processes and essential for large-scale production of plastics and fuel. Exploring the most common type of catalysis used in industry, Electron Microscopy in Heterogeneous Catalysis provides a coherent account of heterogeneo
Author: Heinz Frei
Publisher: Royal Society of Chemistry
ISBN: 1839163712
Category : Technology & Engineering
Languages : en
Pages : 379
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Book Description
Ultrathin metal oxide layers have emerged in recent years as a powerful approach for substantially enhancing the performance of photo, electro, or thermal catalytic systems for energy, in some cases even enabling the use of highly attractive materials previously found unsuitable. This development is due to the confluence of new synthetic preparation methods for ultrathin oxide layers and a more advanced understanding of interfacial phenomena on the nano and atomic scale. This book brings together the fundamentals and applications of ultrathin oxide layers while highlighting connections and future opportunities with the intent of accelerating the use of these materials and techniques for new and emerging applications of catalysis for energy. It comprehensively covers the state-of-the-art synthetic methods of ultrathin oxide layers, their structural and functional characterization, and the broad range of applications in the field of catalysis for energy. Edited by leaders in the field, and with contributions from global experts, this title will be of interest to graduate students and researchers across materials science and chemistry who are interested in ultrathin oxide layers and their applications in solar energy conversion, renewable energy, photocatalysis, electrocatalysis and protective coatings.
Author: Bruce J Berne
Publisher: World Scientific
ISBN: 9814496057
Category : Science
Languages : en
Pages : 881
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Book Description
The school held at Villa Marigola, Lerici, Italy, in July 1997 was very much an educational experiment aimed not just at teaching a new generation of students the latest developments in computer simulation methods and theory, but also at bringing together researchers from the condensed matter computer simulation community, the biophysical chemistry community and the quantum dynamics community to confront the shared problem: the development of methods to treat the dynamics of quantum condensed phase systems.This volume collects the lectures delivered there. Due to the focus of the school, the contributions divide along natural lines into two broad groups: (1) the most sophisticated forms of the art of computer simulation, including biased phase space sampling schemes, methods which address the multiplicity of time scales in condensed phase problems, and static equilibrium methods for treating quantum systems; (2) the contributions on quantum dynamics, including methods for mixing quantum and classical dynamics in condensed phase simulations and methods capable of treating all degrees of freedom quantum-mechanically.
Author: Richard C. Alkire
Publisher: John Wiley & Sons
ISBN: 3527680454
Category : Science
Languages : en
Pages : 315
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Book Description
Catalysts speed up a chemical reaction or allow for reactions to take place that would not otherwise occur. The chemical nature of a catalyst and its structure are crucial for interactions with reaction intermediates. An electrocatalyst is used in an electrochemical reaction, for example in a fuel cell to produce electricity. In this case, reaction rates are also dependent on the electrode potential and the structure of the electrical double-layer. This work provides a valuable overview of this rapidly developing field by focusing on the aspects that drive the research of today and tomorrow. Key topics are discussed by leading experts, making this book a must-have for many scientists of the field with backgrounds in different disciplines, including chemistry, physics, biochemistry, engineering as well as surface and materials science. This book is volume XIV in the series "Advances in Electrochemical Sciences and Engineering".
