Rational Design Strategies for Oxide Oxygen Evolution Electrocatalysts PDF Download
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Author: Wesley Terrence Hong
Publisher:
ISBN:
Category :
Languages : en
Pages : 160
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Book Description
Understanding and mastering the kinetics of oxygen electrocatalysis is instrumental to enabling solar fuels, fuel cells, electrolyzers, and metal-air batteries. Non-precious transition metal oxides show promise as cost-effective materials in such devices. Leveraging the wealth of solid-state physics understanding developed for this class of materials in the past few decades, new theories and strategies can be explored for designing optimal catalysts. This work presents a framework for the rational design of transition-metal perovskite oxide catalysts that can accelerate the development of highly active catalysts for more efficient energy storage and conversion systems. We describe a method for the synthesis of X-ray emission, absorption, and photoelectron spectroscopy data to experimentally determine the electronic structure of oxides on an absolute energy scale, as well as extract key electronic parameters associated with the material. Using this approach, we show that the charge-transfer energy - a parameter that captures the energy configuration of oxygen and transition-metal valence electrons - is a central descriptor capable of modifying both the oxygen evolution kinetics and mechanism. Its role in determining the absolute band energies of a catalyst can rationalize the differences in the electron-transfer and proton-transfer kinetics across oxide chemistries. Furthermore, we corroborate that the charge-transfer energy is one of the most influential parameters on the oxygen evolution reaction through a statistical analysis of a multitude of structure-activity relationships. The quantitative models generated by this analysis can then be used to rapidly screen oxide materials across a wide chemical space for highthroughput materials discovery.
Author: Wesley Terrence Hong
Publisher:
ISBN:
Category :
Languages : en
Pages : 160
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Book Description
Understanding and mastering the kinetics of oxygen electrocatalysis is instrumental to enabling solar fuels, fuel cells, electrolyzers, and metal-air batteries. Non-precious transition metal oxides show promise as cost-effective materials in such devices. Leveraging the wealth of solid-state physics understanding developed for this class of materials in the past few decades, new theories and strategies can be explored for designing optimal catalysts. This work presents a framework for the rational design of transition-metal perovskite oxide catalysts that can accelerate the development of highly active catalysts for more efficient energy storage and conversion systems. We describe a method for the synthesis of X-ray emission, absorption, and photoelectron spectroscopy data to experimentally determine the electronic structure of oxides on an absolute energy scale, as well as extract key electronic parameters associated with the material. Using this approach, we show that the charge-transfer energy - a parameter that captures the energy configuration of oxygen and transition-metal valence electrons - is a central descriptor capable of modifying both the oxygen evolution kinetics and mechanism. Its role in determining the absolute band energies of a catalyst can rationalize the differences in the electron-transfer and proton-transfer kinetics across oxide chemistries. Furthermore, we corroborate that the charge-transfer energy is one of the most influential parameters on the oxygen evolution reaction through a statistical analysis of a multitude of structure-activity relationships. The quantitative models generated by this analysis can then be used to rapidly screen oxide materials across a wide chemical space for highthroughput materials discovery.
Author: Samji Samira
Publisher:
ISBN:
Category : Chemical engineering
Languages : en
Pages : 0
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Book Description
In this dissertation, a multifaceted approach involving detailed kinetic studies, an arsenal of characterization techniques, and atomistic simulations were combined to allow for interpretation of macroscopic reactivity and stability trends of heterogeneous electrocatalysts. Specifically, atomic scale insights were developed to understand the key factors that govern electrochemical transformations of molecular oxygen via its reduction and evolution reactions (ORR/OER). These oxygen-based electrochemical reactions were chosen as probe reactions because they are central for sustainable energy conversion and storage technologies in regenerative H2-fuel cells and Li-O2 batteries. Currently, these reactions are catalyzed by cost-prohibitive Pt and Ir-based catalysts, thus limiting the widespread adoption of these technologies. Non-precious metal containing non-stoichiometric mixed metal oxides of the general form An+1BnO3n+1 (A = alkaline earth/rare earth metal; B = transition metal; n = 1, 2, 3, ...∞) remain a high interest class of electrocatalytic materials for catalyzing these reactions. These oxides are compositionally versatile and can accommodate >90% of the metals in the periodic table, allowing for practically limitless opportunities to tune their catalytic performance. However, lack of effective design strategies that can link the initial oxide composition with their resulting catalytic activity and stability has hampered their development. To overcome these limitations, local surface electronic structure of the active centers in these oxides were probed both experimentally and theoretically and correlated to their resulting electrochemical activity and stability towards ORR/OER. To begin with, the effect of different 3d transition metals in these oxides, on their ORR performance was studied. It was found that the strength of metal–oxygen bonds in the surface of the oxide, as described by the oxide surface reducibility was crucial in determining their electrocatalytic performance. It was found that LaMnO3 provides the optimal metal–oxygen bond strength, consequently leading to enhanced ORR performance. Further, the differences in the metal–oxygen bond strength in these oxides was exploited to effectively tailor the electronic structure of infinitesimal amounts of 4d/5d metal cations. This was shown to switch catalytically inert Rh and supported Rh oxides into highly active cationic centers in LaNi1-xRhxO3 (0.01≤x≤0.02) for ORR. On the other hand, the surfaces of these oxides were found to be dynamic in nature during OER. Consequently, a link between the initial oxide composition and the dynamic factors that control the catalytic activity toward OER was developed. Finally, a fundamental framework to investigate electrocatalysis at solid-solid interfaces between an oxide electrocatalyst and the solid discharge products in Li-O2 batteries was also developed. The rational design strategies developed in this dissertation clearly outlines the impact of investigating the surface electronic structure of heterogenous catalysts and correlating it with their catalytic performance. Although, the insights developed here were specifically for oxygen electrocatalysis on non-stoichiometric mixed metal oxides, the principles used here can be extended to other catalytic systems, as well as other targeted reaction chemistries. This leads to a bottom-up approach of catalyst design, rather than a trial and error one
Author: S. Paddison
Publisher: The Electrochemical Society
ISBN: 1607686511
Category : Science
Languages : en
Pages : 49
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Author: Antoni Llobet
Publisher: Wiley
ISBN: 9781118413371
Category : Technology & Engineering
Languages : en
Pages : 0
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Book Description
Photocatalytic water splitting is a promising strategy for capturing energy from the sun by coupling light harvesting and the oxidation of water, in order to create clean hydrogen fuel. Thus a deep knowledge of the water oxidation catalysis field is essential to be able to come up with useful energy conversion devices based on sunlight and water splitting. Molecular Water Oxidation Catalysis: A Key Topic for New Sustainable Energy Conversion Schemes presents a comprehensive and state-of-the-art overview of water oxidation catalysis in homogeneous phase, describing in detail the most important catalysts discovered today based on first and second row transition metals. A strong emphasis is placed on the description of their performance, as well as how they work from a mechanistic perspective. In addition, a theoretical description of some of the most relevant catalysts based on DFT are presented, as well as a description of related natural systems, such as the oxygen evolving system of photosystem II and the heme chlorite-dismutase. This book is a valuable resource for researchers working on water oxidation catalysis, solar energy conversion and artificial photosynthesis, as well as for chemists and materials scientists with a broad interest in new sustainable energy conversion schemes.
Author: Tingting Zhao
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Developing cost-effective and durable electrocatalysts for the sluggish oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is at the heart of advancing energy conversion and storage technologies, such as rechargeable metal"â€air batteries. In this thesis, several strategies were investigated for this purpose, with a focus on non-noble transition metal derivatives (Mn, Co, Ni, Fe oxides/hydroxides) and functional carbon substrates (oxidized carbon nanotubes and defective graphene). The enhancement in electrochemical performance was realized by rational design of the hybrid structure. Three series of hybrids were synthesized and analyzed: (1) Manganese cobalt oxide/nitrogen-doped multiwalled carbon nanotubes hybrids were rationally integrated by fine control of surface chemistry and synthesis conditions, including tuning of functional groups at surfaces, the congruent growth of nanocrystals with controllable phases and particle sizes, and ensuring strong coupling across catalyst"â€support interfaces. The hybrid structure exhibits tunable and durable catalytic activities for both ORR and OER, with a lowest overall potential difference of 0.93 V. The long-term electrochemical activities are also sustained by rational design of hybrid structures from the nanoscale. (2) Defect-rich graphene was realized by a two-step treatment (thermal reduction and annealing) to enhance the effectiveness of ORR and OER. The dominant mechanism for the enhancement is the increased density of active sites, which can be controlled by the annealing temperature in relation to the O/C ratio, surface area and pore structure. This defective graphene substrate can reduce the amount of manganese cobalt oxide needed to achieve comparable performance against the commercial standard Pt/C, proving an effective strategy of developing cost-effective oxygen electrocatalysts. (3) Nickel-iron layered double hydroxide on defective graphene was developed for highly efficient oxygen evolution electrocatalysis. The hybrids with annealed graphene as the substrate exhibit more efficient oxygen evolution than the other graphene-based materials studied earlier and in this work, in terms of high current response, low overpotential and Tafel slope. The main reason is due to the extensive defects, high electrical conductivity and hierarchical pore size distribution. The morphology, phase and electronic state of the nickel-iron hydroxides were further tuned by the atomic ratio of Ni and Fe and the synthesis conditions, leading to a much reduced low overpotential of 285 mV and 418 mV to achieve 10 mA cm−2 and 100 mA cm−2, respectively, which is among the best oxygen evolution electrocatalysts. The thesis also reviewed the concurrent progress of this subject area, outlined the perspective of this emerging field and proposed further work.
Author: Junlei Qi
Publisher: Elsevier
ISBN: 0323898068
Category : Technology & Engineering
Languages : en
Pages : 406
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Book Description
Metal Oxides and Related Solids for Electrocatalytic Water Splitting reviews the fundamentals and strategies needed to design and fabricate metal oxide-based electrocatalysts. After an introduction to the key properties of transition metal oxides, materials engineering methods to optimize the performance of metal-oxide based electrocatalysts are discussed. Strategies reviewed include defect engineering, interface engineering and doping engineering. Other sections cover important categories of metal-oxide (and related solids) based catalysts, including layered hydroxides, metal chalcogenides, metal phosphides, metal nitrides, metal borides, and more. Each chapter introduces important properties and material design strategies, including composite and morphology design. There is also an emphasis on cost-effective materials design and fabrication for optimized performance for electrocatalytic water splitting applications. Lastly, the book touches on recently developed in-situ characterization methods applied to observe and control the material synthesis process. - Introduces metal oxide-based materials for electrocatalytic water splitting applications, including their key properties, synthesis, design and fabrication strategies - Reviews the most relevant materials design strategies, including defect engineering, interface engineering, and doping engineering - Discusses the pros and cons of metal oxide-based materials for water splitting applications to aid in materials selection
Author: Michalis Konsolakis
Publisher: Mdpi AG
ISBN: 9783036561646
Category : Science
Languages : en
Pages : 0
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Book Description
This reprinted edition of the Special Issue entitled "Rational Design of Non-Precious Metal Oxide Catalysts by Means of Advanced Synthetic and Promotional Routes" covers some of the recent advances in relation to the fabrication and fine-tuning of metal oxide catalysts by means of advanced synthetic and/or promotional routes. It consists of fourteen high-quality papers on various aspects of catalysis, related to the rational design and fine-tuning strategies during some of the most relevant applications in heterogeneous catalysis, such as N2O decomposition, the dry reforming of methane (DRM), methane combustion and partial oxidation, and selective catalytic reduction (SCR), among others.
Author: Daniel F. Abbott
Publisher:
ISBN:
Category : Catalysts
Languages : en
Pages : 153
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Book Description
The rational design of electrocatalysts is paramount to the development of electrochemical devices. In particular, modifications to the structure and electronic properties of a particular catalyst can have a strong influence on the activity and selectivity towards various electrochemical reactions or pathways. In many cases this can lead to a particular reaction pathway being opened or closed, the formation of intermediates being stabilized or inhibited, the adsorption of poisonous species being mitigated, or the removal of poisonous species being promoted. In the this dissertation the design and characterization of catalysts for electrochemical devices (fuel cells, electrolyzers, and hydrogen pumps) will be discussed with regards to tailoring the selectivity in order to promote or inhibit certain electrochemical reactions. The electrochemical reactions of primary interest will include the methanol oxidation reaction (MOR), the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen oxidation reaction (HOR).
Author: Zhuang Liu
Publisher:
ISBN:
Category :
Languages : en
Pages : 172
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Book Description
ABSTRACT OF THE DISSERTATION Rational Design of Transition Metal-Nitrogen-Carbon Electrocatalysts for Oxygen Reduction Reaction by Zhuang Liu Doctor of Philosophy in Chemical Engineering University of California, Los Angeles, 2018 Professor Yunfeng Lu, Chair The harvest and conversion of energy is of crucial importance for human civilization. Today, the fast growth in energy consumption, together with the environmental problems caused by fossil fuel usage, calls for renewable and clean energy supply, such as solar, wind, geothermal, and tidal energy. However, such energies are not consistent in both time and location, bringing energy storage on request. Intensive research has been focused on the development of electrochemical energy storage (EES) devices. Among these EES devices, hydrogen fuel cells and metal-air batteries have attracted the special attention because of their high theoretical energy densities. Yet, one major issue lies in the sluggish oxygen reduction reaction (ORR) that takes place at the cathodes. For example, the theoretical voltage of a hydrogen-oxygen fuel cell is 1.23 V (standard condition). However, the voltage output obtained under a meaningful current density is only about 0.7 V, where the voltage loss is primarily caused by the overpotential in the cathodes. Developing efficient electro-catalysts, which can lower the overpotential of ORR, is indispensable for achieving high performance devices. The state-of-the-art ORR electro-catalysts are generally based on platinum, which is limited by cost and scarcity. Developing electro-catalysts based on earth abundant metal elements is critical for large-scale application of fuel cells and metal-air batteries. Among the non-precious-metal catalysts (NPMCs) explored in recent decades, pyrolyzed iron-nitrogen-carbon (Fe-N-C) catalysts is widely regarded as the most promising candidate for replacing platinum due to their high activity. However, the traditional method for preparing Fe-N-C catalysts involves high-temperature pyrolysis of the precursors, which is a highly complex and unpredictable process. As-prepared Fe-N-C catalysts usually contain mixed chemical phases (e.g., Fe-based nanoparticles, Fe-N coordination site and various nitrogen species), as well as carbon scaffolds with random morphology. Such complexity makes it difficult to identify the active site and control the porous structure. Though progress has been made in improving their performance through delicate selection of precursors, such process is largely based on test-and-trial method, shedding little light on the understanding of the material. In this dissertation, we designed a novel "post iron decoration" synthetic strategy towards efficient Fe-N-C catalysts, which de-convolutes the growth of iron and nitrogen species, enables the rational design of the catalyst structure, and provides a series of effective model materials for active site probing. Specifically, liquid iron penta-carbonyl was used to wet the surface of mesoporous N-doped carbon spheres (NMC), whose porous structure is determined by the template used for preparation. The obtained Fe(CO)5/NMC complex was then pyrolyzed to generate the Fe/NMC catalysts. Through comparative study and thorough material characterization, we demonstrated that the pyridinic-N of NMC anchors the Fe atoms to form Fe-Nx active sites during pyrolysis, while the graphitic-N remains ORR active. The excessive Fe atoms were aggregated forming fine nanoparticles, which were subsequently oxidized forming amorphous-iron oxide/iron crystal core-shell structure. All the composing elements of Fe/NMC catalysts are uniformly distributed on the NMC scaffold, whose porous structure is shown to be not affected by Fe decoration, guaranteeing the effective exposure of active sites. The best performing Fe/NMC catalysts exhibited a high half-wave potential of 0.862 V, which is close to that of the benchmark 40% Pt/C catalyst. Such high activity is primarily attributed to the Fe-Nx active sites in the catalysts. While the surface oxidized Fe crystallites though not being the major active site, is revealed to catalyze the reduction of HO2-, the 2e ORR product, facilitating the 4e reduction of oxygen. Finally, such synthetic strategy is successfully extended to prepare other Me-N-C materials. Based on the established understanding of the active sites, we then complexed the active Fe(CO)5 molecules with a N-rich metal-organic framework (ZIF-8) to form a precursor, which was subsequently pyrolyzed to form Fe-NC catalysts. During the pyrolysis, Fe(CO)5 reacts homogeneously with the ZIF-8 scaffold, leading to the formation of uniform distribution of Fe-related active sites on the N-rich porous carbon derived from ZIF-8. The zinc atoms in the crystalline structure of ZIF-8 serves as thermo-sacrificial template, resulting in the formation of hierarchical pores that provide abundant easily accessible ORR active sites. In virtue of these advantageous features, the best performing Fe-NC catalyst exhibited a high half-wave potential of 0.91 V in rotating disk electrode experiment in 0.1 M NaOH. Furthermore, zinc-air battery constructed with Fe-NC-900-M as the cathode catalyst exhibited high open-circuit voltage (1.5 V) and a peak power density of 271 mW cm-2, which outperforms those made with 40% Pt/C catalyst (1.48 V, 1.19 V and 242 mW cm-2), and most noble-metal free ORR catalysts reported so far. Finally, such a synthetic method is economic and easily-scalable, offering possibility for further activity and durability improvement.
Author: Jianmin Ma
Publisher: John Wiley & Sons
ISBN: 352734859X
Category : Technology & Engineering
Languages : en
Pages : 596
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Book Description
Explore green catalytic reactions with this reference from a renowned leader in the field Green reactions—like photo-, photoelectro-, and electro-catalytic reactions—offer viable technologies to solve difficult problems without significant damage to the environment. In particular, some gas-involved reactions are especially useful in the creation of liquid fuels and cost-effective products. In Photo- and Electro-Catalytic Processes: Water Splitting, N2 Fixing, CO2 Reduction, award-winning researcher Jianmin Ma delivers a comprehensive overview of photo-, electro-, and photoelectron-catalysts in a variety of processes, including O2 reduction, CO2 reduction, N2 reduction, H2 production, water oxidation, oxygen evolution, and hydrogen evolution. The book offers detailed information on the underlying mechanisms, costs, and synthetic methods of catalysts. Filled with authoritative and critical information on green catalytic processes that promise to answer many of our most pressing energy and environmental questions, this book also includes: Thorough introductions to electrocatalytic oxygen reduction and evolution reactions, as well as electrocatalytic hydrogen evolution reactions Comprehensive explorations of electrocatalytic water splitting, CO2 reduction, and N2 reduction Practical discussions of photoelectrocatalytic H2 production, water splitting, and CO2 reduction In-depth examinations of photoelectrochemical oxygen evolution and nitrogen reduction Perfect for catalytic chemists and photochemists, Photo- and Electro-Catalytic Processes: Water Splitting, N2 Fixing, CO2 Reduction also belongs in the libraries of materials scientists and inorganic chemists seeking a one-stop resource on the novel aspects of photo-, electro-, and photoelectro-catalytic reactions.
