Download or read book Synthesis and Characterization of Mn Oxide Based Electrocatalysts for the Oxygen Reduction Reaction in the Zn Air Batteries written by 李柏潔 and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Design and Engineering of Hierarchically Porous Transition Metal based Electrocatalysts for Rechargeable Zn air Batteries written by Moon Gyu Park and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Electrochemical oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are the critical cathodic and anodic reactions, respectively, in electrically rechargeable Zn-air battery. With a variety of advantages including relatively high energy density (1218 Wh kg-1), the abundance of zinc in the earth, and secure handling and safe operation, electrically rechargeable (secondary) Zn-air battery technology has been regarded as highly promising energy applications in consumer electronics, electric vehicles, and smart grid storage. Zn-air batteries consist of not only zinc anode, polymer separator, and an alkaline electrolyte that are typical battery components, but also air-breathing cathode that makes Zn-"air" battery unique technology. Unlike other general battery systems such as lithium-ion batteries, there is no active material stored in cathode, but gaseous oxygen molecules in the air are used as the fuel for energy-generating reaction in the air cathode of Zn-air technology. The reactions occurring during battery discharge and charge are ORR and OER, respectively, which are mostly dominating the overall energy efficiency of the Zn-air battery system due to their intrinsically sluggish kinetics. The high energy barrier attributed to conversions between oxygen molecules diffused from the air and hydroxide ions in the electrolyte at the thin layer of the electrode leads to low charge/discharge energy efficiency and insufficient cycle stability hindering the commercialization of rechargeable Zn-air batteries to the market. Therefore, it is necessarily required to facilitate the slow kinetics of oxygen electrocatalytic reactions by using bifunctionally active and durable oxygen electrocatalyst materials to progress the reactions at practically viable and stable rates. With the use of bifunctional oxygen catalysts, kinetics of ORR and OER can be improved, leading to enhancement of Zn-air battery performances such as higher operating voltage and longer battery cycling life. The current best-known catalysts for ORR and OER are noble metals, including platinum (Pt) and iridium (Ir), respectively. However, high cost and scarcity of the precious metal-based catalysts hinder their employment in large scale energy applications. Furthermore, the electrochemical stability of these materials is well known to be very insufficient for long term usage even under typical device operating conditions. Therefore, the development of non-precious transition metal-based electrocatalysts has significantly been a momentous research field. Along with this movement, the facile synthesis and inexpensive preparation of highly active and durable electrocatalysts will take the top priority for the fulfillment of practically available rechargeable Zn-air battery technology in a variety of energy applications from portable electronics to electric vehicles and smart grid storage systems. In this work, novel design strategies of bifunctionally active and durable electrocatalysts possessing robust three-dimensional framework with hierarchical porosity are presented. A porous structure with a large surface area is essential to improve the oxygen electrocatalysis since the oxygen reactions take place at the surface of materials, where active sites reside, and thereby the large surface indicating plenty of catalytically active sites enhances kinetics of the reactions. Additionally, the porous architecture facilitates diffusion of oxygen gas molecules during the oxygen electrocatalysis, leading to enhanced mass transport of reactants and reduced overpotentials for ORR and OER polarizations, eventually resulting in improved activities. In addition to the improvement of activities, electrochemical stability is an essential fundamental property for the rational design of electrocatalysts. Thus, the 3D porous structure must have robust framework which can endure the highly oxidative environment in OER potential range. Therefore, the work presented in this thesis is aiming for the design and engineering of hierarchically porous transition metal-based electrocatalysts involving high porosity as well as electrocatalytically robust frameworks to improve the oxygen electrocatalytic activities and durability and thereby put the rechargeable Zn-air battery technology at a commercially viable level. In the first study, a facile polymer template-derived method has been used to synthesize three-dimensionally ordered meso/macro-porous (3DOM) spinel cobalt oxide as a bifunctional oxygen electrocatalyst. Physicochemical characterizations have revealed the morphology of the designed electrocatalyst to be a hierarchically meso/macro-porous metal oxide framework. As investigated by electrochemical characterizations, 3DOM Co3O4 shows far enhanced ORR and OER activities with improved kinetics compared to the bulk material. The enhancement is majorly attributed to the five times higher specific surface area and significantly greater pore volume, leading to the increased number of catalytic active sites and facilitated diffusion of oxygen molecules into and out of the structure, respectively. Moreover, the robust frameworks of 3DOM Co3O4 helps to withstand harsh cycling environments by exhibiting significantly small performance reduction and retaining the original morphology. The improved oxygen electrocatalytic activity and durability have been well demonstrated in the rechargeable Zn-air battery system. 3DOM Co3O4 presents remarkably enhanced rechargeability over 200 cycles while retaining quite comparable operating voltage gap in comparison with the precious benchmark catalyst. In the second study, palladium (Pd) nanoparticle is deposited on the surface of 3DOM Co3O4 via a simple chemical reduction process. The morphological advantages of the 3DOM framework, as confirmed in the previous study, are expected to facilitate diffusion of oxygen molecules into and out of the structure leading to the decreased overpotentials during ORR and OER. However, using metal oxides as electrocatalysts restricts fast electron transfer leading to limited activity for oxygen catalysis due to their intrinsically low electrical conductivity. Therefore, Pd nanoparticles are introduced into 3DOM Co3O4 by expecting synergy from the combination of the morphological advantage of 3DOM architecture and the significant thermodynamic stability as well as the excellent ORR activity of palladium metal. Electrochemical characterizations have revealed that the combination demonstrates synergistically improved bifunctional electrocatalytic activity and durability. Moreover, computational simulation via density-functional-theory (DFT) verifies Pd@Co3O4(3DOM) is superior in two ways; (i) Activity-wise: the d-band center of Pd deposited on 3DOM Co3O4 was found to decrease significantly, resulting in increased electron abundance at the Fermi level, which in turn enhanced the overall electrical conductivity; (ii) Durability-wise: synergistic hybrid of Pd and 3DOM Co3O4 resulted in a significantly improved corrosion resistance, due to the much higher carbon oxidation potential and bulk-like dissolution potential of Pd nanoparticles on 3DOM Co3O4. The remarkable electrochemical activities and stabilities of Pd@3DOM-Co3O4 obtained from the half-cell testing resulted in excellent rechargeability of a prototype Zn-air battery, demonstrating the synergistic introduction of Pd into 3DOM Co3O4. In the last study, a type of metal-organic-framework (MOF) is selected as a template to synthesize MOF-based electrocatalyst possessing robust framework with multi-level porosity. Typically, MOF materials consist of metal centers linked by functional organic ligands, which gives them unique material characteristics such as high porosity and surface area, morphological and compositional flexibility, and high crystallinity. Especially, transition metal-based Prussian blue analogue (PBA) nanocubes with a chemical formula MxII[MyIII(CN)6]z▪H2O, where MII and MIII are divalent and trivalent transition metal cations, respectively, are employed as the MOF precursors due to a several material advantages such as simple precipitation synthesis, various possible compositions, and robust structure with high porosity

Download or read book Advanced Catalytic Materials written by Noreña Luis and published by BoD – Books on Demand. This book was released on 2016-02-03 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt: Todays chemical industry processes worldwide largely depend on catalytic reactions and the desirable future evolution of this industry toward more selective products, more environmentally friendly products, more energy-efficient processes, a smaller use of hazardous reagents, and a better use of raw materials also largely involves the development of better catalysts and, specifically, purposely designed catalytic materials. The careful study and development of the new-generation catalysts involve relatively large groups of specialists in universities, research centers, and industries, joining forces from different scientific and technical disciplines. This book has put together recent, state-of-the-art topics on current trends in catalytic materials and consists of 16 chapters.

Download or read book Advanced Bifunctional Electrochemical Catalysts for Metal Air Batteries written by Yan-Jie Wang and published by CRC Press. This book was released on 2018-12-14 with total page 257 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metal-air batteries (MABs) have attracted attention because of their high specific energy, low cost, and safety features. This book discusses science and technology including material selection, synthesis, characterization, and their applications in MABs. It comprehensively describes various composite bifunctional electrocatalysts, corrosion/oxidation of carbon-containing air cathode catalysts, and how improvements can be achieved in the catalytic activities of oxygen reduction reaction and oxygen evolution reaction and their durability/stability. This book also analyzes, compares, and discusses composite bifunctional electrocatalysts in the applications of MABs, matching the fast information of commercial MABs in requirements. Aimed at researchers and industry professionals, this comprehensive work provides readers with an appreciation for what bifunctional composite electrocatalysts are capable of, how this field has grown in the past decades, and how bifunctional composite electrocatalysts can significantly improve the performance of MABs. It also offers suggestions for future research directions to overcome technical challenges and further facilitate research and development in this important area.

Download or read book Zinc Air Batteries written by Zongping Shao and published by John Wiley & Sons. This book was released on 2023-01-04 with total page 309 pages. Available in PDF, EPUB and Kindle. Book excerpt: Zinc–Air Batteries Authoritative and comprehensive resource covering foundational knowledge of zinc–air batteries as well as their practical applications Zinc–Air Batteries provides a comprehensive understanding of the history and development of Zn–air batteries, with a systematic overview of components, design, and device innovation, along with recent advances in the field, especially with regards to the cathode catalyst design made by cutting-edge materials, engineering processes, and technologies. In particular, design principles regarding the key components of Zn–air batteries, ranging from air cathode, to zinc anode, and to electrolyte, are emphasized. Furthermore, industrial developments of Zn–air batteries are discussed and emerging new designs of Zn–air batteries are also introduced. The authors argue that designing advanced Zn–air battery technologies is important to the realization of efficient energy storage and conversion—and, going further, eventually holds the key to a sustainable energy future and a carbon-neutral goal. Edited and contributed to by leading professionals and researchers in the field, Zinc–Air Batteries also contains information regarding: Design of oxygen reduction catalysts in primary zinc–air batteries, including precious metals, single-atoms, carbons, and transition metal oxides Design of bifunctional oxygen catalysts in rechargeable zinc–air batteries, covering specific oxygen redox reactions and catalyst candidates Design of three-dimensional air cathode in zinc–air batteries, covering loading of carbon-based and transition metal catalysts, plus design of the three-phase interface Design of electrolyte for zinc–air batteries, including liquid electrolytes (e.g., alkaline) and gel polymer electrolytes (e.g., PVA hydrogel) For students, researchers, and instructors working in battery technologies, materials science, and electrochemistry, and for industry and government representatives for decision making associated with energy and transportation, Zinc–Air Batteries summarizes the research results on Zn–air batteries and thereby helps researchers and developers to implement the technology in practice.

Download or read book Nano electrocatalyst for Oxygen Reduction Reaction written by Omar Solorza Feria and published by CRC Press. This book was released on 2024-06-21 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt: Global warming switches our reliance from fossil fuels to green, sustainable renewable energy sources. Because of its promising nature, high-efficiency nano-electrocatalysts have sparked interest in renewable energy. Hydrogen fuel cell/polymer electrolyte membrane (PEM) vehicles are the most environmentally conscious electromobility vehicles, with a high energy density and quick refuelling technology, prompting the auto industry to launch a variety of PEM fuel cell vehicles around the world. Oxygen reduction reaction (ORR) primary research interests include fuel cells and metal-air batteries. The sluggish kinetic reaction of ORR, which is responsible for the rate-limiting reaction at the PEM fuel cell cathodic system, further decreases energy efficiency. Optimising ORR for market expansion with cost-effective and efficient nano-electrocatalysts, on the other hand, remains a challenge. The book covers fundamental ORR reaction kinetics theories, tools, and techniques. It also explains the nano electrocatalysts for ORR made of noble, non-noble, and nanocarbon materials. Finally, the book explores the applications of PEM fuel cells and metal-air batteries.

Download or read book Novel Non Precious Metal Electrocatalysts for Oxygen Electrode Reactions written by Hui Yang and published by MDPI. This book was released on 2019-11-01 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research on alternative energy harvesting technologies, conversion and storage systems with high efficiency, cost-effective and environmentally friendly systems, such as fuel cells, rechargeable metal-air batteries, unitized regenerative cells, and water electrolyzers has been stimulated by the global demand on energy. The conversion between oxygen and water plays a key step in the development of oxygen electrodes: oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), processes activated mostly by precious metals, like platinum. Their scarcity, their prohibitive cost, and declining activity greatly hamper large-scale applications. This issue reports on novel non-precious metal electrocatalysts based on the innovative design in chemical compositions, structure, and morphology, and supports for the oxygen reaction.

Download or read book Transition Metal Oxides Anchored Onto Heteroatom Doped Carbon Nanotubes as Efficient Bifunctional Catalysts for Rechargeable Zinc air Batteries written by Alexandra McDougall and published by . This book was released on 2021 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is well known that renewable energy, e.g., wind and solar power, are intermittent energy sources. This means that energy storage devices are needed to store the energy for when it is needed. Currently Li-ion batteries are used as these energy storage devices, not only for alternative energy plants but in vehicles and electronics. There are several drawbacks with using Li-ion batteries, such as low safety, harmful Li mining practices, and high material costs. Rechargeable zinc-air batteries (ZABs) have gained a lot of traction recently due to their low cost, high safety, low environmental impact, and high theoretical energy density. However, a major obstacle is the sluggish oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) at the air electrode, which have hindered practical applications of ZABs. Precious metal catalysts have been applied to help mitigate the slow reaction kinetics; however, these are expensive and complicate manufacturing practices since two different precious metals are needed to achieve a bifunctional catalyst. Therefore, a low-cost bifunctional catalyst is needed to improve the slow reaction kinetics at the air electrode. This work focuses on further investigating a previously developed impregnation technique for air electrode preparation using an array of transition metal (Zn, Ni, Mn, and Co) oxide combinations. Various electrochemical and microstructural characterization techniques, e.g., linear sweep voltammetry, electrochemical impedance spectroscopy, electron microscopy, and energy dispersive X-ray spectroscopy, are used to examine each sample. The first study involved fabricating several catalysts by decorating nitrogen doped carbon nanotubes (N-CNTs) with either tri-metallic (Ni-Mn-Co) or tetra-metallic (Zn-Ni-Mn-Co) oxides, through a simple impregnation method into carbon-based, gas diffusion layers (GDL). Metal oxide compositions were selected based on previous results, preliminary electrochemical testing, and statistical design of experiments (DOE). Microstructural characterization was done using electron microscopy and X-ray photoelectron spectroscopy (XPS), and determined that the oxides fabricated were spinel oxides. Samples were electrochemically tested and the best candidates were subjected to full cell testing and bifunctional cycling for 200 charge/discharge cycles at 10 mA/cm2. The overall bifunctional efficiency, after cycling, of the best NiMnCoOx/N-CNT and ZnNiMnCoOx/N-CNT catalysts was 53.3% and 56.4%, respectively; both outperformed Pt-Ru/C in both overall bifunctional efficiency (38%) and cycling stability. The maximum power density of one of the tetra-metallic oxides exceeded that of Pt-Ru/C (110 mW/cm2) at 134 mW/cm2. The addition of Zn with Ni-Mn-Co oxide particles showed improved cycling stability and overall bifunctional efficiency. The second study investigated the effect of co-doping of carbon nanotubes with nitrogen and sulfur (N,S-CNTs), combined with tri-metallic and tetra-metallic oxides, on the ORR and OER reaction kinetics at the air electrode. The best tri-metallic (Ni-Mn-Co) oxide and tetra-metallic (Zn-Ni-Mn-Co) oxide from the first study were used in this investigation. Microstructural characterization analysis revealed that the Co and Mn valences increased for the Ni-Mn-Co and Zn-Ni-Mn-Co oxides, respectively. Electrochemical testing revealed that the Ni-Mn-Co oxide was comparable to the Pt-Ru/C catalyst with a power density of ~95 mW/cm2 and Zn-Ni-Mn-Co oxide was comparable to the Pt-Ru/C catalyst with an efficiency of 56.0% at 20 mA/cm2. The addition of sulfur to the N-CNTs positively impacted the Ni-Mn-Co oxide, leading to a round trip bifunctional cycling efficiency of 55.1% for 200 charge-discharge cycles at 10 mA/cm2. The impact of sulfur did not have a positive impact on the Zn-Ni-Mn-Co oxide; the LSV results were significantly worse than the equivalent oxide on N-CNTs and the full cell testing was comparable to the N-CNT oxide. Both tri-metallic and tetra-metallic oxides outperformed Pt-Ru/C during bifunctional cycling.

Download or read book Nano Technology for Battery Recycling Remanufacturing and Reusing written by Siamak Farhad and published by Elsevier. This book was released on 2022-04-28 with total page 522 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanotechnology for Battery Recycling, Remanufacturing, and Reusing explores how nanotechnology is currently being used in battery recycling, remanufacturing and reusing technologies to make them economically and environmentally feasible. The book shows how nanotechnology can be used to enhance and improve battery recycling, remanufacturing and reusing technologies, covering the fundamentals of battery recycling, remanufacturing and reusing technologies, the role of nanotechnology, the separation, regeneration and reuse of nanomaterials from battery waste, nano-enabled approaches for battery recycling, and nano-enabled approaches for battery remanufacturing and reusing. This book will help researchers and engineers to better understand the role of nanotechnology in the field of battery recycling, remanufacturing and reusing. It will be an important reference source for materials scientists and engineers who would like to learn more about how nanotechnology is being used to create new battery recycling processes. Outlines practical and cost-efficient processes for recycling and reusing batteries Highlights the different types of nanomaterials used in battery recycling processes Assesses major challenges with integrating nanotechnology into battery manufacturing processes on an industrial scale

Download or read book Electrochemical Oxygen Reduction written by Pei Kang Shen and published by Springer Nature. This book was released on 2021-01-16 with total page 259 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book discusses systematically the theoretical research and the applications of electrochemical oxygen reduction. Oxygen reduction reaction is a common issue in electrochemistry, but is also an important process involved in the field of energy, cryogenic fuel cells, metal–air cells, oxygen sensors and hydrogen peroxide preparation. This book is divided into 6 chapters; it starts with a description of dynamic mechanisms, followed by a detailed introduction on the related experimental methods and related catalyst preparation technology. By providing the basic methods and testing techniques, and by demonstrating their applications, it helps readers gain a better understanding of oxygen reduction reactions, making it a valuable resource for the industrialization of scientific research achievements. Accordingly, the book appeals to a broad readership, particularly graduate students, those working at universities and research organizations, and industrial researchers.

Download or read book Non precious Cathode Electrocatalytic Materials for Zinc air Battery written by Baejung Kim and published by . This book was released on 2013 with total page 81 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the past decade, rechargeable batteries attracted the attention from the researchers in search for renewable and sustainable energy sources. Up to date, lithium-ion battery is the most commercialized and has been supplying power to electronic devices and hybrid and electric vehicles. Lithium-ion battery, however, does not satisfy the expectations of ever-increasing energy and power density, which of their limits owes to its intercalation chemistry and the safety.1-2 Therefore, metal-air battery drew much attention as an alternative for its high energy density and a simple cell configuration.1 There are several different types of metal-air batteries that convey different viable reaction mechanisms depending on the anode metals; such as Li, Al, Ca, Cd, and Zn. Redox reactions take place in a metal-air cell regardless of the anode metal; oxidation reaction at the anode and reduction reaction at the air electrode. Between the two reaction, the oxygen reduction reaction (ORR) at the air electrode is the relatively the limiting factor within the overall cell reactions. The sluggish ORR kinetics greatly affects the performance of the battery system in terms of power output, efficiency, and durability. Therefore, researchers have put tremendous efforts in developing highly efficient metal air batteries and fuel cells, especially for high capacity applications such as electric vehicles. Currently, the catalyst with platinum nanoparticles supported on carbon material (Pt-C) is considered to exhibit the best ORR activities. Despite of the admirable electrocatalytic performance, Pt-C suffers from its lack of practicality in commercialization due to their prohibitively high cost and scarcity as of being a precious metal. Thus, there is increasing demand for replacing Pt with more abundant metals due economic feasibility and sustainability of this noble metal.3-5 Two different attitudes are taken for solution. The first approach is by optimizing the platinum loading in the formulation, or the alternatively the platinum can be replaced with non-precious materials. The purpose of this work is to discover and synthesize alternative catalysts for metal-air battery applications through optimized method without addition of precious metals. Different non-precious metals are investigated as the replacement of the precious metal including transition metal alloys, transition metal or mixed metal oxides, and chalcogenides. These types of metals, alone, still exhibits unsatisfying, yet worse, kinetics in comparison to the precious metals. Nitrogen-doped carbon material is a recently well studied carbon based material that exhibits great potential towards the cathodic reaction.6 Nitrogen-doped carbon materials are found to exhibit higher catalytic activity compared to the mentioned types of metals for its improved conductivity. Benefits of the carbon based materials are in its abundance and minimal environmental footprints. However, the degradation of these materials has demonstrated loss of catalytic activity through destruction of active sites containing the transition metal centre, ultimately causing infeasible stability. To compensate for these drawbacks and other limits of the nitrogen-doped carbon based catalysts, nitrogen-doped carbon nanotubes (NCNT) are also investigated in the series of study. The first investigation focuses on a development of a simple method to thermally synthesize a non-precious metal based nitrogen-doped graphene (NG) electrocatalyst using exfoliated graphene (Ex-G) and urea with varying amounts of iron (Fe) precursor. The morphology and structural features of the synthesized electrocatalyst (Fe-NG) were characterized by SEM and TEM, revealing the existence of graphitic nanoshells that potentially contribute to the ORR activity by providing a higher degree of edge plane exposure. The surface elemental composition of the catalyst was analyzed through XPS, which showed high content of a total N species (~8 at.%) indicative of the effective N-doping, present mostly in the form of pyridinic nitrogen groups. The oxygen reduction reaction (ORR) performance of the catalyst was evaluated by rotating disk electrode voltammetry in alkaline electrolyte and in a zinc-air battery cell. Fe-NG demonstrated high onset and half-wave potentials of -0.023 V (vs. SCE) and -0.110 V (vs. SCE), respectively. This excellent ORR activity is translated into practical zinc-air battery performance capabilities approaching that of commercial platinum based catalyst. Another approach was made in the carbon materials to further improve the cost of the electrode. Popular carbon allotropes, CNT and graphene, are combined as a composite (GC) and heteroatoms, nitrogen and sulfur, are introduced in order to improve the charge distribution of the graphitic network. Dopants were doped through two step processes; nitrogen dopant was introduced into the graphitic framework followed by the sulfur dopant. The coexistence of the two heteroatoms as dopants demonstrated outstanding ORR performance to those of reported as metal free catalysts. Furthermore, effects of temperature were investigated through comparing ORR performances of the catalysts synthesized in two different temperatures (500 ??? and 900 ???) during the N-doping process (consistent temperature was used for S-doping). Through XPS analysis of the surface chemistry of catalysts produced with high temperature during the N-doping step showed absence of N-species after the subsequent S-doping process (GC-NHS). Thus, the synergetic effects of the two heteroatoms were not revealed during the half-cell testing. Meanwhile, the two heteroatoms were verified in the catalyst synthesized though using low temperature during the N-doping process followed by the S-doping step (GC-NLS). Consequently, ORR activity of the resulting material demonstrated promising onset and half-wave potentials of -0.117 V (vs. SCE) and -0.193 V (vs. SCE). In combination of these investigations, this document introduces thorough study of novel materials and their performance in its application as ORR catalyst in metal air batteries. Moreover, this report provides detailed fundamental insights of carbon allotropes, and their properties as potential elecrocatalysts and essential concepts in electrochemistry that lies behind zinc-air batteries. The outstanding performances of carbon based electrocatalyst are reviewed and used as the guides for further direction in the development of metal-air batteries as a promising sustainable energy resource in the future.

Download or read book Development of Manganese Oxide Based Catalysts for the Oxygen Reduction and Oxygen Evolution Reactions written by Yelena Gorlin and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Development of active catalytic materials for the oxygen reduction reaction (ORR, O2 + 4H+ + 4e- 2!2H2O) and the oxygen evolution reaction (OER, 2H2O 2!O2 + 4H+ + 4e- ) is one of the major challenges in energy conversion and storage technologies such as fuel cells, metal-air batteries, electrolysis cells, and solar fuel synthesis. The majority of industrially relevant active materials are precious metals and metal oxides, whose high cost and scarcity limits the widespread adoption of these important technologies. Manganese oxides (MnOx) catalysts are an interesting alternative to the precious metal based electrodes under alkaline conditions due to their abundance, low cost, and a demonstrated ability to catalyze both the ORR and the OER at high pH values. To accelerate the development of MnOx catalysts with improved activities for the ORR and the OER, it is important to increase understanding of the surface properties at the ORR and the OER relevant potentials. Spectroscopy techniques, including x-ray photoelectron spectroscopy (XPS) and x-ray absorption spectroscopy (XAS), are among the possible methods to monitor surface chemistry of catalytic materials. Both XPS and XAS can offer information on the electronic structure of the surface, while XAS can also probe the short-range order of the catalysts. This dissertation focuses on development of MnOx catalysts for the ORR and the OER and uses ex-situ XPS, ex-situ Mn L-edge XAS, and in-situ Mn K-edge XAS to correlate measured catalytic activity to the surface oxidation state of Mn.

Download or read book Metal Oxide Based Nanostructured Electrocatalysts for Fuel Cells Electrolyzers and Metal Air Batteries written by Teko Napporn and published by Elsevier. This book was released on 2021-01-30 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metal Oxide-Based Nanostructured Electrocatalysts for Fuel Cells, Electrolyzers, and Metal-Air Batteries is a comprehensive book summarizing the recent overview of these new materials developed to date. The book is motivated by research that focuses on the reduction of noble metal content in catalysts to reduce the cost associated to the entire system. Metal oxides gained significant interest in heterogeneous catalysis for basic research and industrial deployment. Metal Oxide-Based Nanostructured Electrocatalysts for Fuel Cells, Electrolyzers, and Metal-Air Batteries puts these opportunities and challenges into a broad context, discusses the recent researches and technological advances, and finally provides several pathways and guidelines that could inspire the development of ground-breaking electrochemical devices for energy production or storage. Its primary focus is how materials development is an important approach to produce electricity for key applications such as automotive and industrial. The book is appropriate for those working in academia and R&D in the disciplines of materials science, chemistry, electrochemistry, and engineering. Includes key aspects of materials design to improve the performance of electrode materials for energy conversion and storage device applications Reviews emerging metal oxide materials for hydrogen production, hydrogen oxidation, oxygen reduction and oxygen evolution Discusses metal oxide electrocatalysts for water-splitting, metal-air batteries, electrolyzer, and fuel cell applications

Download or read book Metal Oxide Nanocomposites written by B. Raneesh and published by John Wiley & Sons. This book was released on 2021-02-17 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metal Oxide Nanocomposites: Synthesis and Applications summarizes many of the recent research accomplishments in the area of metal oxide-based nanocomposites. This book focussing on the following topics: Nanocomposites preparation and characterization of metal oxide nanocomposites; synthesis of core/shell metal oxide nanocomposites; multilayer thin films; sequential assembly of nanocomposite materials; semiconducting polymer metal oxide nanocomposites; graphene-based metal and metal oxide nanocomposites; carbon nanotube–metal–oxide nanocomposites; silicon mixed oxide nanocomposites; gas semiconducting sensors based on metal oxide nanocomposites; metal ]organic framework nanocomposite for hydrogen production and nanocomposites application towards photovoltaic and photocatalytic.

Download or read book Carbon Nanomaterials Based on Graphene Nanosheets written by Ling Bing Kong and published by CRC Press. This book was released on 2017-03-27 with total page 611 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the discovery of graphene, it has become one of the most widely and extensively studied materials. This book aims to summarize the progress in synthesis, processing, characterization and applications of a special group of nanocarbon materials derived from graphene or graphene related derivatives by using various strategies in different forms. More specifically, three forms of macrosized materials are presented, i.e., one-dimension or 1D (fibers, wires, yarns, streads, etc.), two-dimension or 2D (films, membranes, papers, sheets, etc.) and three-dimension or 3D (bulk, hydrogels, aerogels, foams, sponges, etc.). Seven chapters are included with the first chapter serving to introduce the concept, definition, and nomenclature of graphene, graphene oxide and their derivatives. The main topics are covered in Chapters 2‒7. Although they have coherent connections, each chapter of them is designed such that they can be studied independently. The target readers of this book include undergraduate students, postgraduate students, researchers, designers, engineers, professors, and program/project managers from the fields of materials science and engineering, applied physics, chemical engineering, biomaterials, materials manufacturing and design, institutes, and research founding agencies.

Download or read book Synthesis and Characterization of Nano Structured Electrocatalysts for Oxygen Reduction Reaction in Fuel Cells written by Thomas Jefferson Cochell and published by . This book was released on 2013 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proton exchange membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs) are two types of low-temperature fuel cells (LTFCs) that operate at temperatures less than 100 °C and are appealing for portable, transportation, and stationary applications. However, commercialization has been hampered by several problems such as cost, efficiency, and durability. New electrocatalysts must be developed that have higher oxygen reduction reaction (ORR) activity, lower precious metal loadings, and improved durability to become commercially viable. This dissertation investigates the development and use of new electrocatalysts for the ORR. Core-shell (shell@core) Pt@Pd[subscript x]Cu[subscript y]/C electrocatalysts, with a range of initial compositions, were synthesized to result in a Pt-rich shell atop a Pd[subscript x]C[subscript y]-rich core. The interaction between core and shell resulted in a delay in the onset of Pt-OH formation, accounting in a 3.5-fold increase in Pt-mass activity compared to Pt/C. The methanol tolerance of the core-shell Pt@PdCu5/C was found to decrease with increasing Pt-shell coverage due to the negative potential shift in the CO oxidation peak. It was discovered that Cu leached out from the cathode has a detrimental effect on membrane-electrode assembly performance. A spray-assisted impregnation method was developed to reduce particle size and increase dispersion on the support in a consistent manner for a Pd88W12/C electrocatalyst. The spray-assisted method resulted in decreased particle size, improved dispersion and more uniform drying compared to a conventional method. These differences resulted in greater performance during operation of a single DMFC and PEMFC. Additionally, Pd88W12/C prepared by spray-assisted impregnation showed DMFC performance similar to Pt/C with similar particle size in the kinetic region while offering improved methanol tolerance. Pd88W12/C also showed comparable maximum power densities and activities normalized by cost in a PEMFC. Lastly, the activation of aluminum as an effective reducing agent for the wet- chemical synthesis of metallic particles by pitting corrosion was explored along with the control of particle morphology. It was found that atomic hydrogen, an intermediate, was the actual reducing agent, and a wide array of metals could be produced. The particle size and dispersion of Pd/C produced using Al was controlled using PVP and FeCl2 as stabilizers. The intermetallic Cu2Sb was similarly prepared with a 20 nm crystallite size for potential use in lithium-ion battery anodes. Lastly, it was found that the shape of Pd produced with Al as a reducing agent could be controlled to prepare 10 nm cubes enclosed by (100) facets with potentially high activity for the ORR.

Download or read book Advanced Materials for Clean Energy written by Qiang Xu and published by CRC Press. This book was released on 2015-04-06 with total page 623 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research for clean energy is booming, driven by the rapid depletion of fossil fuels and growing environmental concerns as well as the increasing growth of mobile electronic devices. Consequently, various research fields have focused on the development of high-performance materials for alternative energy technologies.Advanced Materials for Clean Ene