Advanced Non-precious Metal Catalyst for Oxygen Reduction Reaction in Polymer Electrolyte Membrane Fuel Cells PDF Download

Author: Gaopeng Jiang
Publisher:
ISBN:
Category : Electrochemistry
Languages : en
Pages : 148

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Book Description
To address the global energy and environmental challenges, the polymer electrolyte membrane fuel cell (PEMFC) is proposed and developed as one of the most promising power source candidates for various applications including electric vehicles, stationary power stations and portable devices due to its high efficiency and low emissions. However, the intrinsically sluggish reaction at the cathode, namely the oxygen reduction reaction (ORR), hinders the large-scale commercialization of the PEMFC as expensive and scarce platinum-based catalysts are used to accelerate this reaction. In order to reduce the cost of PEMFC, non-precious metal catalyst (NPMC) towards ORR has been developed and already brought itself from a pure scientific curiosity to a practically viable option for some commercial applications. In this work, two classes of low-cost NPMCs are investigated. One class is composed of high temperature treated transition metal-nitrogen-carbon M-N-C (M=Fe, Co) complex catalyst, especially iron-nitrogen-carbon complex (Fe-N-C) catalyst. These materials can demonstrate decent ORR activity and durability and provide high power output at moderate operating voltages. The other class with an even lower cost is the metal-free catalyst, which omits the metal content from M-N-C catalysts completely. This type of catalyst demonstrates excellent durability, especially in the presence of species that can cause contamination (e.g. carbon monoxide) or species that can cross-over (e.g. methanol). These two classes of NPMCs are developed and delivered with the ultimate objective of achieving a significant cost reduction in PEMFC while maintaining excellent PEMFC performance and durability. Herein, the research in this thesis starts with novel N, S-co-doped Fe-N-C catalysts to meet the objective of obtaining a highly economical and efficient NPMC. The catalyst is fabricated via pyrolyzing the composite of in-situ polymerized novel N, S-co-containing precursor, polyrhodanine (PRh) onto the acid-treated carbon black via the initiation of FeCl3. The N, S-co-doped Fe-N-C catalyst is obtained after two heat-treatment steps with one acid-leaching step in between. The catalyst demonstrates excellent ORR activity, bearing a half-wave potential of 0.77 V vs RHE in the acidic electrolyte. It also shows an excellent H2-air PEMFC performance, ranking the obtained peak power density (386 mW cm-2 at 0.46 V) among the best reported NMPC catalyst in H2-air PEMFC in the world. The N, S-co-doped Fe-N-C catalyst tends to catalyze the oxygen reduction via four electron pathway according to its number of transferred electrons (>3.94) and low peroxide yield (

Author: Pouyan Zamani
Publisher:
ISBN:
Category : Carbon
Languages : en
Pages : 136

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Book Description
Polymer electrolyte membrane fuel cells (PEMFCs) are electrochemical devices that efficiently convert hydrogen and oxygen into electricity and water. Their clean point of operation emissions and continuous operation have resulted in PEMFCs being highly touted as integral components of sustainable energy infrastructures, most notably in the transportation sector as a green alternative to the internal combustion engine. The issues associated with hydrogen production and distribution aside, the commercial viability of PEMFCs into the auto- motive sector is hindered by their high cost and inadequate long-term operational stability. The main factor behind both of these problems is the platinum-based electrocatalysts used at the cathode to facilitate the inherently sluggish oxygen reduction reaction (ORR). These expensive precious metal catalysts comprise almost half of the overall PEMFC stack cost and tend to degrade in the cathode environment that is very corrosive due to the acidic and potentiodynamic conditions. The current cost targets for PEMFCs are unattainable unless the extensive reliance on this precious metal is alleviated. The cost reduction can ultimately be accomplished by developing alternative cathode catalysts for the ORR. Research on new platinum catalyst supports or nanostructured platinum alloys to increase ORR activity on a precious metal mass basis have been largely successful. This approach is not ideal, however, due to the volatile pricing and geopolitical instabilities that can likely affect the supply of platinum. For these reasons, the development of entirely non-precious metal catalysts (NPMCs) for the ORR is highly desirable. This is the objective of this thesis, as will be presented in the following sections.

Author: Jarrid A. Wittkopf
Publisher:
ISBN: 9780355251920
Category :
Languages : en
Pages : 106

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Book Description
Polymer electrolyte membrane fuel cells include proton exchange membrane fuel cells (PEMFCs) and hydroxide exchange membrane fuel cells (HEMFCs). PEMFCs use a proton conducting electrolyte, generating an acidic environment, while HEMFCs employ a hydroxide conducting electrolyte, providing a basic environment. For both types of fuel cells, the oxygen reduction reaction (ORR) at the cathode is sluggish and controls the fuel cell performance. Therefore, this thesis focuses on improving ORR catalyst activity and durability. ☐ PEMFCs, the more mature technology, have been commercially implemented in fuel cell cars like the Toyota Mirai and Honda Clarity. However, PEMFCs are expensive because they require a large amount of platinum (Pt) catalyst to overcome the ORR overpotential and the rapid catalyst degradation caused by the acidic operating environment. Current PEMFCs use Pt nanoparticles supported on amorphous carbon black as ORR catalysts. These catalysts have activity and durability concerns resulting from both the Pt nanoparticles and the amorphous carbon support. Strategies to improve catalyst activity and durability include generating a support-less catalyst, increasing the durability of the catalyst support, and switching to a basic environment. ☐ A transition to unsupported catalysts with an extended surface structure improves specific activity and durability and in turn, the cost-effectiveness of the entire fuel cell. Pt-coated copper nanowires (Pt/CuNW) exemplify these desirable catalytic traits. Improving this platform, post-synthetic processing is used to further enhance the ORR performance of the Pt/CuNW catalyst. Specifically, annealing followed by electrochemical dealloying increases activity by introducing geometric lattice tuning through Cu alloying. The resultant bimetallic PtCu-coated copper nanowire (PtCu/CuNW) catalyst yields ORR specific and mass activities of 2.65 mA cmPt-2 and 1.24 A mgPt-1, surpassing the respective DOE targets (SA and MA) of 0.72 mA cmPt-2 and 0.44 A mgPt-1. PtCu/CuNWs demonstrate enhanced durability over Pt nanoparticle catalysts by maintaining 64.1 % of its active surface area after undergoing 30,000 cycles of a potential cycling accelerated durability test (0.6 - 1.1 vs RHE). Post durability PtCu/CuNWs outperformed the DOE targets with a SA and MA of 1.50 mA cmPt-2 and 0.477 A mgPt-1 ☐ Alternately, increasing catalyst support durability through the introduction of a more durable carbon support has also been accomplished. Highly graphitic and cost-effective Cup-stacked carbon nanofiber supports have the potential to address the support durability concerns. Pt supported on carbon black (Vulcan XC-72) and cup-stacked carbon nanofibers as well as each carbon support alone underwent a high potential (1.4 V vs RHE) accelerated durability test in acidic and basic environments using rotating disk electrode techniques. It was shown that in all environments the cup-stacked carbon nanofiber support demonstrated higher durability and the catalysts tested in the basic environment had better overall stability compared to their acidic counterpart. ☐ HEMFCs have the potential for incorporating a wide variety of non-precious metal catalysts and promise to dramatically lower the fuel cell cost. One commercially available non-precious metal catalyst is Acta 4020. This carbon-based catalyst, containing 3.5 wt. % transition metals, when compared to state-of-the-art Pt/C catalysts shows comparable ORR performance and superior durability while exposed to a potential cycling (0.6 – 1.1 V vs RHE) accelerated durability test. Fuel cell testing also demonstrated the feasibility of incorporating this catalyst into the cathode electrode of a HEMFC.

Author: Zhongwei Chen
Publisher: John Wiley & Sons
ISBN: 3527664920
Category : Technology & Engineering
Languages : en
Pages : 448

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Book Description
Written and edited by top fuel cell catalyst scientists and engineers from both industry and academia, this is the first book to provide a complete overview of this hot topic. It covers the synthesis, characterization, activity validation and modeling of different non-noble metal electrocatalysts, as well as their integration into fuel cells and their performance validation, while also discussing those factors that will drive fuel cell commercialization. With its well-structured approach, this is a must-have for researchers working on the topic, and an equally valuable companion for newcomers to the field.

Author: Francisco Javier Rodríguez-Varela
Publisher: Springer
ISBN: 3319990195
Category : Science
Languages : en
Pages : 302

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Book Description
This book introduces the reader to the state of the art in nanostructured anode and cathode electrocatalysts for low-temperature acid and alkaline fuel cells. It explores the electrocatalysis of anode (oxidation of organic molecules) and cathode (oxygen reduction) reactions. It also offers insights into metal-carbon interactions, correlating them with the catalytic activity of the electrochemical reactions. The book explores the electrocatalytic behaviour of materials based on noble metals and their alloys, as well as metal-metal oxides and metal-free nanostructures. It also discusses the surface and structural modification of carbon supports to enhance the catalytic activity of electrocatalysts for fuel-cell reactions.

Author: Minhua Shao
Publisher: Springer Science & Business Media
ISBN: 1447149114
Category : Technology & Engineering
Languages : en
Pages : 748

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Book Description
Fuel cells are one of the most promising clean energy conversion devices that can solve the environmental and energy problems in our society. However, the high platinum loading of fuel cells - and thus their high cost - prevents their commercialization. Non- or low- platinum electrocatalysts are needed to lower the fuel cell cost. Electrocatalysis in Fuel Cells: A Non and Low Platinum Approach is a comprehensive book summarizing recent advances of electrocatalysis in oxygen reduction and alcohol oxidation, with a particular focus on non- and low-Pt electrocatalysts. All twenty four chapters were written by worldwide experts in their fields. The fundamentals and applications of novel electrocatalysts are discussed thoroughly in the book. The book is geared toward researchers in the field, postgraduate students and lecturers, and scientists and engineers at fuel cell and automotive companies. It can even be a reference book for those who are interested in this area.

Author: Melissa Ellen Kreider
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Book Description
Eliminating greenhouse gas emissions to mitigate the effects of climate change is a global imperative. To achieve this goal, the world's dependence on fossil fuels must be ended and renewable energy technologies must be developed and deployed on a massive scale. The electrocatalytic oxygen reduction reaction (ORR) is an important limiting step in several promising technologies, including fuel cells, metal-air batteries, and the sustainable synthesis of hydrogen peroxide. Polymer electrolyte membrane fuel cells (PEMFCs) are a clean and efficient technology for converting chemical energy, e.g. in the form of hydrogen fuel, into electrical energy for transportation and backup power generation. The majority of the efficiency losses in a PEMFC are due to the sluggish kinetics of the ORR, requiring significant loadings of platinum-based catalysts at the cathode. The scarcity and high cost of platinum is therefore a limiting factor for the widespread development of PEMFC technologies. In this dissertation, we develop several low-cost, non-precious metal ORR catalysts for acidic and alkaline media, as well as techniques for understanding the relationship between performance and material properties. First, we investigate the performance of a thin film, carbon-free nickel nitride catalyst, finding substantial ORR activity in acidic and alkaline media. We identify significant surface oxidation with testing and air exposure. Utilizing electrochemical cycling and stability testing informed by Pourbaix diagrams, the role of surface oxidation in determining catalyst activity and stability is explored. This work demonstrates the importance of understanding material surface properties and stability. We next use a molybdenum (oxy)nitride thin film system to probe the role of structure and composition in ORR performance in acidic conditions. Using extensive materials characterization, the depth-dependent structure and composition of the films are determined, discovering the high O content in the bulk of films with a highly-defected structure. This bulk O content is found to be the strongest predictor of ORR activity. We use in situ characterization techniques to understand the material changes that occur during reaction, particularly those associated with potential-dependent catalytic behavior, finding that the catalyst surface undergoes distortion, amorphization, and O incorporation. We identify a potential window in which the intrinsic catalytic activity can be enhanced without the roughening or dissolution that lead to instability. This work demonstrates how ex situ and in situ techniques can be used to develop a rigorous understanding of a catalyst material, which can then be leveraged to optimize catalyst performance. Finally, we explore corrosion-resistant, conductive antimonates as a framework for enhancing the activity and stability of transition metal active sites. The antimonates are found to have superior intrinsic activity on a TM mass basis relative to the comparable oxides in alkaline electrolyte. Strategies for improving catalyst performance including electrode engineering and doping are investigated. Validating a theoretical prediction, a Mn-Cr antimonate solid solution is found to have enhanced mass activity compared to the pure Mn antimonate (on a TM basis). Further modifications of the antimonate framework are discussed, as well as strategies for materials discovery and development. In summary, this thesis addresses the challenge of PEMFC catalyst cost and performance through the discovery and development of non-precious metal ORR catalysts. Utilizing thorough materials and electrochemical characterization, we aim to develop fundamental understanding of these catalysts and strategies for improving their performance. For the ORR and beyond, this work demonstrates approaches to materials discovery and development that will be needed to advance and commercialize a wide variety of renewable energy technologies.

Author: Ja-Yeon Choi
Publisher:
ISBN:
Category : Catalysts
Languages : en
Pages : 118

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Book Description
Polymer electrolyte membrane (PEM) fuel cells have been viewed as promising power source candidates for transport, stationary, and portable applications due to their high efficiency and low emissions. The platinum is the most commonly used catalyst material for the oxygen reduction reaction (ORR) at the cathode of PEM fuel cells; however, the limited abundance and high cost of platinum hinder the large-scale commercialization of fuel cells. Two approaches being widely accepted to overcome this limitation are 1) to improve Pt utilization to boost the activity while reducing the loading, or 2) to develop non-precious metal catalysts (NPMCs) with sufficient activity and stability to be used in the PEM fuel cells. Despite the ample amount of research and improvements, the activity and stability of these NPMCs must be further improved to be practical in PEMFC applications. The activity can be further enhanced by several different approaches including but not limited to: 1) use of different dopants (nitrogen, boron, sulfur, etc.) precursors, 2) use of different non-platinum group metals (Fe, Co, Mn), 3) utilizing high surface area support materials and 4) applying heat treatment in various conditions. The combination of these approaches affect the active site density and distribution, electronic structure of the active site thus affecting its kinetics and turn over frequency, electrical conductivity and stability of the catalyst in various ways. Herein, two chapters are included exploring with the above mentioned combinations to synthesize highly active and stable catalysts, followed by another chapter investigating its fuel cell performance and discussing possible causes of stability loss with a method to verify the issue with flooding of the microporous active sites. In the first study, non-precious metal oxygen reduction reaction (ORR) catalysts were prepared by pyrolyzing a carbon supported complex consisting of iron acetate coordinated with 1,2,4,5-tetracyanobenzene (TCNB) in an iron phtalocyanine-like polymer arrangement. By employing these small precusursor molecules, it is expected that more uniform and complete coverage of the carbon support material can be obtained, and by using the in situ formation and polymerization of FePc, effective iron-center segregation can be achieved. The results suggest that this type of catalyst has great potential used as a non-precious PEM fuel cell catalyst. In the second study, Co-N decorated porous graphene aerogel catalyst was synthesized as an efficient catalyst for ORR. In the preparation process, polyaniline (PANI) is introduced as a pore-forming agent to aid in the self-assemble of graphene species into a porous aerogel networks, and a nitrogen precursor to induce in situ nitrogen doping. Such highly desired structures can not only expose sufficient active sites for the ORR but also guarantee the fast mass transfer in the catalytic process, which provides significant catalytic activity with positive onset and half wave potentials, low hydrogen peroxide yield and remarkable stability in acid medium. In the last chapter, with a highly microporous catalyst made with dual nitrogen precursors (phenanthroline and polyaniline), a systematic study is performed to investigate micropore flooding in-situ before and after stability testing. The results do not support micropore flooding as being a large contributor to instability, at least for the family of NPMCs evaluated in this work. The protocol outlined here can be used by other researchers in the NPMC community to diagnose micropore flooding in their own respective catalysts. Several recommendations for future work were suggested in the last section of this work to further apply the knowledge to design a highly active, durable, and low-cost NPMCs.

Author: Ja-Yeon Choi
Publisher:
ISBN:
Category :
Languages : en
Pages : 95

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Book Description
Polymer electrolyte membrane (PEM) fuel cells have been viewed as promising power source candidates for transport, stationary, and portable applications due to their high efficiency and low emissions. The platinum is the most commonly used catalyst material for the oxygen reduction reaction (ORR) at the cathode of PEM fuel cells; however, the limited abundance and high cost of platinum hinder the large-scale commercialization of fuel cells. To overcome this limitation, it is necessary to enhance the catalyst utilization in order to improve the catalytic activity while decreasing or eliminating the use of platinum. The material on which the catalyst is supported is important for the high dispersion and narrow distribution of Pt nanoparticles as well as other non-precious metal active sites, and these characteristics are closely related to electrocatalytic activity of the catalysts. The support materials can influence the catalytic activity by interplaying with catalytic metals, and the durability of the catalyst is also greatly dependent on its support. A variety of support materials like carbons, oxides, carbides, and nitrides have been employed as supports materials for fuel cell catalysts, and much effort has been devoted to the synthesis of the novel carbon supports with large surface area and/or pore volume, including nanostructured carbons such as carbon nanotubes (CNTs), carbon nanofibers, and mesoporous carbon. These novel nanostructured carbon materials have achieved promising performance in terms of catalytic activity and durability. However, there is still enormous demand and potential for the catalysts to improve.

Author: Omar Solorza Feria
Publisher: CRC Press
ISBN: 1040043496
Category : Science
Languages : en
Pages : 350

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Book Description
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.