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Author: Ja-Yeon Choi Publisher: ISBN: Category : Languages : en Pages : 95
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: Ja-Yeon Choi Publisher: ISBN: Category : Languages : en Pages : 95
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: Fan Li Publisher: Springer ISBN: 3662563649 Category : Technology & Engineering Languages : en Pages : 593
Book Description
The energy crisis and pollution have posed significant risks to the environment, transportation, and economy over the last century. Thus, green energy becomes one of the critical global technologies and the use of nanomaterials in these technologies is an important and active research area. This book series presents the progress and opportunities in green energy sustainability. Developments in nanoscaled electrocatalysts, solid oxide and proton exchange membrane fuel cells, lithium ion batteries, and photovoltaic techniques comprise the area of energy storage and conversion. Developments in carbon dioxide (CO2) capture and hydrogen (H2) storage using tunable structured materials are discussed. Design and characterization of new nanoscaled materials with controllable particle size, structure, shape, porosity and band gap to enhance next generation energy systems are also included. The technical topics covered in this series are metal organic frameworks, nanoparticles, nanocomposites, proton exchange membrane fuel cell catalysts, solid oxide fuel cell electrode design, trapping of carbon dioxide, and hydrogen gas storage.
Author: Inamuddin Publisher: Materials Research Forum LLC ISBN: 1644900181 Category : Technology & Engineering Languages : en Pages : 398
Book Description
Alcohol fuel cells are very attractive as power sources for mobile and portable applications. As they convert the chemical energy of fuels into electricity, much recent research is directed at developing suitable and efficient catalysts for the process. The present book focuses on pertinent types of nanomaterial-based catalysts, membranes and supports.
Author: San Ping Jiang Publisher: CRC Press ISBN: 1466512504 Category : Science Languages : en Pages : 614
Book Description
Boasting chapters written by leading international experts, Nanostructured and Advanced Materials for Fuel Cells provides an overview of the progress that has been made so far in the material and catalyst development for fuel cells. The book covers the most recent developments detailing all aspects of synthesis, characterization, and performance. It offers an overview on the principles, classifications, and types of fuels used in fuel cells, and discusses the critical properties, design, and advances made in various sealing materials. It provides an extensive review on the design, configuration, fabrication, modeling, materials, and stack performance of μ-SOFC technology, and addresses the advancement and challenges in the synthesis, characterization, and fundamental understanding of the catalytic activity of nitrogen-carbon, carbon, and noncarbon-based electro catalysts for PEM fuel cells. The authors explore the atomic layer deposition (ALD) technique, summarize the advancements in the fundamental understanding of the most successful Nafion membranes, and focus on the development of alternative and composite membranes for direct alcohol fuel cells (DAFCs). They also review current challenges and consider future development in the industry. Includes 17 chapters, 262 figures, and close to 2000 references Provides an extensive review of the carbon, nitrogen-carbon, and noncarbon-based electro catalysts for fuel cells Presents an update on the latest materials development in conventional fuel cells and emerging fuel cells This text is a single-source reference on the latest advances in the nano-structured materials and electro catalysts for fuel cells, the most efficient and emerging energy conversion technologies for the twenty-first century. It serves as a valuable resource for students, materials engineers, and researchers interested in fuel cell technology.
Author: Drew Christopher Higgins Publisher: ISBN: Category : Languages : en Pages : 177
Book Description
Polymer electrolyte fuel cells (PEFCs) are electrochemical devices that efficiently convert hydrogen and oxygen into electricity and water. Their clean point of operation emissions and fast refueling times have resulted in PEFCs being highly touted as integral components of sustainable energy infrastructures, most notably in the transportation sector. The issues associated with hydrogen production and distribution aside, the commercial viability of PEFCs is still hindered by the high cost and inadequate long term operational stability. A main contributor towards both of these issues 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 PEFC stack cost, and undergo degradation under the cathode environment that is very corrosive due to the acidic and potentiodynamic conditions. There is therefore ample room for cost reduction if reduced platinum ORR catalysts can be developed with sufficient activity and durability to meet the technical targets set for the use of PEFCs in automobiles. In this work, two classes of nanostructured catalysts are investigated. The first is high activity platinum or platinum alloy materials with the objective of surpassing the activity of conventional catalysts on a precious metal basis to achieve cost reductions. The second is non-platinum group metal (non-PGM) catalysts, that while intrinsically less active than platinum, can still provide high power output at moderate operating voltages, such as those encountered during automobile operation. These two catalyst technologies are developed and delivered with the ultimate objective of integrating them together into platinum/non-PGM hybrid electrodes to provide excellent PEFC performance with a reduced platinum dependency. In Chapter 4, titanium nitride - carbon nanotube (TiN-CNT) core-shell nanocomposites developed by a simplistic two step fabrication procedure are reported. These materials are physicochemically characterized by a variety of microscopy and spectroscopy techniques and used as platinum nanoparticle elelectrocatalyst supports (Pt/TiN-CNT) for the ORR. Through half-cell electrochemical testing in acidic electrolyte, improved ORR activity was demonstrated for Pt/TiN-CNTs compared with state of the art commercial Pt/C. The one-dimensional morphology of the TiN-CNT supports is also conducive for integration into highly porous electrode structures with excellent interconnectivity to ensure reactant access and electronic conductivity throughout the catalyst layer, respectively. The long term stability of this catalyst however remains questionable, likely due to oxidation of the titanium nitride surface that results in a thin passivating layer. It is becoming increasingly evident that corrosion of platinum nanoparticle supports is inevitable during fuel cell operation. To overcome this, a focus was then placed on the development of supportless nanostructured platinum catalyst designs. Platinum cobalt nanowires (Pt-Co-NWs) were prepared by simplistic, template free microwave-irradiation process as discussed in Chapter 5. Using cobalt as an alloying element was undertaken owing to the documented ability of this transition metal to modulate the adsorptive properties of platinum and induce increased ORR activity. The one-dimensional anisotropic nanostructure can also provide increased platinum stability owing to the reduced surface energies in comparison to zero dimensional nanoparticles. The Pt-Co-NWs displayed promising ORR activity a through half-cell testing in 0.1 M HClO4. Most notably, using harsh accelerated durability testing (ADT) that consisted of 1,000 electrochemical potential cycles from 0 to 1.5 V vs. RHE at 50 °C, the Pt-Co-NWs maintained the majority of their ORR activity, highlighting exemplary stability. While simple, the drawback of this synthesis approach is that it did not allow for nanowire diameters that were below 40 nm. This resulted in inaccessible platinum atoms within the nanowire cores, highlighting the fact that further improved ORR activity on a platinum mass basis could be achieved with reduced diameters. To accomplish this, the electrospinning approach was used to prepare PtCoNWs (please note the nomenclature distinction). Through investigations in which synthesis parameters were systematically investigated, electrospinning was found to provide a versatile platform for the synthesis of nanowires with tunable diameters and atomic compositions. PtCoNWs with a near unity stoichiometric ratio, excellent atomic distribution and an average diameter of 28 nm were evaluated for ORR activity. Over a four-fold enhancement in Pt mass-based activity at an electrode potential of 0.9 V vs RHE is obtained in comparison to pure platinum nanowires, highlighting the beneficial impact of the alloying structure. A near 7-fold specific activity increase is also observed in comparison to commercial Pt/C catalyst, along with improved electrochemically active surface area retention through repetitive (1,000) potential cycles. Electrospinning is thereby an attractive approach to prepare morphology and composition controlled PtCoNWs that could potentially one day replace conventional nanoparticle catalysts. With the development of PtCoNWs established, developing non-PGM catalysts that can be hybridized with the high activity platinum-based catalysts was required. In Chapter 7, single crystal cobalt disulfide (CoS2) octahedral nanoparticles supported on graphene/carbon nanotube composites were prepared as ORR catalysts. During the simplistic, one-pot solvothermal synthesis, the nanostructured carbon supports were also simultaneously doped with nitrogen and sulfur. Time dependent studies elucidated the growth process of the {111} facet encased octahedra that could only be prepared when carbon support materials were incorporated into the reaction mixture. The impact of carbon support on ORR activity was clear, with the graphene/carbon nanotube composite supported CoS2 octahedra (CoS2-CG) outperforming CoS2 supported on just graphene or carbon nanotubes. Additionally, CoS2-CG provided an on-set potential (0.78 V vs. RHE) and half-wave potential (0.66 V vs. RHE) that was 60 mV and 150 mV higher than the CoS2 particle agglomerates formed when no carbon support was included during catalyst preparation. By combining the synergistic properties of the graphene/carbon nanotube composite and unique shape controlled single crystal CoS2 nanoparticles, CoS2-CG comprises the highest activity non-precious metal transition metal chalcogenide reported to date, and is presented as an emerging catalyst for the ORR in fuel cells. Chapter 8 provides a summary of the conclusions of this body of work, along with strategies that can be employed to capitalize on the scientific advancements made through this thesis. The delivery of PtCoNWs and CoS2-CG that can be reliably prepared by simple techniques provides the crucial first step towards the development of platinum/non-PGM hybrid electrodes. Future projects should focus on the integration of these two catalysts into new electrode arrangements in an attempt to exploit their individual properties. Through this approach, it is hypothesized that synergistic coupling of these two catalysts can lead to PEFC systems with reduced activation losses from the PtCoNWs, along with CoS2-CG providing increased maximum power densities at lower cell voltages, all at reduced platinum contents in comparison to state of the art PEFC cathodes.
Author: Omar Solorza Feria Publisher: CRC Press ISBN: 1040043496 Category : Science Languages : en Pages : 350
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.
Author: Timothy Crowtz Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
One of the remaining challenges driving polymer electrolyte membrane hydrogen fuel cell research is the durability of the Pt oxygen reduction reaction (ORR) catalyst. Pt is inherently unstable; minute amounts (in the order of ng/cm2 are dissolved every time the fuel cell is started, goes from idle to load, or shut-down. In addition, corrosion of carbon-based materials (ubiquitous inside fuel cells) occurs during the start-up and shut-down and also contributes to the steady decline of fuel cell performance. Adding oxygen evolution reaction (OER) catalysts, of which only Ru and Ir are stable in the acidic conditions of the fuel cell, can decrease Pt loss and carbon corrosion by mitigating the degradation mechanism which occurs during the start-up and shut-down phases. There are two challenges in developing this materials solution (there are other solutions, based on hardware systems) to the fuel cell durability problem: 1) finding the right mixture of Ru and Ir, (Ru is cheaper, more active, but less stable than Ir), and 2) balancing an increase of OER activity with a loss of ORR activity due to Pt coverage by the Ru and Ir. A spread of compositions containing various amounts of Ir or Ru on 85 ug/cm2 of Pt were sputter deposited on a nanostructured thin film state-of-the art catalyst support made by 3M. The nanostructured thin film was grown by 3M on glassy carbon disks designed for a rotating disk electrode, which was used to simulate what happens to a fuel cell cathode during repeated start-up, operation, and shut-down. Experimental difficulties of glassy carbon disk corrosion were overcome with the application of high vacuum silicone grease (silicone oil and fumed silica) to the glassy carbon disk. The silicone grease did not affect the ORR activity. Ir was found to be better at protecting the ORR activity than Ru, and an Ir on Pt sputter deposition scheme was found to be better than a Ir intermixed with Pt scheme. The second study looked for ways to visualize the OER and ORR durability of about 50 of ternary (Ir on Ru on Pt) compositions. Increasing Ir loading improved the durability of both ORR and OER activity. Various Ru loadings provided little benefit except when combined with 10 ug/cm2 Ir. There was a large amount of scatter in the data. In particular some of the experiments attained a stable ORR activity, something which should not be possible given the nature of electrochemical Pt dissolution. Further work on identifying the source of these problems is needed before another catalyst screening study is done.
Author: Shangfeng Du Publisher: Academic Press ISBN: 0128111135 Category : Technology & Engineering Languages : en Pages : 97
Book Description
One-dimensional Nanostructures for PEM Fuel Cell Applications provides a review of the progress made in 1D catalysts for applications in polymer electrolyte fuel cells. It highlights the improved understanding of catalytic mechanisms on 1D nanostructures and the new approaches developed for practical applications, also including a critical perspective on current research limits. The book serves as a reference for the design and development of a new generation of catalysts to assist in the realization of successful commercial use that have the potential to decarbonize the domestic heat and transport sectors. In addition, a further commercialization of this technology requires advanced catalysts to address major obstacles faced by the commonly used Pt/C nanoparticles. The unique structure of one-dimensional nanostructures give them advantages to overcome some drawbacks of Pt/C nanoparticles as a new type of excellent catalysts for fuel cell reactions. In recent years, great efforts have been devoted in this area, and much progress has been achieved. Provides a review of 1D catalysts for applications in polymer electrolyte fuel cells Presents an ideal reference for the design and development of a new generation of catalysts to assist in the realization of successful commercial use Highlights the progress made in recent years in this emerging field
Author: Kenneth I. Ozoemena Publisher: Springer ISBN: 3319299301 Category : Science Languages : en Pages : 583
Book Description
Global experts provide an authoritative source of information on the use of electrochemical fuel cells, and in particular discuss the use of nanomaterials to enhance the performance of existing energy systems. The book covers the state of the art in the design, preparation, and engineering of nanoscale functional materials as effective catalysts for fuel cell chemistry, highlights recent progress in electrocatalysis at both fuel cell anode and cathode, and details perspectives and challenges in future research.
Author: Ja-Yeon Choi
Author: Ja-Yeon Choi
Author: Fan Li
Author: Inamuddin
Author: San Ping Jiang
Author: Drew Christopher Higgins
Author: Omar Solorza Feria
Author: Timothy Crowtz
Author: Shangfeng Du
Author: Kenneth I. Ozoemena
Author: Michael Bron