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Author: Jaroslava Lavková
Publisher:
ISBN:
Category :
Languages : en
Pages : 298
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Book Description
Present doctoral thesis is focused on investigation of novel metal-oxide anode catalyst for fuel cell application by electron microscopy and associated spectroscopies. Catalysts based on Pt-doped cerium oxide in form of thin layers prepared by simultaneous magnetron sputtering deposition on intermediate carbonaceous films grown on silicon substrate have been studied. The influence of the catalyst support composition (a-C and CNx films), deposition time of CeOx layer and other deposition parameters, as deposition rate, composition of working atmosphere and Pt concentration on the morphology of Pt-CeOx layers has been investigated mainly by Transmission Electron Microscopy (TEM). The obtained results have shown that by combination of suitable preparation conditions we are able to tune the final morphology and composition of the catalysts. The composition of carbonaceous films and Pt-CeOx layers was examined by complementary spectroscopy techniques - Energy Dispersive X-ray Spectroscopy (EDX), Electron Energy Loss Spectroscopy (EELS) and X-ray Photoelectron Spectroscopy (XPS). Such prepared porous structures of Pt-CeOx are promising as anode catalytic material for real fuel cell application.
Author: Jaroslava Lavková
Publisher:
ISBN:
Category :
Languages : en
Pages : 298
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Book Description
Present doctoral thesis is focused on investigation of novel metal-oxide anode catalyst for fuel cell application by electron microscopy and associated spectroscopies. Catalysts based on Pt-doped cerium oxide in form of thin layers prepared by simultaneous magnetron sputtering deposition on intermediate carbonaceous films grown on silicon substrate have been studied. The influence of the catalyst support composition (a-C and CNx films), deposition time of CeOx layer and other deposition parameters, as deposition rate, composition of working atmosphere and Pt concentration on the morphology of Pt-CeOx layers has been investigated mainly by Transmission Electron Microscopy (TEM). The obtained results have shown that by combination of suitable preparation conditions we are able to tune the final morphology and composition of the catalysts. The composition of carbonaceous films and Pt-CeOx layers was examined by complementary spectroscopy techniques - Energy Dispersive X-ray Spectroscopy (EDX), Electron Energy Loss Spectroscopy (EELS) and X-ray Photoelectron Spectroscopy (XPS). Such prepared porous structures of Pt-CeOx are promising as anode catalytic material for real fuel cell application.
Author: Haijiang Wang
Publisher: CRC Press
ISBN: 1439839174
Category : Science
Languages : en
Pages : 366
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Book Description
PEM Fuel Cell Failure Mode Analysis presents a systematic analysis of PEM fuel cell durability and failure modes. It provides readers with a fundamental understanding of insufficient fuel cell durability, identification of failure modes and failure mechanisms of PEM fuel cells, fuel cell component degradation testing, and mitigation strategies against degradation. The first several chapters of the book examine the degradation of various fuel cell components, including degradation mechanisms, the effects of operating conditions, mitigation strategies, and testing protocols. The book then discusses the effects of different contamination sources on the degradation of fuel cell components and explores the relationship between external environment and the degradation of fuel cell components and systems. It also reviews the correlation between operational mode, such as start-up and shut-down, and the degradation of fuel cell components and systems. The last chapter explains how the design of fuel cell hardware relates to failure modes. Written by international scientists active in PEM fuel cell research, this volume is enriched with practical information on various failure modes analysis for diagnosing cell performance and identifying failure modes of degradation. This in turn helps in the development of mitigation strategies and the increasing commercialization of PEM fuel cells.
Author: Mark Dreibelbis
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
As part of collaborative efforts to develop new materials for use in polymer electrolyte membrane fuel cells, techniques for the high throughput synthesis and evaluation of thin films have been developed. These studies have revealed several multimetallic systems (both disordered alloys and ordered intermetallics) that are potential candidates for improved anode and cathode electrocatalysts. However, if those complex metallic materials are to be used as fuel cell electrocatalysts, they must be prepared as high surface area nanoparticles, typically as small as 3 to 5 nm in diameter. This dissertation describes efforts to understand intermetallic nanoparticle formation, and an example of preparing one of those promising thin film compositions as nanoparticles. Intermetallic PtPb is known to be an active anode electrocatalyst for formic acid oxidation and is much less sensitive to poisoning by CO and sulfur-containing compounds than the typical Pt catalyst. Solution-phase synthesis of this compound from organometallic precursors co-reduced via sodium naphthalide has produced nanoparticles that retain this activity, and varying reaction conditions provides insight as to how they form. Hydrocarbon adsorption is shown to be a likely inhibitor of intermetallic nanoparticle formation. Single- and double-potential step chronoamperometry methods are also used to investigate the first step of this synthesis- the rates at which the metal precursors are reduced and dissociate in solution. Under the assumptions of the electroanalytical measurements, the coreduced precursors do appear to reduce near the same rate. A promising thin film composition for oxygen reduction is palladium alloyed with tungsten and vanadium. Results are shown for the synthesis of ternary alloys near the composition Pd0.88W0.6V0.06 as nanoparticles which retain some of their oxygen reduction activity from that of the initial thin film used in the screening protocols. Powder x-ray diffraction (pXRD), electron microscopy (SEM and TEM), energy dispersive x-ray spectroscopy (EDS), and rotating disk electrode (RDE) experiments serve as the primary means of characterizing these nanoparticle catalysts.
Author: Frances M. Ross
Publisher: Cambridge University Press
ISBN: 1107116570
Category : Science
Languages : en
Pages : 529
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Book Description
2.6.2 Electrodes for Electrochemistry
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 8
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Book Description
In this study, the nanoscale morphology of highly active Pt3Ni7 nanostructured thin film fuel cell catalysts is linked with catalyst surface area and activity following catalyst pretreatments, conditioning and potential cycling. The significant role of fuel cell conditioning on the structure and composition of these extended surface catalysts is demonstrated by high resolution imaging, elemental mapping and tomography. The dissolution of Ni during fuel cell conditioning leads to highly complex, porous structures which were visualized in 3D by electron tomography. Quantification of the rendered surfaces following catalyst pretreatment, conditioning, and cycling shows the important role pore structure plays in surface area, activity, and durability.
Author: Said Salaheldeen Elnashaie
Publisher: Springer
ISBN: 9812874968
Category : Technology & Engineering
Languages : en
Pages : 285
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Book Description
The book describes the basic principles of transforming nano-technology into nano-engineering with a particular focus on chemical engineering fundamentals. This book provides vital information about differences between descriptive technology and quantitative engineering for students as well as working professionals in various fields of nanotechnology. Besides chemical engineering principles, the fundamentals of nanotechnology are also covered along with detailed explanation of several specific nanoscale processes from chemical engineering point of view. This information is presented in form of practical examples and case studies that help the engineers and researchers to integrate the processes which can meet the commercial production. It is worth mentioning here that, the main challenge in nanostructure and nanodevices production is nowadays related to the economic point of view. The uniqueness of this book is a balance between important insights into the synthetic methods of nano-structures and nanomaterials and their applications with chemical engineering rules that educates the readers about nanosclale process design, simulation, modelling and optimization. Briefly, the book takes the readers through a journey from fundamentals to frontiers of engineering of nanoscale processes and informs them about industrial perspective research challenges, opportunities and synergism in chemical Engineering and nanotechnology. Utilising this information the readers can make informed decisions on their career and business.
Author: Elliot Padgett
Publisher:
ISBN:
Category :
Languages : en
Pages : 225
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Book Description
Hydrogen fuel cells in fuel cell electric vehicles (FCEVs) are a promising technology to reduce, and eventually eliminate, carbon dioxide emissions from transportation. The Pt nanoparticles used to catalyze the fuel cell's electrochemical reactions are an important limiting factor because at present levels, the cost of the Pt catalyst will prevent widespread adoption of FCEVs. Catalysts must be developed to reduce the amount of Pt while meeting vehicle power demands even after many years of use. Strategically improving catalysts requires detailed and statistically robust characterization of their microscopic structure to understand the connections between catalyst synthesis, structure, performance, and durability. This dissertation presents the development and application of (scanning) transmission electron microscopy ((S)TEM) techniques to guide advancement of catalysts through nanostructural characterization. We develop a robust strain mapping technique for complex catalyst specimens. We deploy a new exit wave power cepstrum (EWPC) transform to nanobeam electron diffraction (NBED) patterns to enable precise, high-throughput, dose-efficient strain measurement. This approach is suitable for statistically representative measurements of many particles without special requirements such as zone-axis orientation. We apply this strain mapping technique to core-shell Pt-Co nanoparticles in combination with a continuum elastic theory model and demonstrate two mechanisms contributing to the relaxation of strain at the catalyst surface: lattice dislocations and Poisson expansion due to the spherical geometry. Comparison with electrochemical measurements suggests that the geometrical Poisson relaxation accounts for the activity of catalysts with thin shells, but catalysts with thick shells experience additional activity loss from dislocation-driven relaxation. We then turn to the larger-scale catalyst structure, investigating the impact of porous carbon support morphology, local reactant transport, and catalyst durability. Using statistical analysis of STEM images, we compare Pt and Pt-Co catalysts on porous and solid carbon supports. Comparison of 3D tomographic images and electrochemical accessibility measurements indicated that carbon pores prevent ionomer adsorption for particles embedded within them, improving the catalyst activity, while allowing proton access through condensed water. By comparing images and composition maps before and after electrochemical stability tests, we find that porous carbon supports suppress Pt particle coalescence, accounting for improved overall durability.
Author: Antonella Macagnano
Publisher: MDPI
ISBN: 3039287389
Category : Technology & Engineering
Languages : en
Pages : 386
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Book Description
Due to their unique size-dependent physicochemical properties, nanostructured thin films are used in a wide range of applications from smart coating and drug delivery to electrocatalysis and highly-sensitive sensors. Depending on the targeted application and the deposition technique, these materials have been designed and developed by tuning their atomic-molecular 2D- and/or 3D-aggregation, thickness, crystallinity, and porosity, having effects on their optical, mechanical, catalytic, and conductive properties. Several open questions remain about the impact of nanomaterial production and use on environment and health. Many efforts are currently being made not only to prevent nanotechnologies and nanomaterials from contributing to environmental pollution but also to design nanomaterials to support, control, and protect the environment. This Special Issue aims to cover the recent advances in designing nanostructured films focusing on environmental issues related to their fabrication processes (e.g., low power and low cost technologies, the use of environmentally friendly solvents), their precursors (e.g., waste-recycled, bio-based, biodegradable, and natural materials), their applications (e.g., controlled release of chemicals, mimicking of natural processes, and clean energy conversion and storage), and their use in monitoring environment pollution (e.g., sensors optically- or electrically-sensitive to pollutants)
Author:
Publisher:
ISBN:
Category : Chemistry
Languages : en
Pages : 2676
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Book Description
Author: Kevin Kendall
Publisher: Elsevier
ISBN: 0124104835
Category : Technology & Engineering
Languages : en
Pages : 522
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Book Description
High-temperature Solid Oxide Fuel Cells, Second Edition, explores the growing interest in fuel cells as a sustainable source of energy. The text brings the topic of green energy front and center, illustrating the need for new books that provide comprehensive and practical information on specific types of fuel cells and their applications. This landmark volume on solid oxide fuel cells contains contributions from experts of international repute, and provides a single source of the latest knowledge on this topic. - A single source for all the latest information on solid oxide fuel cells and their applications - Illustrates the need for new, more comprehensive books and study on the topic - Explores the growing interest in fuel cells as viable, sustainable sources of energy
