Author: Qiling Ying Publisher: ISBN: Category : Electrocatalysis Languages : en Pages : 204
Book Description
Catalysts play and essential role in nearly every chemical production process. Platinum supported on high surface area carbon substrates (Pt/C) is one of the promising candidates as an electrocatalyst in low temperature polymer electrolyte fuel cells. Developing the activity of the Pt/C catalyst with narrow Pt particle size distribution and good dispersion has been a concern in current research. In this study, the main objective was the development and characterization of inexpensive and effective nanophase Pt/C electrocatalysts.
Author: Liufeng Xiong Publisher: ISBN: Category : Languages : en Pages : 344
Book Description
Proton exchange membrane fuel cells (PEMFC) and direct methanol fuel cells (DMFC) are attractive power sources as they offer high conversion efficiencies with low or no pollution. However, the most commonly used platinum electrocatalyst is expensive and the world supply of Pt is limited. In addition, the slow oxygen reduction and methanol oxidation kinetics as well as the poisoning of the Pt catalyst at the cathode resulting from methanol permeation from the anode through the Nafion membrane to the cathode lead to significant performance loss. Also, the electrocatalyst utilization in the electrodes also needs to be improved to reduce the overall cost of the electrocatalysts and improve the fuel cell performance. This dissertation explores nanostructured Pt alloys with lower cost and higher catalytic activity than Pt for oxygen reduction in PEMFC to understand the effect of synthesis and structure on the catalytic activity, methanol tolerant Pt/TiOx nanocomposites for oxygen reduction in DMFC, nanostructured Pt-Ru alloys for methanol oxidation in DMFC, and improvement in the utilization of Pt by optimizing the membrane-electrode assembly (MEA) fabrication. From a systematic investigation of a series of Pt-M alloys (M = Fe, Co, Ni, and Cu), the catalytic activity of Pt-M alloys is correlated with the extent of atomic ordering. More ordered Pt alloys exhibit higher catalytic activity than disordered Pt alloys. The higher activity of the ordered Pt alloys is found to relate to various factors including the Pt-Pt distance, Pt: 5d orbital vacancy, {100} planar density and surface atomic configuration. The catalytic activity of the Pt alloys is also influenced by the synthesis method. Low temperature solution methods usually result in smaller particle size and higher surface area, while high temperature routes result in larger particle size and lower surface area but with a greater extent of alloying. Pt/TiOx/C nanocomposites exhibit higher performance than Pt for oxygen reduction in DMFC. The nanocomposites show higher electrchochemical surface area, lower charge transfer resistance, and higher methanol tolerance than Pt. Pt-Ru alloy synthesized by a reverse microemulsion method exhibits higher catalytic surface area than the commercial Pt-Ru. The higher catalytic activity is attributed to a better control of the particle size, crystallinity, and microstructure. Membrane-electrode assemblies (MEAs) fabricated by a modified thin film method exhibit much higher electrocatalyst utilization efficiency and performance than the conventional MEAs in PEMFC. Power densities of 715 and 610 mW/cm2 are obtained at a Pt loading of, respectively, 0.1 and 0.05 mg/cm2 and 90 oC. The higher electrocatalyst utilization is attributed to the thin catalyst layer and a better continuity of the membrane/catalysts layer interface compared to that in the conventional MEAs.
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: Shamik Chowdhury Publisher: Elsevier ISBN: 0128241675 Category : Technology & Engineering Languages : en Pages : 282
Book Description
In recent years, carbon nitride, a new type of two-dimensional (2D) material, has attracted great interest, in terms of fundamental scientific investigation and potential practical applications, for a range of energy and environmental technologies. This can be largely attributed to its optoelectronic and physicochemical properties, including moderate band gap, adjustable energy band configuration, tailor-made surface functionalities, low cost, metal-free nature, remarkable thermochemical stability, and environmentally benign manufacturing protocol. Nanostructured Carbon Nitrides for Sustainable Energy and Environmental Applications offers a comprehensive, authoritative, and critical account of the recent progress in the development and application of multifunctional carbon nitride materials and their hybrid heterostructures. There are two major objectives of this book: first, to provide a systematic overview of the key design principles toward the fabrication of high-performance carbon nitride–based nanostructures; and second, to provide insights into a range of clean energy technologies and environmental remediation methods that build on these nanoengineered carbon nitrides. This book serves as an important reference source for materials scientists and engineers who are interested in developing their understanding of how carbon-based nanomaterials are being used for sustainable energy and environmental applications. Helps users gain deeper insights into various aspects of carbon nitride materials from multidisciplinary perspectives Covers how to apply nanostructured carbon nitrides to tackle global energy and environmental challenges in a sustainable manner Explains the design and fabrication of carbon nitride-based materials with optimized structures, controlled morphologies, and tailored properties for practical implementation
Author: Naotoshi Nakashima Publisher: Springer ISBN: 3319929178 Category : Technology & Engineering Languages : en Pages : 564
Book Description
This book focuses on nanocarbons (carbon nanotubes, graphene, nanoporous carbon, and carbon black) and related materials for energy conversion, including fuel cells (predominately proton exchange membrane fuel cells [PEMFC]), Li-ion batteries, and supercapacitors. Written by a group of internationally recognized researchers, it offers an in-depth review of the structure, properties, and functions of nanocarbons, and summarizes recent advances in the design, fabrication and characterization of nanocarbon-based catalysts for energy applications. As such, it is an invaluable resource for graduate students, academics and industrial scientists interested in the areas of nanocarbons, energy materials for fuel cells, batteries and supercapacitors as well as materials design, and supramolecular science.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
The present state-of-art Proton Exchange Membrane Fuel Cell (PEMFC) technology is based on platinum (Pt) as a catalyst for both the fuel (anode) and air (cathode) electrodes. This catalyst is highly active but susceptible to poisoning by CO, which may be present in the H2-fuel used or may be introduced during the fuel processing. Presence of trace amount of CO and H2S in the H2-fuel poisons the anode irreversibly and decreases the performance of the PEMFCs. In an effort to reduce the Pt-loading and improve the PEMFC performance, we propose to synthesize a number of Pt-based binary, ternary, and quaternary electrocatalysts using Ru, Mo, Ir, Ni, and Co as a substitute for Pt. By fine-tuning the metal loadings and compositions of candidate electrocatalysts, we plan to minimize the cost and optimize the catalyst activity and performance in PEMFC. The feasibility of the novel electrocatalysts will be demonstrated in the proposed effort with gas phase CO and H2S concentrations typical of those found in reformed fuel gas with coal/natural gas/methanol feedstocks. During this reporting period we synthesized several tri-metallic electrocatalysts catalysts (Pt/Ru/Mo, Pt/Ru/Ir, Pt/Ru/W, Ptr/Ru/Co, and Pt/Ru/Se on Vulcan XG72 Carbon) by ultrasonication method. These catalysts were tested in MEAs for CO tolerance at 20 and 100 ppm CO concentrations. From Galvonstatic study the catalytic activity was found in the order of: Pt/Ru/Mo/C> Pt/Ru/Ir/C> Pt/Ru/W/C> Ptr/Ru/Co/C> and Pt/Ru/Se. The catalysts performed very well at 20 ppm CO but at 100 ppm CO performance dropped significantly.
Author: Thomas Böllinghaus Publisher: Springer Science & Business Media ISBN: 3642233481 Category : Technology & Engineering Languages : en Pages : 288
Book Description
One major goal of the World Materials Research Institute Forum - WMRIF is to promote young scientists in the field of materials science and engineering. To enhance the international knowledge exchange between young postdoctoral scientists all over the world, WMRIF meanwhile regularly organizes joint workshops among the member institutes. These workshops also represent an increasingly appreciated platform to get known to each other and to build co-operations. For such workshops, various topics are selected, pointing to future perspectives and challenges in the field of Materials Science and Engineering. This time, the presentations of the workshop focused on the four subjects Challenges in conclusive, realistic and system oriented materials testing Materials challenges for water supply Materials challenges in the extraction and recovery of scarce elements and minerals Materials challenges for nuclear fission and fusion. This book comprises the peer-reviewed contributions during the 2nd International Workshop for Young Materials Scientists at BAM Federal Institute for Materials Research and Testing, Berlin, Germany. It also provides a very informative overview of recent results for all materials scientists.
Author: Jasna Jankovic Publisher: Walter de Gruyter GmbH & Co KG ISBN: 3110623609 Category : Technology & Engineering Languages : en Pages : 555
Book Description
This book is a comprehensive introduction to the rapidly developing field of modeling and characterization of PEM fuel cells. It focuses on i) fuel cell performance modeling and performance characterization applicable from single cells to stacks, ii) fundamental and advanced techniques for structural and compositional characterization of fuel cell components and iii) electrocatalyst design. Written by experts in this field, this book is an invaluable tool for graduate students and professionals.
Author: Bradley Ladewig Publisher: John Wiley & Sons ISBN: 3527330429 Category : Technology & Engineering Languages : en Pages : 272
Book Description
There are a large number of books available on fuel cells; however, the majority are on specific types of fuel cells such as solid oxide fuel cells, proton exchange membrane fuel cells, or on specific technical aspects of fuel cells, e.g., the system or stack engineering. Thus, there is a need for a book focused on materials requirements in fuel cells. Key Materials in Low-Temperature Fuel Cells is a concise source of the most important and key materials and catalysts in low-temperature fuel cells. A related book will cover key materials in high-temperature fuel cells. The two books form part of the "Materials for Sustainable Energy & Development" series. Key Materials in Low-Temperature Fuel Cells brings together world leaders and experts in this field and provides a lucid description of the materials assessment of fuel cell technologies. With an emphasis on the technical development and applications of key materials in low-temperature fuel cells, this text covers fundamental principles, advancement, challenges, and important current research themes. Topics covered include: proton exchange membrane fuel cells, direct methanol and ethanol fuel cells, microfluidic fuel cells, biofuel cells, alkaline membrane fuel cells, functionalized carbon nanotubes as catalyst supports, nanostructured Pt catalysts, non-PGM catalysts, membranes, and materials modeling. This book is an essential reference source for researchers, engineers and technicians in academia, research institutes and industry working in the fields of fuel cells, energy materials, electrochemistry and materials science and engineering.
Author: Thomas Jefferson Cochell Publisher: ISBN: Category : Languages : en Pages : 390
Book Description
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.
Author: Qiling Ying
Author: Liufeng Xiong
Author: Kenneth I. Ozoemena
Author: Shamik Chowdhury
Author: Naotoshi Nakashima
Author: 
Author: Thomas Böllinghaus
Author: Jasna Jankovic
Author: Bradley Ladewig
Author: Thomas Jefferson Cochell