Read Books Online and Download eBooks, EPub, PDF, Mobi, Kindle, Text Full Free.
Strong Metal Support Interaction Of Pt Based Electrocatalysts With Transition Metal Oxides Nitrides Carbides For Oxygen Reduction Reaction
Download Strong Metal Support Interaction Of Pt Based Electrocatalysts With Transition Metal Oxides Nitrides Carbides For Oxygen Reduction Reaction full books in PDF, epub, and Kindle. Read online Strong Metal Support Interaction Of Pt Based Electrocatalysts With Transition Metal Oxides Nitrides Carbides For Oxygen Reduction Reaction ebook anywhere anytime directly on your device. Fast Download speed and no annoying ads. We cannot guarantee that every ebooks is available!
Book Synopsis Strong metal-support interaction of Pt-based electrocatalysts with transition metal oxides/nitrides/carbides for oxygen reduction reaction by : Min Chen
Download or read book Strong metal-support interaction of Pt-based electrocatalysts with transition metal oxides/nitrides/carbides for oxygen reduction reaction written by Min Chen and published by OAE Publishing Inc.. This book was released on 2023-06-06 with total page 31 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Development of Transition Metal Carbide and Nitride Electrocatalysts for Chemical Energy Storage and CO2 Conversion by : Brian M. Tackett
Download or read book Development of Transition Metal Carbide and Nitride Electrocatalysts for Chemical Energy Storage and CO2 Conversion written by Brian M. Tackett and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This correlated well with density functional theory (DFT) calculations of the hydrogen binding energy on the Pt/NbC surface. Potential applications of transition metal nitrides as electrocatalyst support materials were explored by synthesizing thin film nitrides of niobium and tungsten. The stability of each nitride was evaluated across broad potential-pH regimes to create a pseudo-Pourbaix diagram for each one. The films were each modified with atom-thick layers of Pt and were evaluated for HER performance in acid and alkaline electrolyte. Thin layers of Pt on WN and NbN showed Pt-like HER performance in acid and are promising candidates for high-surface area catalysts. To address the issue of high iridium (Ir) loading for the oxygen evolution reaction (OER) at the water electrolyzer anode, core-shell Ir-metal nitride particles were synthesized that contained 50% of the Ir mass loading of benchmark IrO¬2 particles. Iridium-iron nitride (Ir/Fe4N) showed increased activity on a mass-Ir basis and on a per-site basis, compared to IrO2.
Book Synopsis Rational Design of Transition Metal-Nitrogen-Carbon Electrocatalysts for Oxygen Reduction Reaction by : Zhuang Liu
Download or read book Rational Design of Transition Metal-Nitrogen-Carbon Electrocatalysts for Oxygen Reduction Reaction written by Zhuang Liu and published by . This book was released on 2018 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT OF THE DISSERTATION Rational Design of Transition Metal-Nitrogen-Carbon Electrocatalysts for Oxygen Reduction Reaction by Zhuang Liu Doctor of Philosophy in Chemical Engineering University of California, Los Angeles, 2018 Professor Yunfeng Lu, Chair The harvest and conversion of energy is of crucial importance for human civilization. Today, the fast growth in energy consumption, together with the environmental problems caused by fossil fuel usage, calls for renewable and clean energy supply, such as solar, wind, geothermal, and tidal energy. However, such energies are not consistent in both time and location, bringing energy storage on request. Intensive research has been focused on the development of electrochemical energy storage (EES) devices. Among these EES devices, hydrogen fuel cells and metal-air batteries have attracted the special attention because of their high theoretical energy densities. Yet, one major issue lies in the sluggish oxygen reduction reaction (ORR) that takes place at the cathodes. For example, the theoretical voltage of a hydrogen-oxygen fuel cell is 1.23 V (standard condition). However, the voltage output obtained under a meaningful current density is only about 0.7 V, where the voltage loss is primarily caused by the overpotential in the cathodes. Developing efficient electro-catalysts, which can lower the overpotential of ORR, is indispensable for achieving high performance devices. The state-of-the-art ORR electro-catalysts are generally based on platinum, which is limited by cost and scarcity. Developing electro-catalysts based on earth abundant metal elements is critical for large-scale application of fuel cells and metal-air batteries. Among the non-precious-metal catalysts (NPMCs) explored in recent decades, pyrolyzed iron-nitrogen-carbon (Fe-N-C) catalysts is widely regarded as the most promising candidate for replacing platinum due to their high activity. However, the traditional method for preparing Fe-N-C catalysts involves high-temperature pyrolysis of the precursors, which is a highly complex and unpredictable process. As-prepared Fe-N-C catalysts usually contain mixed chemical phases (e.g., Fe-based nanoparticles, Fe-N coordination site and various nitrogen species), as well as carbon scaffolds with random morphology. Such complexity makes it difficult to identify the active site and control the porous structure. Though progress has been made in improving their performance through delicate selection of precursors, such process is largely based on test-and-trial method, shedding little light on the understanding of the material. In this dissertation, we designed a novel "post iron decoration" synthetic strategy towards efficient Fe-N-C catalysts, which de-convolutes the growth of iron and nitrogen species, enables the rational design of the catalyst structure, and provides a series of effective model materials for active site probing. Specifically, liquid iron penta-carbonyl was used to wet the surface of mesoporous N-doped carbon spheres (NMC), whose porous structure is determined by the template used for preparation. The obtained Fe(CO)5/NMC complex was then pyrolyzed to generate the Fe/NMC catalysts. Through comparative study and thorough material characterization, we demonstrated that the pyridinic-N of NMC anchors the Fe atoms to form Fe-Nx active sites during pyrolysis, while the graphitic-N remains ORR active. The excessive Fe atoms were aggregated forming fine nanoparticles, which were subsequently oxidized forming amorphous-iron oxide/iron crystal core-shell structure. All the composing elements of Fe/NMC catalysts are uniformly distributed on the NMC scaffold, whose porous structure is shown to be not affected by Fe decoration, guaranteeing the effective exposure of active sites. The best performing Fe/NMC catalysts exhibited a high half-wave potential of 0.862 V, which is close to that of the benchmark 40% Pt/C catalyst. Such high activity is primarily attributed to the Fe-Nx active sites in the catalysts. While the surface oxidized Fe crystallites though not being the major active site, is revealed to catalyze the reduction of HO2-, the 2e ORR product, facilitating the 4e reduction of oxygen. Finally, such synthetic strategy is successfully extended to prepare other Me-N-C materials. Based on the established understanding of the active sites, we then complexed the active Fe(CO)5 molecules with a N-rich metal-organic framework (ZIF-8) to form a precursor, which was subsequently pyrolyzed to form Fe-NC catalysts. During the pyrolysis, Fe(CO)5 reacts homogeneously with the ZIF-8 scaffold, leading to the formation of uniform distribution of Fe-related active sites on the N-rich porous carbon derived from ZIF-8. The zinc atoms in the crystalline structure of ZIF-8 serves as thermo-sacrificial template, resulting in the formation of hierarchical pores that provide abundant easily accessible ORR active sites. In virtue of these advantageous features, the best performing Fe-NC catalyst exhibited a high half-wave potential of 0.91 V in rotating disk electrode experiment in 0.1 M NaOH. Furthermore, zinc-air battery constructed with Fe-NC-900-M as the cathode catalyst exhibited high open-circuit voltage (1.5 V) and a peak power density of 271 mW cm-2, which outperforms those made with 40% Pt/C catalyst (1.48 V, 1.19 V and 242 mW cm-2), and most noble-metal free ORR catalysts reported so far. Finally, such a synthetic method is economic and easily-scalable, offering possibility for further activity and durability improvement.
Book Synopsis Transition Metal Carbides and Nitrides by : Louis Toth
Download or read book Transition Metal Carbides and Nitrides written by Louis Toth and published by Elsevier. This book was released on 2014-04-11 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: Refractory Materials, Volume 7: Transition Metal Carbides and Nitrides discusses the developments in transition metal carbide and nitride research. This volume is organized into nine chapters that emphasize the mechanical and superconducting properties of these compounds. The introductory chapters deal with the general properties, preparation techniques, characterization, crystal chemistry, phase relationships, and thermodynamics of transition metal carbides and nitrides. The following chapter highlights the mechanical properties of these compounds, such as elastic and plastic deformation, fracture, strengthening mechanisms, and hardness. The discussion then shifts to specific electrical and magnetic properties, including electrical resistivity, Hall coefficient, and magnetic susceptibility. A separate chapter is devoted to carbides and nitrides as superconductors. The concluding chapters explore certain theories that explain the mechanisms of band structure and bonding in carbides and nitrides. This volume is of great value to research workers in metallurgy, ceramics, physics, chemistry, and related fields, as well as to advanced students investigating problems concerning high temperature materials or interstitial compounds.
Book Synopsis Strong Metal-support Interactions by : R. T. K. Baker
Download or read book Strong Metal-support Interactions written by R. T. K. Baker and published by . This book was released on 1986 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Role of Metal-support Interactions on the Activity of Pt and Rh Catalysts for Reforming Methane and Butane by :
Download or read book Role of Metal-support Interactions on the Activity of Pt and Rh Catalysts for Reforming Methane and Butane written by and published by . This book was released on 2002 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: For residential fuel cell systems, reforming of natural gas is one option being considered for providing the H2 necessary for the fuel cell to operate. Industrially, natural gas is reformed using Ni-based catalysts supported on an alumina substrate, which has been modified to inhibit coke formation. At Argonne National Laboratory, we have developed a new family of catalysts derived from solid oxide fuel cell technology for reforming hydrocarbon fuels to generate H2. These catalysts consist of a transition metal supported on an oxide-ion-conducting substrate, such as ceria, that has been doped with a small amount of a non-reducible element, such as gadolinium, samarium, or zirconium. Unlike alumina, the oxide-ion-conducting substrate has been shown to induce strong metal-support interactions. Metal-support interactions are known to play an important role in influencing the catalytic activity of many metals supported on oxide supports. Based on results from temperature-programmed reduction/oxidation and kinetic reaction studies, this paper discusses the role of the metal and the substrate in the metal-support interactions, and how these interactions influence the activity and the selectivity of the catalyst in reforming methane and butane to hydrogen for use in fuel cell power systems.
Book Synopsis The Influence of Non-carbon Support Materials on the Activity and Stability of the Platinum Supported Electrocatalysts by : Ying Liu
Download or read book The Influence of Non-carbon Support Materials on the Activity and Stability of the Platinum Supported Electrocatalysts written by Ying Liu and published by . This book was released on 2013 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis 3D Interface-engineered Transition Metal Oxide/carbon Hybrid Structures for Efficient Bifunctional Oxygen Electrocatalysis in Alkaline and Acidic Environments by : Simranjit Kaur Grewal
Download or read book 3D Interface-engineered Transition Metal Oxide/carbon Hybrid Structures for Efficient Bifunctional Oxygen Electrocatalysis in Alkaline and Acidic Environments written by Simranjit Kaur Grewal and published by . This book was released on 2021 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt: Use of regenerative fuel cells requires efficient bifunctionality in oxygen electrocatalysis: oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Commonly used noble metals like Pt and its alloys (Pt/Ir or Pt/Ru) are often used for their catalytic activity, selectivity and stability in harsh environments. However, Pt can degrade during operation from catalyst agglomeration and poisoning. Therefore, researchers have used non-precious transition metal oxides (TMO) including Fe3O4, MnOx and Co3O4 and/or nanocarbon structures (NC) as potential catalyst. Composite structures where TMO nanoparticles are deposited onto a NC, derived from either graphene oxide (GO) or metal-organic frameworks (MOFs), have often been used. NCs have high surface area and excellent electronic conductivity, and while many studies assert these types of composite materials exhibiting synergistic effects in oxygen electrocatalysis, efforts to elucidate the origin of the synergy is lacking. This doctoral research explores how functional groups present on the surface of NCs affect synergy (reaction route and kinetics) of these electrocatalysis. To incur catalytically active sites between the metal oxides and carbon, the NCs basal plane were functionalized using acid treatments, after which various types of TMO/NC hybrids were synthesized using either wet process or vacuum deposition techniques. The hydroxylated CeO2/graphene hybrids showed the best ORR and OER performance in both alkaline and acidic media, in terms of onset/half-wave potential, electron transfer number, and current density when compared to the performance of benchmark catalysts: Pt/C (for ORR) and IrO2 (for OER). From a series of material and electrochemical analyses, it was determined that a strong tethering of TMOs on graphene's basal plane prohibited restacking and particle-carbon interfaces dictates the performance and reaction route, as indicated in density functional theory calculations. In addition, a hybrid catalyst of TiO2 nanodots, uniformly anchored on phosphorylated carbon by atomic layer deposition (ALD), showed even better ORR and OER performance in alkaline media when compared the aforementioned CeO2/graphene hybrid. Materials characterization emphasized a strong adhesion of TMOs on MOF structures; thus providing ample surface interactions for a favorable reaction route. Therefore, an activation of catalytic sites can be realized by proper engineering of interfaces in each hybrid system.
Download or read book Nanocasting written by An-Hui Lu and published by Royal Society of Chemistry. This book was released on 2010 with total page 279 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanostructured materials with tailored properties are regarded as a fundamental element in the development of future science and technology. Research is still ongoing into the nanosized construction elements required to create functional solids. The recently developed technique, nanocasting, has great advantage over others in terms of the synthesis of special nanostructured materials by the careful choice of suitable elements and nanoengineering steps. This new book summarizes the recent developments in nanocasting, including the principles of nanocasting, syntheses of novel nanostructured materials, characterization methods, detailed synthetic recipes and further possible development in this area. The book focuses on the synthesis of porous solids from the viewpoint of methodology and introduces the science of nanocasting from fundamental principles to their use in synthesis of various materials. It starts by outlining the principles of nanocasting, requirements to the templates and precursors and the tools needed to probe matter at the nanoscale level. It describes how to synthesize nano structured porous solids with defined characteristics and finally discusses the functionalization and application of porous solids. Special attention is given to new developments in this field and future perspectives. A useful appendix covering the detailed synthetic recipes of various templates including porous silica, porous carbon and colloidal spheres is included which will be invaluable to researchers wanting to follow and reproduce nanocast materials. Topics covered in the book include: * inorganic chemistry * organic chemistry * solution chemistry * sol-gel and interface science * acid-base equilibria * electrochemistry * biochemistry * confined synthesis The book gives readers not only an overview of nanocasting technology, but also sufficient information and knowledge for those wanting to prepare various nanostructured materials without needing to search the available literature.
Book Synopsis Platinum Monolayer Electrocatalysts by : Radoslav Adzic
Download or read book Platinum Monolayer Electrocatalysts written by Radoslav Adzic and published by Springer Nature. This book was released on 2020-08-11 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes a science and technology of a new type of electrocatalysts consisting of a single atomic layer of platinum on suitable supports. This development helped overcome three major obstacles—catalysts‘ cost, activity, and stability—for a broad range of fuel cell applications. The volume begins with a short introduction to the science of electrocatalysis, covering four reactions important for energy conversion in fuel cells. A description follows of the properties of metal monolayers on electrode surfaces, and underpotential deposition of metals. The authors then describe the concept of Pt monolayer electrocatalysts and its implications and their synthesis by galvanic displacement of less-noble metal monolayers and other methods. The main part of the book presents a discussion of catalysts’ characterization and catalytic properties of Pt monolayers for the four main reactions of electrochemical energy conversion: oxygen reduction and oxidation of hydrogen, methanol and ethanol. The book concludes with a treatment of scale-up syntheses, fuel cell tests, catalysts’ stability and application prospects.
Book Synopsis Materials for Low-Temperature Fuel Cells by : Bradley Ladewig
Download or read book Materials for Low-Temperature Fuel Cells written by Bradley Ladewig and published by John Wiley & Sons. This book was released on 2015-03-09 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Oxygen Reduction Reaction Study of Transition Metal Carbide Catalysts and Their Performance in Proton Exchange Membrane Fuel Cells by : Jose Andres Cabrera Rodas
Download or read book Oxygen Reduction Reaction Study of Transition Metal Carbide Catalysts and Their Performance in Proton Exchange Membrane Fuel Cells written by Jose Andres Cabrera Rodas and published by . This book was released on 2018 with total page 35 pages. Available in PDF, EPUB and Kindle. Book excerpt: The contemporary global energetic requirements elucidate the need for alternative energy sources. This work presents a catalyst platform consisting of platinum supported on phase-pure molybdenum carbide and evaluates its implementation in fuel cell devices. Specifically, proton exchange membrane fuel cells (PEMFC), as the basis for harvesting energy more efficiently. Further, PEMFCs require electrocatalytic surface to speed up the oxygen reduction reaction (ORR) kinetics, so practical usable levels in fuel cell devices can be attained. Platinum-based catalysts are the most effective catalysts delivering high ORR activity. Unfortunately, the high cost and scarcity of Pt have limited the development of more efficient fuel cells for both stationary and portable applications. Alternatively, the catalyst platform proposed here has considerably lower Pt mass loading (less than 5%) than commercially available catalysts (20-50%), while maintaining catalytic activity and durability comparable to and superior power per Pt loading (14.32 kW/g) than commercial 20% Pt/C (6.87 kW/g).
Book Synopsis Theoretical Studies of Transition Metal Surfaces as Electrocatalysts for Oxygen Electroreduction by : Eduardo J. Lamas
Download or read book Theoretical Studies of Transition Metal Surfaces as Electrocatalysts for Oxygen Electroreduction written by Eduardo J. Lamas and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In the last few years the quest towards a hydrogen based economy has intensified interest for effective and less expensive catalysts for fuel cell applications. Due to its slow kinetics, alternative catalysts for the oxygen electroreduction reaction are actively researched. Platinum alloys with different transition metals (for example: Ni, Co and Fe) have shown improved activity over pure Pt. The design of a Pt-free catalysts is also highly desirable, and different alternatives including metalloporphyrins and Pd-based catalysts are being researched. Pd-based catalysts constitute an attractive alternative to Pt alloys in some fuel cell applications, not only because of lower costs but also because of the lower reactivity of Pt alloys towards methanol, which is important for improved methanol crossover tolerance on direct methanol fuel cells. In this work we apply density functional theory (DFT) to the study of four catalysts for oxygen electroreduction. The electronic structure of these surfaces is characterized together with their surface reconstruction properties and their interactions with oxygen electroreduction intermediates both in presence and absence of water. The energetics obtained for the intermediates is combined with entropy data from thermodynamic tables to generate free energy profiles for two representative reaction mechanisms where the cell potential is included as a variable. The study of the barriers in these profiles points to the elementary steps in the reaction mechanisms that are likely to be rate-determining. The highest barrier in the series pathway is located at the first proton and charge transfer on all four catalytic surfaces. This is in good agreement with observed rate laws for this reaction. The instability of hydrogen peroxide on all surfaces, especially compared with the relatively higher stability of other intermediates, strongly points at this intermediate as the most likely point where the oxygen bond is broken during oxygen reduction. This adds to the argument that this path might be active during oxygen electroreduction. A better understanding behind the reaction mechanism and reactivities on these representative surfaces will help to find systematic ways of improvement of currently used catalysts in the oxygen electroreduction reaction.
Book Synopsis Durable Pt-based Catalysts for Oxygen Reduction Reaction in Fuel Cell by : Zeyan Liu
Download or read book Durable Pt-based Catalysts for Oxygen Reduction Reaction in Fuel Cell written by Zeyan Liu and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fuel cells are devices that can efficiently convert fuels into electricity without the limitation of the Carnot cycle. Particularly, hydrogen fuel cells have attracted enormous interest due to their high energy density, high efficiency, and low environmental impacts. The most widely adopted proton-exchange-membrane fuel cells (PEMFCs) use platinum (Pt) catalysts to drive both anode and cathode reactions. To date, the most significant roadblock to the broad dissemination of this green energy technology remains the acceleration and retention of the reaction rate of oxygen reduction reaction (ORR) at the cathode. Developing robust, active, and cost-effective ORR catalysts is the solution to this challenge.In my first work, I demonstrated a Cu doping strategy to enhance the intrinsic activity and durability of octahedral PtNi nanoparticles in the rotating-disk-electrode (RDE) setting. By a novel integration of simulations and growth tracking experiments, we uncover the beneficial role of increased surface Pt composition, which reduces the generation of surface vacancies and subsequent dissolution of sub-surface Cu and Ni atoms. Unlike the well-controlled RDE system, the critical role of mass transports in a practical membrane-electrode-assembly (MEA) system demands additional consideration in stability-enhancing strategies. Therefore, in my subsequent work, I recognized the critical challenge in MEA with ultralow Pt loading and designed a graphene-nanopocket-encaged platinum cobalt nanocatalyst with good electrochemical accessibility and exceptional durability in practical MEA testing. With the greatly improved rated power and durability, a 6.8 gram Pt loading is projected for a 90-kW PEMFC light-duty vehicle, approaching that used in a typical catalytic converter. Furthermore, I presented a unique design of ultrafine Pt nanocatalysts with embedded cobalt oxide clusters, which further improve the catalyst stability for durable PEMFCs. This endohedral-oxide design exploits the strong Pt/oxide interaction, which grants the catalyst its exceptional structural and chemical durability, without sacrificing activity. The developed nanocatalyst exhibits exceptional durability promising an outstanding projected lifetime of 15,000 hours.
Book Synopsis Electrocatalyst-support Interactions by :
Download or read book Electrocatalyst-support Interactions written by and published by . This book was released on 1978 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The maximum utilization of noble metals as heterogeneous catalysts is achieved by dispersing the noble metals as small particles supported on a porous, high surface area powder. In some studies with supported noble metal catalysts, it has been reported that the metal particle interacts with the support material and that the interaction affects the catalytic properties of the metal. Experimental studies on metal-support interactions that are pertinent to electrocatalysis will be discussed. Platinum supported on carbon black is one of the most active electrocatalysts for oxygen reduction in phosphoric acid fuel cells. In the acid environment at 100 to 200/sup 0/C, the Pt surface area decreases with time due to the growth of the supported Pt particles. The effects of a liquid-phase environment on the particle growth mechanism of supported Pt catalysts is discussed. 60 references.
Book Synopsis Synthesis and Characterization of Pt/TiO2/C Composite Catalysts for Fuel Cells Prepared Using a Glucose Modifier by : Christopher Odetola
Download or read book Synthesis and Characterization of Pt/TiO2/C Composite Catalysts for Fuel Cells Prepared Using a Glucose Modifier written by Christopher Odetola and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Catalysts in the electrodes of polymer exchange membrane fuel cells (PEMFCs) serve a critical function in reactions which can be used to generate electrical energy from chemical fuels. Pt nanoparticles are commonly dispersed on a conductive support and used as electrode materials in these devices because of their exceptional catalytic activity and electrochemical active surface area. The performance and stability of these electrodes strongly depend on the characteristics of the support. Catalysts supported on high surface area carbon black are widely used in low-temperature fuel cells. In PEMFCs, these catalyst materials can be exposed to high potential and low pH values, resulting in irreversible loss of activity that will limit the useful lifetime of the cell, ultimately leading to its failure. Pt is a noble metal which has good intrinsic stability, but carbon is not thermodynamically stable resulting in the corrosion of the catalyst support under these conditions. The design of more resilient platinum catalyst supports to carry out the successful reaction in a fuel cell's catalyst layer is required to extend the lifetime of PEMFCs degradation. In this thesis, two approaches were used to synthesize robust catalyst support materials for fuel cell applications. In the first case, carbon surfaces were functionalised to enhance their interactions with the catalyst and secondly, stable metal oxide was combined with modified carbon substrates, to maximise contacts within the composite electrocatalysts and to prevent carbon corrosion of a single phase carbon support catalyst. TiO2 NPs, were first chemically bonded to the surfaces of Vulcan carbon to help anchor the Pt catalyst nanoparticles through strong metal-support interactions. Validation of a dual phase catalyst support is an important goal of this research. Each material phase offers a unique advantage that can only be recognized by the preparation of a composite electrocatalyst. Pristine Vulcan (PV) was functionalised with glucose hydroxyl functional groups that react with the base titanium metal alkoxide in a sol-gel reaction and then calcined to form a more chemically crystalline surface. This is followed by impregnation reduction process to deposit the nanostructured Pt catalyst. Material characterization data of synthesized materials were used to correlate the effects of support structure and composition on resilient performance. Advantages from the TiO2/C supports toward performance and durability were contrasted against a set of control samples and demonstrated ex situ. The prepared composite catalysts showed substantial enhancements toward oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) as well as improved stability of the Pt-TiO2 heterogeneous interface formed between catalyst and support. The enhanced performance and durability of these composite catalysts is improved by applying the science of materials and interfaces to the synthesis of composite supports, thus serving as an example for further progress and optimization. Irradiation of these composite catalysts with UV-visible light also showed ~ 171 % photo enhanced activity for MOR, which clearly demonstrates a synergistic effect between the photo- and electrocatalysts. The comparison between the prepared catalysts indicates that there is an appropriate ratio of carbon and TiO2 to obtain the best performance of these photoelectroactive materials. These results demonstrate that methanol oxidation is achieved by electro- and photoelectrocatalysis using a simple and affordable method. This procedure can be conveniently exploited to enhance the response of direct methanol fuel cell electrodes.
Book Synopsis Fabrication of Metal–Organic Framework Derived Nanomaterials and Their Electrochemical Applications by : Wei Xia
Download or read book Fabrication of Metal–Organic Framework Derived Nanomaterials and Their Electrochemical Applications written by Wei Xia and published by Springer. This book was released on 2018-04-03 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis systematically introduces readers to a new metal-organic framework approach to fabricating nanostructured materials for electrochemical applications. Based on the metal-organic framework (MOF) approach, it also demonstrates the latest ideas on how to create optimal MOF and MOF-derived nanomaterials for electrochemical reactions under controlled conditions. The thesis offers a valuable resource for researchers who want to understand electrochemical reactions at nanoscale and optimize materials from rational design to achieve enhanced electrochemical performance. It also serves as a useful reference guide to fundamental research on advanced electrochemical energy storage materials and the synthesis of nanostructured materials.
