Investigating Flame Based Synthesis Of Carbon Nanotubes And Metal Oxide Nanowires
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Investigating Flame Based Synthesis Of Carbon Nanotubes And Metal Oxide Nanowires
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Author : Fusheng Xu
language : en
Publisher:
Release Date : 2007
Investigating Flame Based Synthesis Of Carbon Nanotubes And Metal Oxide Nanowires written by Fusheng Xu and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with Nanotubes categories.
The synthesis of carbon nanotubes (CNTs) and metal-oxide nanowires (e.g. ZnO, WO2.9) are examined experimentally by inserting probes into various flame geometries at atmospheric pressure. The main probed-flame configurations are the inverse co-flow diffusion flame (IDF) and the counter-flow diffusion flame (CDF), which are compared with each other to assess the translatability of local synthesis conditions in producing the same growth attributes and morphologies. The CDF is characterized using laser-based spontaneous Raman spectroscopy (SRS), and validated with simulations using detailed chemical kinetics and transport. SRS is used to measure local conditions in the 2-D axi-symmetric IDF. Properties of the as-synthesized nanostructures are determined by field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDXS), and resonance Raman spectroscopy (RRS). Various morphologies of CNTs are grown catalytically on metal-alloy substrates of different compositions (i.e., Fe, Fe/Cr, Ni/Cu, Ni/Ti, Ni/Cr, Ni/Cr/Fe), as well as on metal-oxide solid solutions (i.e. NiAl2O4, CoAl2O4 and ZnFe2O4). Vertically well-aligned multi-walled CNTs (MWNTs) with uniform diameters are obtained from Ni/Cr/Fe and Ni/Ti alloys. CNTs produced from ZnFe2O4 substrates are found to be a mixture of MWNTs and single-walled carbon nanotubes (SWNTs) with at least 30% SWNTs by number. Effects of local gas-phase temperature, substrate temperature, carbon-based precursor species concentrations, and substrate voltage bias on CNT formation, diameter, growth rate, yield, density, and morphology are investigated. Aligned single-crystal tungsten oxide nanowires with diameters of 20-50nm are grown directly from tungsten substrates at high rates, with local gas-phase temperature and chemical species specified at the substrate for self-synthesis. Voltage bias is shown to dramatically alter the morphologies of the as-synthesized WOx nanomaterial. Single-crystalline ZnO nanowires are grown directly on zinc-plated steel substrates at high rates with no catalysts. Larger-diameter (>100nm) nanowires are produced at higher temperatures; while smaller-diameter (25-40nm) nanowires are produced at lower temperatures, and only on the fuel side of the reaction zone. Reactions with H2O appear to be the dominant route for nanowire synthesis. Nanoribbons and other nanowire-based morphologies are also found and discussed.
Investigating Local Growth Conditions In The Flame Synthesis Of Metal Oxide Nanostructures
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Author : Cassandra D'Esposito
language : en
Publisher:
Release Date : 2009
Investigating Local Growth Conditions In The Flame Synthesis Of Metal Oxide Nanostructures written by Cassandra D'Esposito and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with Flame categories.
The synthesis of metal-oxide nanowires (i.e. WO2.9, ZnO, Cu2O, and Fe3O4) and nanoplates (i.e. MoO2) is examined experimentally with metal-substrate probes inserted into counter-flow diffusion flames (CDFs) at atmospheric pressure. The quasi-one-dimensional flow field allows for correlation between morphologies and local growth conditions, as well as the tailoring of the flame structure, through computational simulations with detailed chemical kinetics and transport, to provide conditions suitable for gas-phase growth of nanostructures. Comparisons of products synthesized between methane and hydrogen flames, as well as between locations probed on either the fuel side or the air side of the reaction zone, permit evaluation of the roles of O2 versus H2O versus CO2 in the oxidative route(s) involved. The as-synthesized nanostructures are characterized by field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), and energy dispersive X-ray spectroscopy (EDXS). Tungsten oxide nanowires are grown with diameters ranging from 50 to 200 nm at 1720K. The crystal structure is tetragonal WO2.9, but the growth directions vary with flame conditions. Single-crystal ZnO nanostructures are formed at 1000, 1300, and 1600K. All growth mechanisms are possible based on Gibbs free energy calculations. Molybdenum oxide nanoplates are grown in the methane flame at 2000K on both the air and fuel sides, where similar amounts of H2O and CO2 are found. In the hydrogen flame, oxidized structures are grown on the air side, and micron sized plates are synthesized on the fuel side. Cu2O nanowires are grown only on the air side of the methane and hydrogen flames, where large amounts of oxygen are present. The fuel sides of both flames show nucleation sites on the surface but no nanowire growth. Iron oxide nanowires are formed on the air side of the methane and hydrogen flames. Carbon nanotubes and nanowires are grown on the fuel side of the methane flame, while iron-oxide nodules are formed on the fuel side of the hydrogen flame.
Flame Synthesis And Applications Of Metal Oxide Nanowires
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Author : Pratap Mahesh Rao
language : en
Publisher:
Release Date : 2013
Flame Synthesis And Applications Of Metal Oxide Nanowires written by Pratap Mahesh Rao and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.
Herein, two novel methods for the flame synthesis of metal oxide nanowire arrays and related nanomaterials are developed and investigated. Both methods are rapid (micrometer/minute axial growth rate), atmospheric, controllable and scalable, and result in highly pure and crystalline materials. Simultaneously, these methods allow the growth of metal oxide nanowires on diverse, technologically relevant, and often delicate substrates. The first method is flame-heated solid phase diffusion growth, in which a metal substrate is rapidly heated to high temperatures by a flame, and metal oxide nanowires grow by metal diffusion out of the substrate in the hot, oxidative post-flame environment. The second is flame vapor deposition, in which the flame oxidizes and evaporates metals at high temperatures to produce large concentrations of oxide vapors that condense onto cooler substrates in the form of nanowires and other nanostructures. In each method, the chemical composition, growth rate and morphology (shape, packing density and alignment) of the nanostructures can be finely controlled by tuning flame parameters such as the fuel/air ratio and temperature, and substrate parameters such as surface energy and temperature. Moreover, an application of flame synthesized nanowires is demonstrated for the first time. As a result of superior morphology (increased length and packing density), the photoelectrochemical water-splitting performance of flame-synthesized tungsten trioxide nanowires is more than twice that of state of the art tungsten trioxide nanowire photoanodes synthesized by conventional hydrothermal and vapor deposition methods. These flame synthesis methods may enable future generations of technologies based on metal oxide nanowires to be developed and deployed on a large scale.
Nanomaterials Synthesis
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Author : Yasir Beeran Pottathara
language : en
Publisher: Elsevier
Release Date : 2019-05-29
Nanomaterials Synthesis written by Yasir Beeran Pottathara and has been published by Elsevier this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019-05-29 with Technology & Engineering categories.
Nanomaterials Synthesis: Design, Fabrication and Applications combines the present and emerging trends of synthesis routes of nanomaterials with the incorporation of various technologies. The book covers the new trends and challenges in the synthesis and surface engineering of a wide range of nanomaterials, including emerging technologies used for their synthesis. Significant properties, safety and sustainability and environmental impacts of the synthesis routes are explored. This book is an important information source that will help materials scientists and engineers who want to learn more about how different classes of nanomaterials are designed. Highlights recent developments in, and opportunities created by, new nanomaterials synthesis methods Explains major synthesis techniques for different types of nanomaterials Discusses the challenges of using a variety of synthesis methods
Flame Synthesis And Doping Of Metal Oxide Nanowires And Their Application In Solar Water Splitting
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Author : Lili Cai
language : en
Publisher:
Release Date : 2016
Flame Synthesis And Doping Of Metal Oxide Nanowires And Their Application In Solar Water Splitting written by Lili Cai and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
Considering the increasing energy and environmental problems associated with the exhaustible fossil fuels, renewable energy conversion devices have attracted tremendous attention, which hold the promise to supply the fuel and electricity in a sustainable way. For many of these devices, such as batteries, fuel cells, solar cells and solar water splitting cells, metal oxides are very important functional materials due to their earth abundance, good stability and diverse properties. Recently nanowire-based metal oxides have enabled revolutionary advances in various energy conversion devices, because of their unique physical and chemical properties resulting from the high aspect ratio and large surface area. Despite their advantages, practical applications of metal oxide nanowires are hindered, as conventional synthesis methods have limitations for large scale production. Flame synthesis can potentially solve this large-scale production issue for metal oxide nanowires, given its demonstrated scalability in the industrial production of nanoparticles. However, only until very recently has flame synthesis been applied to metal oxide nanowires. More research is needed to develop advanced flame synthesis method for metal oxide nanowires, to understand the mechanism to well control the size, shape and compositions for reliable manufacture, and to evaluate their quality and functionalities in real devices. This thesis presents a novel flame vapor deposition method for the synthesis of metal oxide nanowires with the capabilities of rapid rate, good uniformity over large area and broad substrate choice. Through the investigation of growth mechanism, good control over the morphology and composition was achieved by tuning the process parameters such as fuel/air ratio, source temperature, substrate material and temperature. In addition to synthesis, flame-based doping method (sol-flame doping) was innovated for controllable doping of metal oxide NWs to modify the properties of host materials at the nanometer scale. This sol-flame doping method not only preserves the morphology and crystallinity of the host NWs, but also allows fine control over the dopant concentration by simply varying the concentration of dopant precursor solution. With this method, significant enhancement of the electrocatalytic activity towards oxygen evolution reaction was achieved for TiO2 NWs (up to 760 mV reduction of the overpotential), attributing to simultaneously improved surface charge transfer kinetics and increased bulk conductivity by doping. Finally, the flame-synthesized metal oxide nanowires were implemented as a photoanode in photoelectrochemical water splitting. By rational design and scalable fabrication, the WO3/BiVO4/Ni:FeOOH composite nanowire photoanode generated a high photocurrent of 4.5 mA/cm2 at a potential of 1.23 VRHE under simulated sunlight, which is among the highest produced by any WO3/BiVO4 based photoanodes. With the demonstrated rapid rate, good controllability and superior performance of the flame-produced metal oxide nanowires, these flame synthesis and doping methods can potentially enable future generation of energy devices by removing the barrier for large-scale production of tailored metal oxide nanowires.
Investigating The Synthesis Of Transition Metal Oxide Nanostructures In A Counter Flow Flame
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Author : Moien Farmahini-Farahani
language : en
Publisher:
Release Date : 2014
Investigating The Synthesis Of Transition Metal Oxide Nanostructures In A Counter Flow Flame written by Moien Farmahini-Farahani and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with Combustion categories.
Combustion Chemistry And The Carbon Neutral Future
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Author : Kenneth Brezinsky
language : en
Publisher: Elsevier
Release Date : 2023-02-16
Combustion Chemistry And The Carbon Neutral Future written by Kenneth Brezinsky and has been published by Elsevier this book supported file pdf, txt, epub, kindle and other format this book has been release on 2023-02-16 with Science categories.
As the demands for cleaner, more efficient, reduced and zero carbon emitting transportation increase, the traditional focus of Combustion Chemistry research is stretching and adapting to help provide solutions to these contemporary issues. Combustion Chemistry and the Carbon Neutral Future: What will the Next 25 Years of Research Require? presents a guide to current research in the field and an exploration of possible future steps as we move towards cleaner, greener and reduced carbon combustion chemistry. Beginning with a discussion of engine emissions and soot, the book goes on to discuss a range of alternative fuels, including hydrogen, ammonia, small alcohols and other bio-oxygenates, natural gas, syngas and synthesized hydrocarbon fuels. Methods for predicting and improving efficiency and sustainability, such as low temperature and catalytic combustion, chemical looping, supercritical fluid combustion, and diagnostic monitoring even at high pressure, are then explored. Some novel aspects of biomass derived aviation fuels and combustion synthesis are also covered. Combining the knowledge and experience of an interdisciplinary team of experts in the field, Combustion Chemistry and the Carbon Neutral Future: What will the Next 25 Years of Research Require? is an insightful guide to current and future focus areas for combustion chemistry researchers in line with the transition to greener, cleaner technologies. Provides insight on current developments in combustion chemistry as a tool for supporting a reduced-carbon future Reviews modeling and diagnostic tools, in addition to key approaches and alternative fuels Includes projections for the future from leaders in the field, pointing current and prospective researchers to potentially fruitful areas for exploration
Carbon And Oxide Nanostructures
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Author : Noorhana Yahya
language : en
Publisher: Springer
Release Date : 2013-02-27
Carbon And Oxide Nanostructures written by Noorhana Yahya and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-02-27 with Technology & Engineering categories.
This volume covers all aspects of carbon and oxide based nanostructured materials. The topics include synthesis, characterization and application of carbon-based namely carbon nanotubes, carbon nanofibres, fullerenes, carbon filled composites etc. In addition, metal oxides namely, ZnO, TiO2, Fe2O3, ferrites, garnets etc., for various applications like sensors, solar cells, transformers, antennas, catalysts, batteries, lubricants, are presented. The book also includes the modeling of oxide and carbon based nanomaterials. The book covers the topics: Synthesis, characterization and application of carbon nanotubes, carbon nanofibres, fullerenes Synthesis, characterization and application of oxide based nanomaterials. Nanostructured magnetic and electric materials and their applications. Nanostructured materials for petro-chemical industry. Oxide and carbon based thin films for electronics and sustainable energy. Theory, calculations and modeling of nanostructured materials.
Multiple Inverse Diffusion Flame Synthesis Of Carbon Nanomaterials
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Author : Nasir K. Memon
language : en
Publisher:
Release Date : 2012
Multiple Inverse Diffusion Flame Synthesis Of Carbon Nanomaterials written by Nasir K. Memon and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with Carbon categories.
Carbon nanomaterials exhibit many remarkable electrical and physical properties. An ongoing challenge associated with specific novel carbon nanomaterials, such as graphene, is the development of large-scale production methods at low cost. The broad objective of this work is to investigate flame synthesis of carbon nanomaterials, specifically graphene and carbon nanotubes (CNTs), using open-atmosphere processing, with an eye towards scalability. An experimental study using a novel setup, based on multiple inverse-diffusion flames is undertaken to investigate the direct flame-synthesis of CNTs and graphene on metal substrates. Few-layer graphene (FLG) is grown on copper and nickel substrates at high rates using the novel flame-synthesis burner. Substrate material (i.e. copper, nickel, cobalt, iron, and copper-nickel alloy), along with its temperature and hydrogen pretreatment, strongly impacts the quality and uniformity of the graphene films. The growth of FLG occurs in the temperature range 750-950°C for copper and 600-850°C for nickel and cobalt. For iron, the growth of graphene is not exclusively observed. CNT growth is observed on a number of substrates. Transitional growth between CNTs and graphene films occurs on nickel and nickel alloys, depending on composition and temperature. For nickel, copper-nickel, nitinol, and Inconel substrates, CNTs grow at 500°C. The transitional growth to few-layer graphene is observed on nickel, copper-nickel and Inconel by changing the substrate temperature to 850°C. The growth of graphene is not observed on nitinol for the examined experimental conditions. The growth of few-layer graphene films and CNTs are also investigated using various metal-oxide spinels as catalysts. The growth of CNTs is examined on NiAl2O4, CoAl2O4 and ZnFe2O4 using counterflow diffusion flame and multiple inverse-diffusion flames, while the growth of graphene is examined on CuFe2O4 using multiple inverse-diffusion flames. Finally, the growth of CNTs and iron oxide is studied on stainless steel. At low temperatures (500oC) the growth of [alpha]-Fe2O3 is observed, while at higher temperatures (850oC) the growth of CNTs is observed. Additionally, by following a two-step growth process, where the temperature is changed from 500oC to 850oC, the growth of CNTs and [gamma]-Fe2O3 occurs.
One Dimensional Iii V Nitride Tansitional Metal Oxide Nanowires And Single Walled Carbon Nanotubes
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Author : Song Han
language : en
Publisher:
Release Date : 2005
One Dimensional Iii V Nitride Tansitional Metal Oxide Nanowires And Single Walled Carbon Nanotubes written by Song Han and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with categories.