Gas Adsorption Studies On Vertically Aligned Carbon Nanotubes
DOWNLOAD
Download Gas Adsorption Studies On Vertically Aligned Carbon Nanotubes PDF/ePub or read online books in Mobi eBooks. Click Download or Read Online button to get Gas Adsorption Studies On Vertically Aligned Carbon Nanotubes book now. This website allows unlimited access to, at the time of writing, more than 1.5 million titles, including hundreds of thousands of titles in various foreign languages. If the content not found or just blank you must refresh this page
Gas Adsorption Studies On Vertically Aligned Carbon Nanotubes
DOWNLOAD
Author : Deepu Joseph Babu
language : en
Publisher:
Release Date : 2016
Gas Adsorption Studies On Vertically Aligned Carbon Nanotubes written by Deepu Joseph Babu 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.
Study On The Horizontally Aligned And Vertically Aligned Carbon Nanotubes For The Applications In Gas Ionization Sensors And Supercapacitors
DOWNLOAD
Author :
language : en
Publisher:
Release Date : 2017
Study On The Horizontally Aligned And Vertically Aligned Carbon Nanotubes For The Applications In Gas Ionization Sensors And Supercapacitors written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with categories.
Reliable Growth Of Vertically Aligned Carbon Nanotube Arrays By Chemical Vapor Deposition And In Situ Measurement Of Fundamental Growth Kinetics In Oxygen Free Conditions
DOWNLOAD
Author : JUNG BIN. IN
language : en
Publisher:
Release Date : 2011
Reliable Growth Of Vertically Aligned Carbon Nanotube Arrays By Chemical Vapor Deposition And In Situ Measurement Of Fundamental Growth Kinetics In Oxygen Free Conditions written by JUNG BIN. IN and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
Vertically-aligned carbon nanotube (VACNT) arrays are both an important technological system, and a fascinating system for studying basic principles of nanomaterial synthesis. However, despite continuing efforts for the past decade, important questions about this process remain largely unexplained. Recently, nanotube research investigations have been conducted, aiming at revealing the underlying growth mechanisms, rather than merely studying the feasibility on new growth methods. Nonetheless, growth deactivation and the accompanying termination mechanisms still remain a topic of nanotube synthesis science. Due to the extremely small size, however, direct characterization of various transport and conversion events occurring at the catalyst surface is not an easy task. Thus investigations on growth kinetics are the first step to resolve questions about growth mechanism. Before exploring kinetic aspects of the growth process, one must achieve reliable growth conditions since growth non-reproducibility retards obtaining reliable growth data and undermines the scientific value of the data. In order to improve growth reliability, several factors that may contribute to growth non-reproducibility were identified and thereafter mitigated. Firstly, a simulation study was conducted to achieve insight into temperature and velocity profile of gases inside the reactor since gas flow dynamics can render growth environment near the substrate non-uniform. Interestingly, when argon gas was used as the main carrier gas, natural convective flow emerged, generating flow circulation before the gas reached the substrate placed at the center of the tube reactor. This flow circulation was not favorable for controlled gas introduction. This problem could be resolved by using a more heat- and momentum- conductive gas such as helium. Secondly, atomic force microscopy of annealed catalyst revealed that the aluminum sub-layer was not thermally stable at the growth temperature although this material has been widely used as a barrier layer to avoid silicide formation of catalyst on silicon substrates. In this respect, aluminum oxide should be a better choice, but under-stoichiometry of the aluminum oxide layer, which originated from sputter target degradation, affected thermal stability of the layer. Reactive sputtering by oxygen addition greatly enhanced thermal stability, and finally defect-free catalyst nanoparticles were formed by thermal annealing. Thirdly, the effect of the small part-per-million levels of oxygen-containing species on VACNT growth revealed that oxygen-containing gas impurities in nominally pure gas sources have a great influence on growth kinetics in a positive way; their presence increases catalyst lifetime and growth yield. However, the kinetic behavior that is highly sensitive to gas purity is prone to showing an interfering kinetic trend where the real mechanism is masked by the significant gas impurity effect. The stark difference in catalytic lifetime after the introduction of high-performance gas purifiers shows that extremely tight control of the reaction gas composition purity is necessary to obtain controlled growth of CNTs under atmospheric chemical vapor deposition (CVD) conditions. Finally, more reliable growth of VACNTs was achieved, and thereafter the next step for fundamental growth kinetics measurement was followed. Finally, the CVD system was equipped with an optical micrometer that enables in-situ measurement of the height of growing VACNTs, which have advantageous structure facilitating measurement of growth kinetics since the array height has a robust correlation with growth yield and thereby growth rate. Various ethylene and hydrogen combinations were examined to capture growth kinetics related to different gas environment. The measured initial growth rates were linearly proportional to ethylene concentration, whereas a reciprocal relation was observed with respect to hydrogen concentration. The apparent activation energy was higher than reported in references. Flow rate variation experiments revealed that gas phase reaction is involved as the crucial growth step, which supports the observed high activation energy. Consequently, a growth model was proposed so that it could reasonably fit the initial growth rate data. Kinetic aspects related to growth deactivation were explored by measuring the final growth height and catalyst lifetime. Unlike growth with unpurified gases, growth became much less sensitive to gas composition after purification. Importantly, it was observed that growth deactivates by deficit of carbon source when relatively low ethylene was introduced. This result is surprising since ethylene pressure should be high enough at the catalyst, considering the calculated sticking coefficient of ethylene is very low, approximately 10^-5. Thus it substantiates the idea that catalyst-mediated gas pretreatment process is critical to sustain nanotube growth. Importantly, this idea challenges the widely accepted growth termination concept whereby nanotube stops growing due to catalyst encapsulation by excessive carbon. Indeed, reduced flow rate of gas mixture increased growth yield remarkably by promoting the gas pretreatment over the catalyst. Catalyst ripening, or steric hindrance by interaction of nanotubes can be an alternative reason for growth termination, but analysis of morphologies of the annealed catalyst and as-grown nanotubes revealed that their effects were not significant for the corresponding growth conditions.
Aligned Carbon Nanotubes As Porous Materials For Selective Gas Adsorption
DOWNLOAD
Author : Mahshid Rahimi
language : en
Publisher:
Release Date : 2016
Aligned Carbon Nanotubes As Porous Materials For Selective Gas Adsorption written by Mahshid Rahimi 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.
Carbon Nanomaterials For Gas Adsorption
DOWNLOAD
Author : Maria Letizia Terranova
language : en
Publisher: CRC Press
Release Date : 2012-11-27
Carbon Nanomaterials For Gas Adsorption written by Maria Letizia Terranova and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-11-27 with Technology & Engineering categories.
Research in adsorption of gases by carbon nanomaterials has experienced considerable growth in recent years, with increasing interest for practical applications. Many research groups are now producing or using such materials for gas adsorption, storage, purification, and sensing. This book provides a selected overview of some of the most interesting scientific results regarding the outstanding properties of carbon nanomaterials for gas adsorption and of interest both for basic research and technological applications. Topics receiving special attention in this book include storage of H, purification of H, storage of rare gases, adsorption of organic vapors, gas trapping and separation, and metrology of gas adsorption.
Gas Adsorption On Suspended Carbon Nanotubes And Graphene
DOWNLOAD
Author : Boris Dzyubenko
language : en
Publisher: Boris Dzyubenko
Release Date : 2017-08-18
Gas Adsorption On Suspended Carbon Nanotubes And Graphene written by Boris Dzyubenko and has been published by Boris Dzyubenko this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017-08-18 with Science categories.
Rare gas adsorption was studied on suspended individual single walled carbon nanotubes and graphene. The devices were fabricated as field effect transistors. Adsorption of N2 and CO, which formed a Root 3 X Root 3 commensurate solid monolayer, produced a dramatic reduction of the two-terminal conductance of graphene by as much as a factor of three. This effect is possibly connected with the opening of a band gap expected to occur in such structures.
Purification And Gas Adsorption Studies Of Single Walled Carbon Nanotubes
DOWNLOAD
Author : Katherine E. H. Gilbert
language : en
Publisher:
Release Date : 2005
Purification And Gas Adsorption Studies Of Single Walled Carbon Nanotubes written by Katherine E. H. Gilbert and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with Carbon categories.
Vertically Aligned Carbon Nanotubes Synthesis On Nanostructured Porous Silicon Template In Short Time
DOWNLOAD
Author : N.A.Asli
language : en
Publisher:
Release Date : 2012
Vertically Aligned Carbon Nanotubes Synthesis On Nanostructured Porous Silicon Template In Short Time written by N.A.Asli and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with categories.
Hierarchical Porous Structures With Aligned Carbon Nanotubes As Efficient Adsorbents And Metal Catalyst Supports
DOWNLOAD
Author : Hema Vijwani
language : en
Publisher:
Release Date : 2015
Hierarchical Porous Structures With Aligned Carbon Nanotubes As Efficient Adsorbents And Metal Catalyst Supports written by Hema Vijwani and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with Carbon nanotubes categories.
The overall goal of this study is two-fold: synthesis of multiscale nanostructures by growing aligned carbon nanotubes on porous foam substrates and investigation of their applicability as adsorbents and catalyst supports for environmental remediation applications. High purity, vertically-aligned arrays of carbon nanotubes (CNT) are grown on open-cell interconnected porous carbon foams by pre-activating them with an oxide buffer layer followed by chemical vapor deposition (CVD). This type of hierarchical morphology provides the capability of increasing surface area by several orders of magnitude, while tuning its morphology for targeted applications. Analytical models are also proposed in this study for specific surface area calculations, those agree well with the experimental measurements. These hierarchical carbon materials are seen to be powerful adsorbents of aqueous pollutants such as methylene blue dye. Their monolayer adsorption capacities correlate very well with the total CNT surface area determined from analytical models and with BET measurements, indicating full utilization of the nanotube surfaces. The hierarchical structures can also serve as base supports for attachment of metal nanoparticle catalysts. The catalysts investigated in this study are metallic palladium (Pd), oxidized palladium (PdO), and silver-palladium (Ag-Pd) nanoparticles combination. These are suitable for a variety of industrial applications such as hydrocarbon conversion, hydrogen storage, fuel cell electrodes and pollutant degradation. The current architecture allows synthesis of highly active catalyst structures utilizing very small quantities of precious metal that make the catalyst component significantly lighter and more compact than conventional systems. Detailed characterization of structure and surface chemical states of these nano-catalysts have been performed and their catalytic activities are tested by measuring the degradation kinetics of organic contaminants via bench-scale experiments. Catalytic degradation of atrazine, an emerging problematic contaminant, was quantified using high-performance liquid chromatography. Among Pd, PdO, and Ag-Pd nanoparticles, PdO in the presence of hydrogen was seen to provide the most rapid reaction rate. These nanocatalysts also enable rapid degradation of chlorinated hydrocarbons such as trichloroethylene and trichloroethane quantified using head-space gas chromatography, with PdO providing the fastest kinetic route. Durability tests indicated that the nano-particles and nanotubes are robust, and remain attached to the base support after long periods of rapid rotation in water. These results imply that such materials can provide compact and powerful surface active materials in future applications such as adsorbents, catalysts, porous electrodes, and energy storage devices.
Controlled Growth Of Vertically Aligned Carbon Nanotubes On Metal Substrates
DOWNLOAD
Author : Zhaoli Gao
language : en
Publisher:
Release Date : 2014
Controlled Growth Of Vertically Aligned Carbon Nanotubes On Metal Substrates written by Zhaoli Gao and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with Carbon nanotubes categories.