Adsorption Studies Of Simple Gases On As Produced Single Walled Carbon Nanotubes
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Adsorption Studies Of Simple Gases On As Produced Single Walled Carbon Nanotubes
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Author : Saikat Talapatra
language : en
Publisher:
Release Date : 2002
Adsorption Studies Of Simple Gases On As Produced Single Walled Carbon Nanotubes written by Saikat Talapatra and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2002 with categories.
Purification And Gas Adsorption Studies Of Single Walled Carbon Nanotubes
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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.
Gas Adsorption On Suspended Carbon Nanotubes And Graphene
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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.
Carbon Nanomaterials For Gas Adsorption
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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 Science 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 interestin
Gas Adsorption In As Prepared And Purified Single Walled Carbon Nanotubes
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Author : Amit B. Patel
language : en
Publisher:
Release Date : 2001
Gas Adsorption In As Prepared And Purified Single Walled Carbon Nanotubes written by Amit B. Patel and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2001 with Adsorption categories.
Gas Adsorption On Suspended Carbon Nanotubes And Graphene
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Author : Boris Dzyubenko
language : en
Publisher:
Release Date : 2017
Gas Adsorption On Suspended Carbon Nanotubes And Graphene written by Boris Dzyubenko 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.
Rare gas adsorption was studied on suspended individual single walled carbon nanotubes and graphene. The devices were fabricated as field effect transistors. Adsorption on graphene was studied through two-terminal conductance. On nanotube devices adsorption was studied through conductance while the coverage (density) of the adsorbates was determined from the mechanical resonance frequency shifts. The adsorbed atoms modified the conductance of the nanotube field effect transistors, in part through charge transfer from the adsorbates to the nanotube. By tracking the shifts of conductance as a function of gate voltage, G=G(Vg), and comparing these shifts with the periodicity of the Coulomb blockade oscillations we quantified the charge transfer to the nanotubes with high accuracy. For all studied gases (He, Ar, Kr, Xe, N2, CO, and O2) the charge transfer had a similar magnitude and was rather small, on the order of 10^-5 to 10^-3 electrons per adsorbed atom. The nanotube devices displayed two classes of adsorption behavior. On some devices the monolayers exhibited first-order phase transitions analogous to those that occur in adsorbed monolayers on graphite. On other devices phase transitions within the adsorbed monolayers were absent. We present evidence that a highly uniform layer of contaminants deposits on the surface of suspended nanotube devices either upon cooldown in the cryostat or at room temperature from air. These contaminants modify the adsorption behavior preventing the adsorbed monolayers from exhibiting the first order phase transitions expected to occur on a clean surface. A similar type of contamination leading to virtually identical effects occurs on suspended graphene. In the low coverage regions of isotherms on nanotubes we observe Henry's law behavior, demonstrating a high uniformity of the surface and allowing us to accurately determine the single particle binding energy to this surface. The determined binding energies were 776+-10 K for Ar, and 997+-37 K for Kr. In the second part of the dissertation we present the first measurements of adsorption on a pristine graphene surface, exposed through aggressive electric current annealing. On graphene the rare gas adsorbates form monolayers with phases analogous to those on graphite, but with phase transitions occurring at slightly higher pressures due to a reduction of binding energy. The condensations of monolayers with phases not commensurate with the graphene lattice resulted in a slight shift of the charge neutrality point of monolayer graphene corresponding to a change of carrier concentration on the order of 10^9 e/cm^2. 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. We observe hysteretic behavior in the adsorbed Root 3 X Root 3 commensurate monolayers on freestanding graphene, which is likely due to the interaction of two adsorbed monolayers on opposite surfaces of the graphene sheet.
Study Of Gas Adsorption On As Produced And Modified Carbon Nanotubes
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Author : Dinesh Singh Rawat
language : en
Publisher:
Release Date : 2010
Study Of Gas Adsorption On As Produced And Modified Carbon Nanotubes written by Dinesh Singh Rawat and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with categories.
Volumetric adsorption isotherm measurements were used to study the adsorption characteristics of ethane and butane on as-produced single-walled carbon nanotubes. Two adsorption substeps were obtained for each alkane molecule. However, the size of the high pressure substep was found to be gradually smearing with the increase in size of the adsorbed molecule. This phenomenon is interpreted as size entropy effect for linear molecules. Kinetics measurements of alkane adsorption on SWNTs were also conducted and their dependence on the molecular length was determined. Similar adsorption measurements were performed for Argon (Ar) on as-produced single-walled carbon nanotubes and nanotubes that were structurally modified using acid treatment. Enhancement of the sorptive capacity and the presence of two distinct kinetics of gas adsorption verified partial opening of single walled carbon nanotubes as a result of chemical treatment. Multiwalled carbon nanotubes were exposed to oxygen plasma treatment for varying time periods. Afterwards, adsorption measurements of Methane (CH 4) were conducted on untreated and oxygen plasma treated tubes. The presence of an additional substep, after exposing multiwalled carbon nanotubes to oxygen plasma for varying time periods, suggested progressive cleaning of nanotube surface.
Adsorption Of Noble Gases On Individual Suspended Single Walled Carbon Nanotubes
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Author : Hao-Chun Lee
language : en
Publisher:
Release Date : 2013
Adsorption Of Noble Gases On Individual Suspended Single Walled Carbon Nanotubes written by Hao-Chun Lee 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.
The focus of this work is a study of the adsorption of noble gases on individual, suspended, single-walled carbon nanotubes (SWNTs). The surface of a SWNT is a cylindrical cousin of graphite, but the binding energy is smaller and the cylindrical geometry and lack of grain boundaries could be expected to lead to substantially different behavior. The coverage (areal density) on a nanotube can be measured with high precision from the mechanical resonance frequency shifts, yielding isotherms as a function of gas pressure analogous to volumetric isotherms on bulk substrates. The electrical conductance of the nanotubes can also be measured at the same time and the effects of the adsorbates on the conductance thereby investigated. We found that adsorbed noble gases form monolayers on SWNTs, analogous to those on conventional 2-dimensional (2D) substrates, with a variety of 2D phases as a result of atom-atom interactions. Based on a combination of the coverage and conductance isotherms, the behavior of the adsorbates on SWNTs was established, including the 2D phases, 2D critical and triple-point temperatures, binding energies, isosteric heats, and latent heats. The majority of measurements were on Ar and Kr, fewer on 4He and Xe. The binding energy of the noble gases on a SWNT was found to be lower than on graphite, as anticipated. For example, the binding energy for Ar on one device was about 725 K ℗ł 50 K, about 30% lower than graphite. The lower binding energy allows isotherm measurements at lower temperatures compared because the required pressure are higher. In all cases we found that only a single atomic layer is formed before reaching the saturated vapor pressure of the adsorbate. Remarkably, although the binding energies of Ar were consistent between multiple SWNTs, the adsorbates on different devices did not behave in the same way. The device can be classified into two classes. Those in Class I show sharp first-order transitions between 2D phases, very similar to those on graphite, and the maximum monolayer coverage on SWNTs is consistent with that on graphite taking into account the radius of nanotube. Large and sharp risers at constant pressures in the coverage or conductance isotherms indicate the 2D liquid-vapor or commensurate solid-vapor conversion. Small and smoother risers following the large ones in the isotherms indicate the 2D incommensurate solid-liquid phase transitions. In contrast, devices in Class II do not show clear phase transitions, have non-vertical isotherms in regions where first-order jumps would be expected, and the monolayers seem to be not complete when the saturated vapor pressure is reached. The difference in isosteric heat between devices of the two classes within the region where the first-order transition is expected, may be due to the 2D L-V latent heat. The existence of the two different classes of behavior remains puzzling. It appears that in class II nanotubes the effects of atom-atom attractive interactions are suppressed, due possibly either to geometrical effects or the different electrical properties of different nanotube species.
Kinetics Of Methane Adsorption On Hipco Purified Single Walled Carbon Nanotubes
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Author : Murat Bulut
language : en
Publisher:
Release Date : 2008
Kinetics Of Methane Adsorption On Hipco Purified Single Walled Carbon Nanotubes written by Murat Bulut and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008 with categories.
Opening the ends of single-walled carbon nanotubes (SWNTs) has many technical as well as fundamental importance. However, during the purification process, the ends of the single-walled carbon nanotubes (SWNTs) are blocked due to the attachment of chemical functional groups. Previous studies concluded that the ends of the SWNTs can be opened by thermal activation which may result in an increase in the gas storage capacity of the nanotubes. In this study we focus on the effect of thermal activation. Two different samples of HiPco purified SWNTs from the same production line were thermally activated at 573 K and 673 K. The effects of thermal activation were observed through adsorption kinetic measurements of methane adsorption on these samples. Comparative study of these measurements revealed the evidence of opening the SWNTs by thermal activation.
Carbon Nanomaterials And Their Composites As Adsorbents
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Author : J. Tharini
language : en
Publisher: Springer Nature
Release Date :
Carbon Nanomaterials And Their Composites As Adsorbents written by J. Tharini and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on with categories.