Chemisorption of Molecular Hydrogen on Carbon Nanotubes: A Route to Effective Hydrogen Storage

The energetics of the chemisorption of molecular hydrogen on small-diameter armchair carbon nanotubes has been investigated using first-principles density functional theory (DFT). The adsorption of hydrogen was examined at a range of coverages, from low to full monolayer coverage. Several pathways f...

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Main Authors: Bilic, Ante, Gale, Julian
Format: Journal Article
Published: American Chemical Society 2008
Online Access:http://hdl.handle.net/20.500.11937/40760
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author Bilic, Ante
Gale, Julian
author_facet Bilic, Ante
Gale, Julian
author_sort Bilic, Ante
building Curtin Institutional Repository
collection Online Access
description The energetics of the chemisorption of molecular hydrogen on small-diameter armchair carbon nanotubes has been investigated using first-principles density functional theory (DFT). The adsorption of hydrogen was examined at a range of coverages, from low to full monolayer coverage. Several pathways for hydrogenation were investigated, and those that could lead to energetically favorable, stable structures of fully saturated nanotubes were identified. For these routes, the calculations indicate that the addition of hydrogen, apart from at the very onset, is exothermic and also becomes increasingly more favorable with increasing degree of coverage. Carbon nanotubes of sufficiently small diameter are shown to have the capacity to store a full monolayer of hydrogen effectively via chemisorption. In addition, kinetic barriers for the dissociative chemisorption of H2 and thermal equilibration of the system were considered. These were found to be quite large for admolecules on an otherwise-clean nanotube, but to drop substantially in the vicinity of preadsorbed hydrogen; that is, the adsorbed hydrogen acts as an autocatalyst for further hydrogenation. On the basis of these findings, the chemical reaction of hydrogen with carbon nanotubes is expected to become increasingly exothermic and also to proceed more rapidly at higher coverages.
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spelling curtin-20.500.11937-407602017-09-13T15:57:40Z Chemisorption of Molecular Hydrogen on Carbon Nanotubes: A Route to Effective Hydrogen Storage Bilic, Ante Gale, Julian The energetics of the chemisorption of molecular hydrogen on small-diameter armchair carbon nanotubes has been investigated using first-principles density functional theory (DFT). The adsorption of hydrogen was examined at a range of coverages, from low to full monolayer coverage. Several pathways for hydrogenation were investigated, and those that could lead to energetically favorable, stable structures of fully saturated nanotubes were identified. For these routes, the calculations indicate that the addition of hydrogen, apart from at the very onset, is exothermic and also becomes increasingly more favorable with increasing degree of coverage. Carbon nanotubes of sufficiently small diameter are shown to have the capacity to store a full monolayer of hydrogen effectively via chemisorption. In addition, kinetic barriers for the dissociative chemisorption of H2 and thermal equilibration of the system were considered. These were found to be quite large for admolecules on an otherwise-clean nanotube, but to drop substantially in the vicinity of preadsorbed hydrogen; that is, the adsorbed hydrogen acts as an autocatalyst for further hydrogenation. On the basis of these findings, the chemical reaction of hydrogen with carbon nanotubes is expected to become increasingly exothermic and also to proceed more rapidly at higher coverages. 2008 Journal Article http://hdl.handle.net/20.500.11937/40760 10.1021/jp802104n American Chemical Society restricted
spellingShingle Bilic, Ante
Gale, Julian
Chemisorption of Molecular Hydrogen on Carbon Nanotubes: A Route to Effective Hydrogen Storage
title Chemisorption of Molecular Hydrogen on Carbon Nanotubes: A Route to Effective Hydrogen Storage
title_full Chemisorption of Molecular Hydrogen on Carbon Nanotubes: A Route to Effective Hydrogen Storage
title_fullStr Chemisorption of Molecular Hydrogen on Carbon Nanotubes: A Route to Effective Hydrogen Storage
title_full_unstemmed Chemisorption of Molecular Hydrogen on Carbon Nanotubes: A Route to Effective Hydrogen Storage
title_short Chemisorption of Molecular Hydrogen on Carbon Nanotubes: A Route to Effective Hydrogen Storage
title_sort chemisorption of molecular hydrogen on carbon nanotubes: a route to effective hydrogen storage
url http://hdl.handle.net/20.500.11937/40760