Reaction Kinetics of the Atomic Oxygen-Graphite System

Gleit, Chester E.; Holland, W.D.; Wrigley, R. C.

doi:10.1038/200069a0

Cited by 11 publications

(5 citation statements)

References 6 publications

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“…This was confirmed by Gleit et aZ. 6 who found the reaction of atomic oxygen with a spectroscopically-pure graphite to be temperature dependent in the range 215 to 300"C, having an activation energy of 6.5 kcal mole-1. The temperature dependence of the radiolytic oxidation by carbon dioxide (presumably due to the production of atomic oxygen) of a pile-grade graphite has been studied by Gow and Marsh 7 who found an almost zero activation energy up to temperatures of 625°C (cp.…”

supporting

confidence: 53%

Oxidation of carbons and graphites by atomic oxygen kinetic studies

Marsh¹,

O'Hair²,

Wynne‐Jones³

1965

Trans. Faraday Soc.

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The oxidation of three amorphous carbons and an artificial graphite by atomic oxygen has been studied in the temperature range 14 to 350'C. The plasma of the radio-frequency discharge used to produce oxygen atoms was not in contact with the carbon sample. The rate of oxidation, at a fixed temperature, is dependent upon the duration of the experiment. This rate is also temperature dependent and activation energies of 9.9 to 10-8 kcal mole-1 are reported. The reaction is approximately first order with respect to atomic oxygen concentration. The rate of oxidation of the carbons, at constant temperature and concentration of atomic oxygen, is not influenced appreciably by the wide variations shown by the carbons in their chemical composition, internal surface area and poresizes, and degree of crystallinity. At temperatures above 200°C, the measured activation energy decreases and approaches almost zero at 350°C. The several factors, to which this is attributable, are discussed and evidence produced to show that surface-oxide can retard the rate of oxidation. For one carbon, surface-oxide is formed more readily from atomic oxygen than from molecular oxygen. The activation energy of gasification by atomic oxygen, and its relevance to the understanding of the mechanism of the reaction of molecular oxygen with carbon, is discussed.

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confidence: 53%

Oxidation of carbons and graphites by atomic oxygen kinetic studies

Marsh¹,

O'Hair²,

Wynne‐Jones³

1965

Trans. Faraday Soc.

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“…Experimentally, Gleit et al reported the reaction kinetics of atomic oxygen with graphitic carbon in the temperature range of 215À300 °C. 18 Blyholder and Eyring reported the kinetics of graphite oxidation using O 2 in the temperature range of 600À 1300 °C. 19,20 Bennett et al have investigated the vacuum ultraviolet photodissociation of molecular oxygen physisorbed on graphite.…”

Section: Introductionmentioning

confidence: 99%

“…The interactions and reactions for O x ( x = 1 and 2, atomic or molecular oxygen) with graphite have brought great interest to scientists because of important applications of graphite since the 1960s. Experimentally, Gleit et al reported the reaction kinetics of atomic oxygen with graphitic carbon in the temperature range of 215–300 °C . Blyholder and Eyring reported the kinetics of graphite oxidation using O 2 in the temperature range of 600–1300 °C. , Bennett et al have investigated the vacuum ultraviolet photodissociation of molecular oxygen physisorbed on graphite .…”

Section: Introductionmentioning

confidence: 99%

Quantum Chemical Prediction of Reaction Pathways and Rate Constants for the Reactions of O_x (x = 1 and 2) with Pristine and Defective Graphite (0001) Surfaces

Chen

Lin

2012

J. Phys. Chem. C

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We present reaction pathways for adsorption reactions of the O atom and O 2 molecule in the pristine and monovacancy defective graphite (0001) based on quantum chemical potential energy surfaces (PESs) obtained by the dispersion-augmented densityfunctional tight-binding (DFTB-D) method. We use a dicircumcoronene C 96 H 24 (L0D) graphene slab as the pristine graphite (0001) model and dicircumcoronene C 95 H 24 (LIV) as the graphite (0001) monovacancy defect model. We found that the adsorption reactions of O and O 2 on the L0D surface can produce defects on the graphite surface. O can yield CO, while O 2 can yield both CO and CO 2 molecules. The adsorption reactions of the O and O 2 on the LIV surface can produce a 2-C defective graphite surface and CO, and CO and CO 2 , respectively. The O and O 2 more readily oxidize the defected surface, LIV, than the defect-free surface, L0D. On the basis of the computed reaction pathways, we predict reaction rate constants in the temperature range between 300 and 3000 K using RiceÀRamspergerÀKasselÀMarcus (RRKM) theory. High-temperature quantum chemical molecular dynamics simulations at 3000 K based on on-the-fly DFTB-D energies and gradients support the results of our PES studies.

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“…Under these conditions, considerable reaction occurred at room temperature during the period of 1 h. Presumably considerable surface heating took place as a result of deactivation of excited species. 15 The etch patterns produced on the graphite by oxidation with atomic oxygen, the plasma surrounding the graphite, were quite different from those produced in the absence of the plasma. At 200"C, reaction for 1 h produced pits of diameter of lO,OOOA, much larger than those produced in the absence of plasma.…”

Section: Electron Microscopymentioning

confidence: 96%

Oxidation of carbons and graphites by atomic oxygen an electron microscope study of surface changes

Marsh¹,

O'Hair²,

Reed³

1965

Trans. Faraday Soc.

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Crystalline Ticonderoga graphite, a pyrolytic graphite and two amorphous carbons have been oxidized with atomic oxygen and those changes which occur on the surfaces have been examined by optical and electron microscopy. Such a study assists in the understanding of the nature of " active sites " on carbonaceous surfaces. Unlike the reaction with molecular oxygen, atomic oxygen produced a general background of conical pits on surfaces of crystalline graphite, but not on the pyrolytic graphite, as well as what are considered to be etch pits, associated with defect structures. There was much less structural reaction anisotropy during oxidation by atomic oxygen than by molecular oxygen. The presence of iron on the surface of Ticonderoga graphite promoted recombination of atomic oxygen, so decreasing oxidation rates and caused the formation of hexagonal hillocks. The edges of these hillocks are composed of (IOiO} or zig-zag planes. There is evidence to suggest the presence of pure defect centres on Ticonderoga graphite. Amorphous carbons appear to possess centres of preferential reactivity in that extensive pitting of the surface occurred.

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Reaction Kinetics of the Atomic Oxygen-Graphite System

Cited by 11 publications

References 6 publications

Oxidation of carbons and graphites by atomic oxygen kinetic studies

Oxidation of carbons and graphites by atomic oxygen kinetic studies

Quantum Chemical Prediction of Reaction Pathways and Rate Constants for the Reactions of O_x (x = 1 and 2) with Pristine and Defective Graphite (0001) Surfaces

Oxidation of carbons and graphites by atomic oxygen an electron microscope study of surface changes

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Reaction Kinetics of the Atomic Oxygen-Graphite System

Cited by 11 publications

References 6 publications

Oxidation of carbons and graphites by atomic oxygen kinetic studies

Oxidation of carbons and graphites by atomic oxygen kinetic studies

Quantum Chemical Prediction of Reaction Pathways and Rate Constants for the Reactions of Ox (x = 1 and 2) with Pristine and Defective Graphite (0001) Surfaces

Oxidation of carbons and graphites by atomic oxygen an electron microscope study of surface changes

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Quantum Chemical Prediction of Reaction Pathways and Rate Constants for the Reactions of O_x (x = 1 and 2) with Pristine and Defective Graphite (0001) Surfaces