Atomic Oxygen Chemisorption on Carbon Nanotubes Revisited with Theory and Experiment

Kroes, Jaap; Pietrucci, Fabio; Curioni, A.; Jaafar, Rached; Gröning, Oliver; Andreoni, Wanda

doi:10.1021/jp310332y

Cited by 8 publications

(16 citation statements)

References 35 publications

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“…On (12,0) carbon nanotubes, ether-like structures are predicted for the oxygen adsorption on both a defect-free surface and a defective surface in the presence of an SW defect (Figure 1g,h). Consistent with the previous work on (10,0) defect-free nanotubes, 60 O adsorption on the bridge site of an axis C−C bond with the formation of an epoxide is more endothermic by 0.15 eV as compared to that on a zigzag C−C bond, where ether formation is favored. The presence of an SW defect lowers the adsorption energy by 0.7 eV (Figure 1h).…”

Section: ■ Computational Methodssupporting

confidence: 89%

Nature of Oxygen Adsorption on Defective Carbonaceous Materials

Fang

Dixon

et al. 2021

J. Phys. Chem. C

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Plane-wave density functional theory has been used to study oxygen adsorption on graphene, graphite, and (12,0) zigzag single-walled carbon nanotubes with and without Stone–Wales (SW) and single-vacancy (SV) defects to understand the role of defects on carbonaceous material reactivity. Atomic oxygen adsorption leads to the formation of an epoxide on defect-free graphene and graphite and an ether on the exterior wall of carbon nanotubes and SW-defected materials. O2 chemisorption is endothermic on defect-free graphene and graphite and slightly exothermic on defect-free nanotubes. O2 chemisorption energies are predicted to be −1.1 to −1.4 eV on an SW defect and −6.0 to −8.0 eV on an SV defect. An SW defect lowers the energy barriers by 0.90 and 0.50 eV for O2 chemisorption on graphene and nanotubes, respectively. The formation of a C–O–O–C group is important for O2 dissociation on defect-free and SW-defected materials. The energy barrier is less than 0.30 eV on an SV defect. The more reactive SW defect toward O adsorption on graphene is mostly due to the strained defective carbon atoms being able to donate more electrons to an O to form an ether. The larger 2s character in the hybrid orbitals in an ether than in an epoxide makes the ether C–O bond stronger. Stronger C–O binding on an SW-defective carbon nanotube than on a defect-free nanotube is in part due to more flexibility of the defect to release the epoxide ring strain to form an ether.

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Section: ■ Computational Methodssupporting

confidence: 89%

Nature of Oxygen Adsorption on Defective Carbonaceous Materials

Fang

Dixon

et al. 2021

J. Phys. Chem. C

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“…The solution should come from ab initio calculations. Only recently, however, we have shown that at very low coverage atomic oxygen highly prefers ether configurations on the sidewall of a SWNT of ∼1 nm diameter and that using atomistic models of small sizes severely affects the ET-EP energy differences . Moreover, with a joint computational (DFT-based) and experimental (scanning-tunneling spectroscopy (STS)) approach, we showed that metastable epoxides can act as effective kinetic traps for oxygen and give rise to characteristic impurity levels in the gap of the nanotube.…”

Section: Introductionmentioning

confidence: 99%

“…However, the success of the reactive force-field ReaxFF in the simulation of carbon nanotube growth, and also graphene oxide, suggests that a careful analysis of its performance for oxygen adsorbates on CNTs could be useful at this stage. Following our first encouraging findings, here, we apply the ReaxFF potential to the same problems mentioned above, thus obtaining a detailed comparison with the DFT-PBE results.…”

Section: Introductionmentioning

confidence: 99%

Characterizing and Understanding Divalent Adsorbates on Carbon Nanotubes with Ab Initio and Classical Approaches: Size, Chirality, and Coverage Effects

Kroes

Pietrucci

Curioni

et al. 2014

J. Chem. Theory Comput.

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The study of oxygen chemisorption on single-walled carbon nanotubes generally relies on simple atomistic models and hence hampers the possibility to understand whether nanotube size or adduct concentration have a role in determining the surface-adsorbate interaction. Our large-scale DFT-based simulations show that structural and electronic properties as well as diffusion barriers strongly depend on both nanotube diameter and adsorbate concentration. Our atomistic models cover nanotube of different chirality with diameters from 0.6 to 1.5 nm and oxygen concentration from 0.1 to 1%. In particular, the tendency to cluster increases with concentration and stabilizes ether (ET) groups but affects hopping barriers only to a minor extent. Significant differences with graphene are found, also for 1.5 nm diameter nanotubes. Extension to species isoelectronic to oxygen reveals dissimilarities, and especially for sulfur that tends to form epoxides (EP), to diffuse more easily and to rapidly close the energy gap for increasing concentration. The relative ET-EP stability can be described in terms of the bare-bond curvature, a concentration-dependent chemical descriptor here introduced. Comparison of these DFT calculations-using different exchange-correlation functionals-and our additional investigation with a reactive force-field (ReaxFF) clarifies several similarities but also discrepancies between the predictions of the two schemes.

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“…1,46 More generally, other studies have shown that chirality is expected to have a direct effect on oxygen sidewall chemisorption and can affect chemical reactivity in general. 47,48 Depending on the etching gas and the particular treatment, there are already some reports indicating that m-CNTs may etch more rapidly with gas-phase oxidants than s-CNTs. 2,36À38,40,49 Using laser irradiation in air, Huang et al observed both the preferential destruction of m-CNTs and high chiral angle s-CNTs.…”

mentioning

confidence: 99%

“…These purely geometric arguments predict faster etch rates for small-diameter nanotubes and do not in themselves explain differences in electronic type, e.g ., differing etch rates for metallic CNTs (m-CNTs) and semiconducting CNTs (s-CNTs). Doping, however, is expected to be as significant a factor as chiral angle. , More generally, other studies have shown that chirality is expected to have a direct effect on oxygen sidewall chemisorption and can affect chemical reactivity in general. , …”

mentioning

confidence: 99%

Type- and Species-Selective Air Etching of Single-Walled Carbon Nanotubes Tracked with in Situ Raman Spectroscopy

2013

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The thermal oxidation of carbon nanotubes in air is investigated by in situ Raman spectroscopy. Etching rates are directly seen to be diameter, chirality, and type dependent. We directly track the evolution of bundled nanotube networks that undergo air etching from 300 to 600 °C. Some species are more robust than others. Changes to radial breathing mode (RBM) and G– peak structures suggest that metallic species etch away more rapidly, with smaller diameter semiconducting species etching more slowly and large diameter nanotubes, including semiconductors, etching last. The decay in integrated G and D band intensities is tracked and fit reasonably well with biexponential decay. The RBM evolution is better represented by a single exponential. All bands are fit to activation plots with RBMs showing significantly different rates.

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Atomic Oxygen Chemisorption on Carbon Nanotubes Revisited with Theory and Experiment

Cited by 8 publications

References 35 publications

Nature of Oxygen Adsorption on Defective Carbonaceous Materials

Nature of Oxygen Adsorption on Defective Carbonaceous Materials

Characterizing and Understanding Divalent Adsorbates on Carbon Nanotubes with Ab Initio and Classical Approaches: Size, Chirality, and Coverage Effects

Type- and Species-Selective Air Etching of Single-Walled Carbon Nanotubes Tracked with in Situ Raman Spectroscopy

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