Nature of Oxygen Adsorption on Defective Carbonaceous Materials

Zongtang Fang, Lan Li, David A. Dixon, Rebecca R. Fushimi, Eric J. Dufek

Research output: Contribution to journalArticlepeer-review

Abstract

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. O 2 chemisorption is endothermic on defect-free graphene and graphite and slightly exothermic on defect-free nanotubes. O 2 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 O 2 chemisorption on graphene and nanotubes, respectively. The formation of a C–O–O–C group is important for O 2 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.

Original languageAmerican English
JournalMaterials Science and Engineering Faculty Publications and Presentations
StatePublished - 23 Sep 2021

Keywords

  • adsorption
  • carbon nanotubes
  • ethers
  • oxygen
  • two dimensional materials

EGS Disciplines

  • Materials Science and Engineering

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