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Title: Nitrogen Doping Enables Covalent-Like π–π Bonding between Graphenes

In neighboring layers of bilayer (and few-layer) graphenes, both AA and AB stacking motifs are known to be separated at a distance corresponding to van der Waals (vdW) interactions. In this Letter, we present for the first time a new aspect of graphene chemistry in terms of a special chemical bonding between the giant graphene "molecules". Through rigorous theoretical calculations, we demonstrate that the N-doped graphenes (NGPs) with various doping levels can form an unusual two-dimensional (2D) pi-pi bonding in bilayer NGPs bringing the neighboring NGPs to significantly reduced interlayer separations. The interlayer binding energies can be enhanced by up to 50% compared to the pristine graphene bilayers that are characterized by only vdW interactions. Such an unusual chemical bonding arises from the pi-pi overlap across the vdW gap while the individual layers maintain their in-plane pi-conjugation and are accordingly planar. Moreover, the existence of the resulting interlayer covalent-like bonding is corroborated by electronic structure calculations and crystal orbital overlap population (COOP) analyses. In NGP-based graphite with the optimal doping level, the NGP layers are uniformly stacked and the 3D bulk exhibits metallic characteristics both in the in-plane and along the stacking directions.
Authors:
 [1] ;  [2] ;  [1] ;  [2] ;  [2] ;  [3]
  1. Sichuan Univ., Chengdu (China)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. Georgetown Univ., Washington, DC (United States)
Publication Date:
OSTI Identifier:
1261464
Grant/Contract Number:
AC05-00OR22725; 21443012; CHE-1006702; AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Nano Letters
Additional Journal Information:
Journal Volume: 15; Journal Issue: 8; Journal ID: ISSN 1530-6984
Publisher:
American Chemical Society
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
Sponsoring Org:
USDOE Office of Science (SC); National Science Foundation of China; National Science Foundation (NSF)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE graphene; nitrogen doping; interlayer separation; pi-pi bonding; pancake bonding; van der Waals; CHEMICAL-VAPOR-DEPOSITION; N-DOPED GRAPHENE; BILAYER GRAPHENE; ELECTRONIC-STRUCTURE; MONOLAYER GRAPHENE; BORON; GRAPHITE; CRYSTAL; PANCAKE; DIMERS