Stabilizing Edge Fluorination in Graphene Nanoribbons

ACS Nano - 2020    
Mirco Panighel, Sabela Quiroga, Pedro Brandimarte, Cesar Moreno, Aran Garcia-Lekue, Manuel Vilas-Varela, Dulce Rey, Guillaume Sauthier, Gustavo Ceballos, Diego Peña, and Aitor Mugarza
Abstract

The on-surface synthesis of edge-functionalized graphene nanoribbons (GNRs) is challenged by the stability of the functional groups throughout the thermal reaction steps of the synthetic pathway. Edge fluorination is a particularly critical case in which the interaction with the catalytic substrate and intermediate products can induce the complete cleavage of the otherwise strong C-F bonds before the formation of the GNR. Here, we demonstrate how a rational design of the precursor can stabilize the functional group, enabling the synthesis of edge-fluorinated GNRs. The survival of the functionalization is demonstrated by tracking the structural and chemical transformations occurring at each reaction step with complementary X-ray photoelectron spectroscopy and scanning tunneling microscopy measurements. In contrast to previous attempts, we find that the C-F bond survives the cyclodehydrogenation of the intermediate polymers, leaving a thermal window where GNRs withhold more than 80% of the fluorine atoms. We attribute this enhanced stability of the C-F bond to the particular structure of our precursor, which prevents the cleavage of the C-F bond by avoiding interaction with the residual hydrogen originated in the cyclodehydrogenation. This structural protection of the linking bond could be implemented in the synthesis of other sp2-functionalized GNRs.

Press release

Our paper was highlighted at ICN2 NEWS - November 26th, 2020.

Bibtex citation
@Article{Panighel2020,
  author    = {Mirco Panighel and Sabela Quiroga and Pedro Brandimarte and Cesar Moreno and Aran Garcia-Lekue and Manuel Vilas-Varela and Dulce Rey and Guillaume Sauthier and Gustavo Ceballos and Diego Pe{\~{n}}a and Aitor Mugarza},
  title     = {Stabilizing Edge Fluorination in Graphene Nanoribbons},
  journal   = {ACS Nano},
  year      = {2020},
  volume    = {14},
  number    = {9},
  pages     = {11120--11129},
  issn      = {1936--0851},
  doi       = {10.1021/acsnano.0c01837},
  publisher = {American Chemical Society ({ACS})},
}
Key words
  • graphene nanoribbons
  • chemical functionalization
  • edge topology
  • on-surface synthesis
  • scanning tunnelling microscopy
  • density functional theory
  • self-assembly
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Physical Review Letters - 2020