Issue 5, 2021

Incorporation-limiting mechanisms during nitrogenation of monolayer graphene films in nitrogen flowing afterglows

Abstract

Monolayer graphene films are exposed to the flowing afterglow of a low-pressure microwave nitrogen plasma, characterized by the absence of ion irradiation and significant populations of N atoms and N2(A) metastables. Hyperspectral Raman imaging of graphene domains reveals damage generation with a progressive rise of the D/G and D/2D band ratios following subsequent plasma treatments. Plasma-induced damage is mostly zero-dimensional and the graphene state remains in the pre-amorphous regime. Over the range of experimental conditions investigated, damage formation increases with the fluence of energy provided by heterogenous surface recombination of N atoms and deexcitation of N2(A) metastable species. In such conditions, X-ray photoelectron spectroscopy reveals that the nitrogen incorporation (either as pyridine, pyrrole, or quaternary moieties) does not simply increase with the fluence of plasma-generated N atoms but is also linked to the damage generation. Based on these findings, a surface reaction model for monolayer graphene nitrogenation is proposed. It is shown that the nitrogen incorporation is first limited by the plasma-induced formation of defect sites at low damage and then by the adsorption of nitrogen atoms at high damage.

Graphical abstract: Incorporation-limiting mechanisms during nitrogenation of monolayer graphene films in nitrogen flowing afterglows

Supplementary files

Article information

Article type
Paper
Submitted
02 Nov 2020
Accepted
25 Jan 2021
First published
28 Jan 2021

Nanoscale, 2021,13, 2891-2901

Incorporation-limiting mechanisms during nitrogenation of monolayer graphene films in nitrogen flowing afterglows

G. Robert Bigras, R. Martel and L. Stafford, Nanoscale, 2021, 13, 2891 DOI: 10.1039/D0NR07827A

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