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Covalent Functionalization by Cycloaddition Reactions of Pristine Defect-Free Graphene
Lakshya Daukiya1, Cristina Mattioli2, Dominique Aubel1
1Institut de Sciences des Matériaux de Mulhouse, CNRS-UMR 7361, Université de Haute Alsace , 3Bis, rue Alfred Werner, Mulhouse 68093, France.
ACS Nano
|December 28, 2016
Summary
This study visualizes cycloaddition reactions on defect-free graphene at room temperature, challenging previous assumptions. Fluorinated maleimide molecules covalently bond, altering graphene
Area of Science:
- Materials Science
- Surface Chemistry
- Condensed Matter Physics
Background:
- Cycloaddition reactions on graphene were previously thought to require defects.
- Understanding molecular grafting on graphene is crucial for electronic applications.
Purpose of the Study:
- To directly visualize cycloaddition reactions of fluorinated maleimides on graphene.
- To investigate the possibility of such reactions on defect-free graphene at room temperature.
- To characterize the resulting molecular and electronic changes in graphene.
Main Methods:
- Low-temperature scanning tunneling microscopy (LT-STM) for direct visualization.
- Density Functional Theory (DFT) calculations to determine reaction pathways.
- T-matrix approximation calculations for analyzing reaction anisotropy.
- X-ray Photoelectron Spectroscopy (XPS) and Angle-Resolved Photoemission Spectroscopy (ARPES) for elemental and electronic analysis.
Main Results:
- Direct visualization of cycloaddition reaction between fluorinated maleimides and defect-free graphene at room temperature.
- Observation of covalent grafting, breaking sp2 conjugation and forming sp3 bonds in graphene.
- Anisotropic standing-wave patterns attributed to (1,2) cycloaddition.
- DFT calculations confirmed (1,2) cycloaddition preference on graphene/SiC(0001).
- XPS and ARPES revealed an electronic band gap opening in graphene.
Conclusions:
- Cycloaddition reactions can occur on defect-free graphene at room temperature.
- Molecular grafting modifies graphene's electronic structure, creating a band gap.
- The findings open new avenues for graphene functionalization and electronic device design.
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