Deterministic Covalent Organic Functionalization of Monolayer Graphene with 1,3-Dipolar Cycloaddition Via High Resolution Surface Engineering

TL;DR

This paper demonstrates a precise, reversible method for spatially-controlled organic functionalization of monolayer graphene using electron beam-induced defect engineering and 1,3-dipolar cycloaddition, enabling nanoscale device fabrication.

Contribution

It introduces a novel technique combining electron beam irradiation with cycloaddition for spatially-resolved, reversible graphene functionalization at the nanoscale.

Findings

Successful spatial patterning of graphene reactivity via electron beam defects

Confirmation of selective functionalization through microscopy and spectroscopy

Reversible functionalization demonstrated by laser-induced desorption

Abstract

Spatially-resolved organic functionalization of monolayer graphene is successfully achieved by combining low-energy electron beam irradiation with 1,3-dipolar cycloaddition of azomethine ylide. Indeed, the modification of the graphene honeycomb lattice obtained via electron beam irradiation yields to a local increase of the graphene chemical reactivity. As a consequence, thanks to the high-spatially resolved generation of structural defects (~ 100 nm), chemical reactivity patterning has been designed over the graphene surface in a well-controlled way. Atomic force microscopy and Raman spectroscopy allow to investigate the two-dimensional spatial distribution of the structural defects and the new features that arise from the 1,3-dipolar cycloaddition, confirming the spatial selectivity of the graphene functionalization achieved via defect engineering. The Raman signature of the functionalized graphene is investigated both experimentally and via ab initio molecular dynamics simulations, computing the power spectrum. Furthermore, the organic functionalization is shown to be reversible thanks to the desorption of the azomethine ylide induced by focused laser irradiation. The selective and reversible functionalization of high quality graphene using 1,3-dipolar cycloaddition is a significant step towards the controlled synthesis of graphene-based complex structures and devices at the nanoscale.