Covalent Functionalization of Graphene Materials

Graphene’s exceptional electrical, mechanical and thermal characteristics derive from its two-dimensional sp2-hybridised carbon lattice. Yet, its intrinsic chemical inertness and zero band gap limit its direct deployment in many applications. Covalent functionalization addresses these constraints by forming strong chemical bonds between graphene’s basal plane or edge carbon atoms and external moieties. Such tailored modifications can open and tune a band gap, enhance solubility, direct self-assembly and introduce specific reactivity for sensing or catalysis. Strategies include radical-mediated grafting, cycloaddition reactions and defect-activated chemistries. By choosing appropriate reagents—ranging from aryl diazonium salts to carbene or nitrene precursors—researchers can precisely control the degree and pattern of functionalisation. The result is a versatile platform in which graphene’s core π-conjugation is judiciously perturbed to meet requirements in electronics, photovoltaics, sensing, energy storage and biomedicine, while retaining sufficient conductivity and mechanical integrity.

Research from Nature Portfolio

Recent studies have demonstrated heat-initiated radical chemistries that uniformly graft functional groups across wafer-scale graphene under oxygen-free conditions, enabling scalable covalent modification of both basal planes and edges. Investigations into atomic vacancies have revealed that carbon dangling bonds serve as active sites for highly selective attachment of amino-terminated molecules, achieving functionalisation without degrading the π-network or electronic performance. More recently, spatially resolved covalent patterning—termed molecular embroidery—has been realised by iterative electron-beam lithography, reduction and covalent binding cycles. This approach yields concentric domains of distinct chemical addends on a single flake, offering a blueprint for programmable nanoarchitectures and multifunctional device interfaces.

Covalent Functionalization of Graphene Materials publication trend

The graph below shows the total number of articles in covalent functionalization of graphene materials across all publications each year (not limited to Nature Index journals).

Technical terms

Covalent functionalization: Formation of robust chemical bonds between graphene’s carbon atoms and external functional groups to alter its properties.

Basal plane: The primary two-dimensional surface of graphene composed of a hexagonal network of carbon atoms.

Radical reaction: A chemical pathway involving species with unpaired electrons that initiate covalent bond formation.

Lithographic patterning: Use of electron-beam or photolithography to define regions for selective chemical modification.

π-conjugated network: The continuous system of overlapping p-orbitals in graphene responsible for its unique electronic characteristics.

References

1. Graphene: Preparation, tailoring, and modification. Exploration (2023).
2. Heat-Initiated Chemical Functionalization of Graphene. Scientific Reports (2016).
3. Highly selective covalent organic functionalization of epitaxial graphene. Nature Communications (2017).
4. Molecular embroidering of graphene. Nature Communications (2021).
5. Pristine graphene covalent functionalization with aromatic aziridines and their application in the sensing of volatile amines – an ab initio investigation. RSC Advances (2021).
6. Highly Efficient and Reversible Covalent Patterning of Graphene: 2D‐Management of Chemical Information. Angewandte Chemie International Edition (2020).