Graphene-Based Materials and Their Functionalization Applications

Graphene, a single layer of sp²-bonded carbon atoms arranged in a two-dimensional honeycomb lattice, has been celebrated for its exceptional electrical conductivity, mechanical strength and large specific surface area. However, pristine graphene’s hydrophobicity and chemical inertness can limit its direct integration into diverse applications. Graphene oxide (GO), produced by the controlled oxidation of graphite, introduces oxygen-containing groups that render the sheets dispersible in polar solvents and amenable to chemical modification. Reduction of GO to reduced graphene oxide (rGO) partially restores the conjugated network while retaining surface defects that serve as anchor points for further functionalisation. Functionalisation strategies broadly encompass covalent approaches, whereby chemical bonds are formed between surface carbons and grafted moieties, and non-covalent methods, which exploit π–π stacking, van der Waals forces or electrostatic interactions. Such tailored surface engineering enables the assembly of hybrid nanocomposites, the tuning of electronic band structures and the incorporation of graphene into polymer matrices, biosensors, energy storage devices and catalytic platforms. Recent advances have focused on precise control of functional group density, the development of stimuli-responsive coatings and the formation of hierarchical architectures, all of which enhance performance in areas as diverse as solar energy conversion, environmental remediation and biomedical diagnostics.

Research from Nature Portfolio

Researchers have developed an aminated graphene derivative by simultaneous reduction and amination of GO under mild liquid-phase conditions, yielding rGO sheets bearing amine functionalities at approximately 4 at. %. These amine groups enable covalent coupling with a range of organic molecules and polymers, enhancing electrical conductivity, lowering work function and inducing controllable wrinkling of the graphene layers. The resulting material shows promise for photovoltaic, biosensing and catalytic applications, as well as serving as a versatile precursor for further chemical modifications.

A novel Raman spectroscopic metric has been introduced for the characterisation of GO and its derivatives, addressing longstanding ambiguities in the interpretation of defect-related peaks. By recognising that the traditional G peak is a superposition of true G and D′ bands, the new method incorporates the overtone D′ (2D′) peak and refines estimates of oxygen content and defect density. This advance allows more reliable monitoring of reduction processes and optimisation of purification techniques, defining distinct regimes of structural evolution that correlate with conductivity gains.

Research from all publishers

A comprehensive review of functional modification strategies for graphene and GO highlights covalent binding, non-covalent assembly and elemental doping as principal routes to tailor interfacial properties. The survey emphasises how each method influences electronic, optical and mechanical characteristics, and it maps these effects onto prospective applications in composites, sensors and energy devices. Key challenges, such as scalable production of uniformly functionalised sheets and control over defect distribution, are identified alongside future research directions.

Laser scribing has emerged as a rapid and versatile technique for the reduction of GO films, with parameters such as scan speed, number of passes and material coverage critically affecting the degree of restoration of sp² domains. Systematic Raman analysis demonstrates that slower scan speeds can lead to incomplete reduction, while multiple passes yield marked improvements. This approach offers a mask-free route to pattern conductive graphene features on flexible substrates for electronic and sensing applications.

Investigations into the chemical composition of GO and its impact on Raman spectra have clarified the role of defect types and distributions in shaping spectral bands. By correlating variations in oxygen functional groups with peak positions, intensities and widths, researchers have provided a more unified framework for interpreting spectroscopic data. This understanding aids in tracking structural changes during thermal annealing and in the design of heterogeneous GO-based heterostructures.

Graphene-Based Materials and Their Functionalization Applications publication trend

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

Technical terms

Graphene oxide (GO): A layered carbon material bearing oxygenated functional groups (hydroxyl, epoxide, carboxyl) that confer hydrophilicity and chemical reactivity.

Reduced graphene oxide (rGO): GO that has undergone chemical, thermal or photonic reduction to partially restore the sp² carbon network while retaining defects and residual oxygen functionalities.

Covalent functionalisation: Chemical modification involving the formation of strong covalent bonds between graphene surface atoms and grafted functional groups or polymers.

Non-covalent functionalisation: Surface modification achieved through π–π stacking, van der Waals interactions or electrostatic forces without altering the graphene backbone.

Polymer nanocomposite: A composite material in which functionalised graphene sheets are uniformly dispersed within a polymer matrix to enhance mechanical, electrical or thermal properties.

References

1. Progress in the functional modification of graphene/graphene oxide: a review. RSC Advances (2020).
2. A New Raman Metric for the Characterisation of Graphene oxide and its Derivatives. Scientific Reports (2016).
3. From graphene oxide towards aminated graphene: facile synthesis, its structure and electronic properties. Scientific Reports (2020).
4. Raman Spectroscopy Investigation of Graphene Oxide Reduction by Laser Scribing. C – Journal of Carbon Research (2021).
5. Towards Understanding the Raman Spectrum of Graphene Oxide: The Effect of the Chemical Composition. Coatings (2020).