Physicochemical Properties of Graphene Oxide in Aqueous Systems

Graphene oxide (GO) comprises single to few-layer sheets of oxidised graphene bearing hydroxyl, epoxy and carboxyl groups. In water, these oxygen functionalities confer hydrophilicity, surface charge and the ability to engage in hydrogen bonding, electrostatic interactions and π–π stacking. The balance between these forces governs colloidal stability, aggregation and dispersion. Key parameters such as pH, ionic strength and the nature of co- and counter-ions modulate the electrostatic repulsion of deprotonated groups and drive the assembly of GO into extended flakes, stacked aggregates or stable dispersions. Under illumination, GO undergoes photochemical transformations: initial photoreduction removes oxygen moieties to form porous reduced GO, while further radical-mediated oxidation fragments sheets into smaller entities. Advanced spectroscopy, theoretical calculations and coarse-grained simulations have elucidated the ultrafast dynamics of these processes and the interplay between surface chemistry and solution conditions. Mastery of these physicochemical properties underpins applications in environmental remediation, sensing, composite materials and the assessment of GO’s environmental fate.

Research from Nature Portfolio

Picosecond transient absorption experiments have resolved the fundamental mechanism of ultraviolet-induced photoreduction in aqueous GO, demonstrating that solvated electrons generated by femtosecond pulses initiate a chain reaction of oxygen-group removal within picoseconds. This insight enables the design of GO systems with controlled photostability. Batch studies combined with spectroscopy and density-functional theory have characterised GO coagulation onto titanium dioxide, showing that neutral pH and multivalent cations compress the electrical double layer to accelerate removal, whereas anions and hydrogen bonds can stabilise dispersions. Large-scale coarse-grained molecular dynamics simulations have mapped GO morphologies as functions of oxidation degree, pH and cation type: acidic conditions and low oxidation yield stacked aggregates via hydrogen bonding, while high pH promotes dispersion despite intermittent face-edge aggregation; calcium ions further enhance face-face clustering through bridging interactions.

Physicochemical Properties of Graphene Oxide in Aqueous Systems publication trend

The graph below shows the total number of articles in physicochemical properties of graphene oxide in aqueous systems across all publications each year (not limited to Nature Index journals).

Technical terms

Graphene oxide (GO): Single to few-layer sheets of oxidised graphene bearing hydroxyl, epoxy and carboxyl groups that confer hydrophilicity and surface charge.

Photoreduction: Light-initiated removal of oxygen functionalities from GO, altering its structure and electronic properties.

Zeta potential: Electrokinetic potential at the slipping plane of colloidal particles, indicative of dispersion stability.

π–π interactions: Non-covalent stacking forces between aromatic graphitic domains in GO sheets.

Critical coagulation concentration (CCC): Minimum ionic concentration required to overcome electrostatic repulsion and induce rapid particle aggregation.

References

1. Revealing the ultrafast process behind the photoreduction of graphene oxide. Nature Communications (2013).
2. Complex Roles of Solution Chemistry on Graphene Oxide Coagulation onto Titanium Dioxide: Batch Experiments, Spectroscopy Analysis and Theoretical Calculation. Scientific Reports (2017).
3. Principles governing control of aggregation and dispersion of aqueous graphene oxide. Scientific Reports (2021).
4. Toward a New Understanding of Graphene Oxide Photolysis: The Role of Photoreduction in Degradation Pathway. Advanced Science (2025).
5. Applications of graphene oxide (GO) in oily wastewater treatment: Recent developments, challenges, and opportunities. Journal of Environmental Management (2024).